Precast plastic permanent stair treads and landing / platform planks

Abstract

A permanent stair tread for installation in a building stairway structure, the stairway structure including the permanent stair tread can attach to and be supported by a stringer or a pair of opposed stringers. The permanent stair tread has a core structure, the core structure composed of inorganic materials in the range of greater than ninety four percent and up to and including one hundred percent.

Description

PRECAST PLASTIC PERMANENT STAIR TREADS ANDLANDING / PLATFORM PLANKSTECHNICAL FIELD

[0001] This invention claims priority to provisional patent application Ser. No. 63 / 523,989, filed June 29, 2023, to the extent allowed by law.

[0002] The present invention pertains generally to permanent lightweight but sturdy structurally rated and fire rated stair treads and landing / platform plank products and assemblies for buildings. More specifically, the present invention comprises various embodiments of precast plastic permanent stair treads, risers, and landing / platform plank, and assemblies of same, that are installed in metal or wood framed stairway structures, decks, balconies, platforms or walkways, including structural support elements, either during initial construction of the building or during renovation, improvements or repair phases for both interior and exterior building stairway structures.BACKGROUND

[0003] Description of the Prior Art.

[0004] During the construction of a commercial, residential, medical, educational, etc. building, stairway frameworks of a myriad of designs, styles and materials are at some point installed. The stair structure, including stair treads and landing / platform frameworks are used byconstruction workers to access and egress the building during construction, and are also used by the users of the building after construction is completed.

[0005] The typical walking structure framework has previously used concrete, metal or wood finishes which were permanently and directly installed to the stair stringers or substructure frameworks with or without additional support elements. Some sub-structure frameworks use 3-sided or 4-sided “concrete filled” stair pans into which wet concrete is poured before curing. The tread or landing / platform portions of the frameworks are installed as construction, remodeling, renovations or repairs as the building advances.

[0006] Present construction processes use concrete or an equivalent rather heavy material, such as either pre-cast concrete, metal, or a wood member, attached as a free span or onto a sub frame support, or concrete poured into the stair pan or landing / platform pan already installed in the framework, to form the permanent walking surface for stair treads, landings / platforms, balconies or walkways of the stairway structure. A typical pre-cast concrete tread, wood tread or concrete filled stair pan structure of a stairway framework may include a bullnose feature at the front end of the stair tread. Concrete filled stair pans include an upper lip extending rearwardly a short distance of between one half to one and one half inches typically towards the riser portion of the metal stairway framework located at the rear of each stair pan. The bullnose structure is a requirement of most, if not all, building codes. The radius of the bullnose may differ from one stairway framework manufacturer to another, or between architects. In addition, the thickness of the metal comprising the stair pan and the bullnose feature may vary from manufacturer to manufacturer. The horizontal length and / or width of the tread portion of the stairway may also vary from building to building.

[0007] Regulatory standards require that all finished stair treads and nosings be made ofand have a slip resistant surface. This requirement is satisfied by embodiments of the presently disclosed stair tread and landing / platform planks.

[0008] Depending on the use of the building, some regulatory standards require some or all stairs to include photoluminescent, abrasive, contrasting stripe stair treads and landing nosings. The presently disclosed stair tread and landing plank assemblies and configurations can include a surface adapted to include a photoluminescent, abrasive, and contrasting stripe nosing to meet the standards required by the International Building Code (TBC), International Fire Code (IFC), National Fire Protection Association (NFPA), Underwriter’s Limited (UL), American Society for Testing and Materials (ASTM) and other applicable codes.

[0009] Many currently available building materials utilized to severe as stair treads contain organic materials, such as wood for example. In use, such building materials are susceptible to the formation of mold and / or rot, and destruction by termites, ants, and other insects. Water absorption and chemical damage also results when organic and water soluble materials are used to manufacture these building materials.

[0010] The presently disclosed stair treads and landing planks consist only of inorganic materials that are insoluble to water, resistant to mold, rot and termite and insect infestation. The presently disclosed stair tread is also water and chemically resistant. The same is true when the same inorganic stair tread composition is used to fabricate landing and platform planks.

[0011] In an embodiment, the present precast plastic permanent stair treads and landing and platform planks are manufactured from a proprietary matrix of inorganic recycled and / or virgin high quality HDPE (high density polyethylene), LDPE (low density polyethylene) and glass fibers to prevent deterioration. The matrix of this or other embodiments also may include surface binders, foaming agents, UV inhibited additives, antioxidant processing aids, colorantadditives, and fire resistance additives.

[0012] U.S. Patent No. 9,169,650 discloses a stair tread having a metal core partially covered with high-strength concrete. The core, in an embodiment, has a pair of horizontally extending spaced apart metal plates, and a grid of vertically extending metal support walls between the two metal plates. An embodiment also includes retention elements extending upward from and across the top of the upper plate to secure the concrete to the core. This embodiment has one profile and cannot “free span” between opposed stingers.

[0013] The presently disclosed precast plastic permanent stair treads and landing planks, and related stairway assemblies, have the structural ability to free span between opposed stingers, can be adapted to have multiple styles of non-skid surface designs, multiple sized and shaped profiles, and incorporate and work with multiple nosing designs. In addition, the presently disclosed stair treads and landing planks are impervious to weather and are UV resistant, chemically resistant and can be made in any color. Their light weight enables easy construction, easy logistics, and easy installation.

[0014] U.S. Patent Nos. 10,570,623 and 10,676,939 each relate to a temporary stair tread insert and method of installation. The temporary tread can be made from any one of several plastic materials. However, these patents do not describe a permanent precast recyclable structurally and fire rated stair tread.

[0015] Users of the temporary stair treads disclosed in U.S. Patent Nos 10,570,623 and 10,676,939 inquired of applicant whether a similar permanent stair tread could be fabricated to replace permanent concrete and steel stair treads. Applicant's determined that the temporary stair treads disclosed in the '623 and '939 patents could not be used as permanent stair treads due to the fact that the front nose of the '623 and '939 stair treads stuck out which caused trippinghazards and violated the existing building code requirements. Applicant obtained samples of a new precast plastic material from which permanent stair treads of various shapes, designs and composition could be fabricated.SUMMARY OF THE INVENTION

[0016] The present invention comprises precast permanent stair treads, risers and landing planks and platform planks for use in stairways of buildings. The stair treads or landing planks, in an embodiment are fabricated from inorganic materials, including recycled pre-consumer, post-consumer and / or virgin high density polyethylene (HDPE), recycled pre-consumer, postconsumer and / or virgin low density polyethylene (LDPE), recycled pre-consumer, postconsumer and / or virgin fibrous glass materials, surface binders, foaming agents, UV inhibited additives, antioxidant processing aids, colorant additives and / or dye agents, and fire resistance additives.

[0017] Several methods of manufacture can be used to fabricate the stair tread, landing plank and platform planks described above. These include a hybrid process of compression molding and injection molding together, injection molding or compression molding separately, extrusion molding (sometimes known as plastification extruding and continuous extruding), blow molding, thermoforming, utilizing mechanical fasteners or adhesives to join multiple parts to produce the final stair tread profile, or any combination of these processes, or any combination of these processes.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Fig. l is a perspective view of an embodiment of a metal building stairway framework or stairway skeleton showing the front end of the laterally extending stair pans.Alternatively, the stairway framework or stairway skeleton could be of wood, installed on the bottom floor of a building under construction,;

[0019] Fig. 1 A is a perspective view of an embodiment of a single stringer stairway from underneath the stairway comprised of mixed materials.

[0020] Fig. 2 is a perspective profde view of a precast plastic permanent stair tread or landing plank according to one embodiment of the present invention;

[0021] Fig. 3 is an end view of an embodiment of the precast plastic permanent stair tread of Fig. 2;

[0022] Fig. 4 is a cross-section view of the stair tread embodiment of Fig. 3;

[0023] Fig. 5 is a cross sectional view of a stair tread embodiment having a partial foam core;

[0024] Fig. 6 is a cross sectional view of a precast plastic permanent stair tread embodiment comprising a solid core of two different colored plastic materials;

[0025] Fig. 7 is a cross sectional view of a precast plastic permanent stair tread embodiment reinforced with a plurality of glass fiber or metal rods;

[0026] Fig. 8 is a cross sectional view of a precast plastic permanent stair tread including anchor slots in the bottom of the stair tread adapted to accept attachment hardware;

[0027] Fig. 9 is a cross sectional view of a precast plastic permanent stair tread having laterally extending channels or grooves to accept adhesive on the bottom surface of the stair tread;

[0028] Fig. 10 is a cross sectional view of an embodiment of a precast plastic permanent stair tread including a plurality of slip resistant, non-skid or appearance texture grooves located on the upper surface of the stair tread;

[0029] Fig. 11 is a top plan view of a precast plastic permanent stair tread embodiment illustrating an additional array of non-skid grooves located on the upper surface of the stair tread;

[0030] Fig. 12 is a side elevation view of the embodiment of precast plastic permanent stair tread of Fig. 11;

[0031] Fig. 13 is a top plan view of another embodiment of the stair tread embodiment of Fig. 11, including a plurality of non-skid grooves located on a forward or leading portion of the supper surface;

[0032] Fig. 14 is a side elevation view of the embodiment of the precast plastic permanent stair of Fig. 13;

[0033] Fig. 15 is a top plan view of a precast plastic permanent stair tread embodiment accepting a surface mount abrasive, ribbed or photo luminescent metal or plastic nosing;

[0034] Fig. 16 is a side elevation view of the stair tread embodiment of Fig. 15;

[0035] Fig. 16A is a detail perspective view of the nosing of Figs. 15 and 16;

[0036] Fig. 17 is a top plan view of another embodiment of a precast plastic permanent stair tread having a forward groove accepting a flush mount abrasive, ribbed or photo luminescent metal or plastic nosing;

[0037] Fig. 18 is a side elevation view of the stair tread embodiment shown in Fig. 17;

[0038] Fig. 18A is a detail perspective view of the abrasive, ribbed or photo luminescent metal or plastic nosing of Figs. 17 and 18;

[0039] Fig. 19 is a top plan view of an embodiment of a precast plastic permanent stair tread with forwardly located non-skid grooves and a wider groove accepting an abrasive, ribbed or photo luminescent metal of plastic nosing;

[0040] Fig. 20 is a side elevation of the stair tread embodiment shown in Fig. 19;

[0041] Fig. 20A is a perspective detail view of the nosing of Figs. 19 and 20;

[0042] Fig. 21 is atop plan view of an embodiment of a precast plastic permanent stair tread having a cavity accepting an abrasive, ribbed or photo luminescent metal or plastic compression attachment nosing;

[0043] Fig. 22 is a side elevation view of the stair tread embodiment of Fig. 21;

[0044] Fig. 22A is a perspective detail view of the compression attachment nosing illustrated in Figs. 21 and 22;

[0045] Fig. 23 is a top plan view of a precast plastic permanent stair tread having a front groove adapted to accept a metal stair pan bull nose;

[0046] Fig. 24 is a front elevation view of the stair tread of Fig. 23;

[0047] Fig. 25 is a side elevation view of the stair tread embodiment of Figs. 23 and 24;

[0048] Fig. 26 is a side elevation view of a precast plastic permanent stair tread having opposed grooves for accepting a metal stair pan bull nose;

[0049] Fig. 27 is a top plan view of a precast plastic permanent stair tread having tapered sides and frontal groove profile configured to accept a metal bull nose stair pan as an alternative to pan fill concrete;

[0050] Fig. 28 is an end elevation view of the precast plastic permanent stair tread of Fig. 27;

[0051] Fig. 29 is a side elevation view of the precast plastic permanent stair tread of Figs. 27 and 28;

[0052] Fig. 30 is a cross-sectional view of a precast plastic permanent tongue and groove landing stair plank for planking stair landings and decks, the stair plank having a partial foam interior;

[0053] Fig. 31 is a cross-sectional view of two precast plastic permanent tongue and groove landing stair planks fitted together to provide planking for stair landings and decks;

[0054] Fig. 32 is a schematic view of two non-tongue and groove precast plastic permanent landing stair planks in fitting abutment for planking traditional decking and stair landings;

[0055] Fig. 33 is a cross-sectional view of a precast plastic permanent stair tread having a front edge angled taper;

[0056] Fig. 34 is a cross-sectional view of a precast plastic permanent stair tread having a front edge and a back edge angled taper;

[0057] Fig. 35 is a cross-sectional view of a precast plastic permanent stair tread assembly having a partial riser fastened at the front edge;

[0058] Fig. 36 is a cross-sectional view of a pre-cast plastic permanent stair tread assembly with a full riser attached to the front edge via an angled bracket;

[0059] Fig. 37 is a cross-sectional view of a precast plastic permanent stair tread assembly with a full riser fastened in a straight walled groove formed in the front portion of the stair tread;

[0060] Fig. 38 is a cross-sectional view of a precast plastic permanent stair tread assembly with a full riser held in a female keyhole formed in the tread;

[0061] Fig. 39 is a cross-sectional view of a precast plastic permanent stair tread where the front edge comprises an integral partial riser closure;

[0062] Fig. 40 is a cross-sectional view of a precast plastic permanent stair tread having an alternate profile design compared to the profile design of the stair tread of Fig. 39;

[0063] Fig. 41 is a cross-sectional view of an alternate profile of the precast plastic permanent stair tread illustrated in Fig. 39;

[0064] Fig. 42 is a cross-sectional view of a precast plastic permanent stair tread incorporating a full riser closure at the front end;

[0065] Fig. 43 is a cross sectional view of an alternate profde configuration of the stair tread of Fig. 42;

[0066] Fig. 44 is a schematic partial cross sectional view of a closed riser stairway assembly comprising metal stringers with metal stair pans, precast plastic permanent stair treads adhesively attached to the metal pans, and metal risers;

[0067] Fig. 45 is a schematic partial cross sectional view of a closed riser stairway assembly comprising metal stringers with metal stair pans, precast plastic permanent stair treads fixedly attached to the metal / pans and to the stringer; and metal risers;

[0068] Fig. 46 is a schematic partial cross sectional view of a closed riser stairway assembly comprising metal stringers, one piece integral metal stair pans and metal plate risers, with precast plastic permanent stair treads fixedly attached to the stringers by angled support brackets;

[0069] Fig. 47 is a schematic partial cross sectional view of a closed riser stairway assembly comprising metal stringers and angled brackets and flat bars supporting precast plastic permanent stair treads and precast plastic permanent risers on the stringers;

[0070] Fig. 48 is a schematic partial cross sectional view of an open riser stairway assembly comprising metal stringers and metal angle brackets fixedly supporting precast plastic permanent stair treads on the stringers;

[0071] Fig. 49 is a schematic partial cross sectional view of the open riser stairway assembly of Fig. 48, with a precast plastic permanent partial riser fixedly attached to the underside of the front portion of the precast plastic permanent stair tread;

[0072] Fig. 50 is a schematic partial cross sectional view of an open riser stair assembly comprising metal stringers and open riser metal stair pans, the metal stair pan attached to angle brackets, the angle brackets fixedly attached to the metal stringers, each metal stair pan having front slightly downward slanted partial risers and precast plastic permanent stair tread fixedly attached by adhesive to a corresponding metal stair pan;

[0073] Fig. 51 is a schematic partial cross sectional view of the open riser stairway assembly of Fig. 50, where the precast plastic permanent stair treads are fixedly attached by screws to a bracket supporting each metal stair pan on the stringer;

[0074] Fig. 52 is a schematic partial cross sectional view of an open riser stairway assembly comprising metal stringers attached to open riser bent plates, with a precast plastic permanent stair tread fixedly attached to each supporting bracket and to each open riser bent plate;

[0075] Fig. 53 is a schematic partial cross sectional view of an open riser stair assembly comprising metal stringers attached to open riser bracket supports, and precast plastic permanent stair treads fixedly attached to corresponding bracket supports;

[0076] Fig. 54 is a schematic partial cross sectional view of the open riser stairway assembly of Fig. 53 with a precast plastic permanent partial riser fixedly attached to the underside frontal portion of the riser bracket support;

[0077] Fig. 55 is a schematic partial cross sectional view of a stair pan filled closed riser stairway assembly comprising metal stringers with metal stair pans attached to the stringers, with each metal stair pan including a rearwardly mounted metal riser and a precast plastic permanent stair tread and a precast plastic permanent shim of a first thickness located between the metal pan and the stair tread;

[0078] Fig. 56 is a schematic partial cross sectional view of the closed riser stairway assembly of Fig. 55, illustrating a precast plastic permanent shim of a second thickness;

[0079] Fig. 57 is a schematic partial cross sectional view of a closed riser stairway assembly having wooden stringers with metal stair pans attached to the wooden stringers using brackets, front and rear inclined metal riser portions on each metal stair pan, and a precast plastic permanent stair tread adhesively attached to each metal stair pan;

[0080] Fig. 58 is a schematic partial cross sectional view of the stairway assembly of Fig. 57 where the precast plastic permanent stair tread is fixedly attached to the metal stair pan by physical fasteners;

[0081] Fig. 59 is a schematic partial cross sectional view of a closed riser stairway assembly having wooden stringers with a plurality of stair pans supported by brackets to the wooden stringers, and a precast plastic permanent stair tread fixedly attached in each stair pan;

[0082] Fig. 60 is a schematic partial cross sectional view of a closed riser stairway assembly having wooden stringers, with brackets attached to the wooden strings, a precast plastic permanent stair tread fixedly attached to each bracket, and a downwardly extending precast plastic permanent riser fixedly attached to a forward portion of each bracket;

[0083] Fig. 61 is a schematic partial cross sectional view of an open riser stairway assembly having wooden stringers, with angled bracket attached to the wooden stringers and a plurality of relatively thick precast plastic permanent stair treads fixedly attached to each bracket;

[0084] Fig. 62 is a schematic partial cross sectional view of an open riser stairway assembly having wooden stringers, including angled brackets attached to the wooden stringers, a precast plastic permanent stair tread fixedly attached to each bracket, and a precast plastic permanent partial riser fixedly attached to an overhanging front portion of the stair tread;

[0085] Fig. 63 is a schematic partial cross sectional view of an open riser stairway assembly having wooden stringers, including angled brackets attached to the wooden stringers, open riser metal stair pans attached to the brackets with each stair pan having partial risers extending vertically downward at a slight angle from front and rear portions of the metal stair pans, and a precast plastic permanent stair tread adhesively attached to each metal stair pan;

[0086] Fig. 64 is a schematic partial cross sectional alternate view of the open riser stairway assembly of Fig. 63, where the precast plastic permanent stair tread is fixedly attached to the angled brackets by physical fasteners;

[0087] Fig. 65 is a schematic partial cross sectional alternate view of the open riser stairway assembly of Fig. 64, where the partial risers extend substantially vertically downward from the front and rear portions of the metal stair pan;

[0088] Fig. 66 is a schematic partial cross sectional view of an open riser stairway assembly having wooden stringers, including angled brackets attached to the stringers and precast plastic permanent stair treads fixed to and supported by the angled brackets;

[0089] Fig. 66A is a schematic partial cross-sectional alternate view of the embodiment of Fig. 66, with a precast plastic permanent partial riser fixedly attached to the underside frontal portion of the riser support bracket;

[0090] Fig. 67 is a schematic partial cross sectional view of a closed riser stairway assembly having wooden sawtooth stringers, metal stair pans and metal risers, with precast plastic permanent stair treads adhesively attached to each metal stair pan, with screws attaching the metal stair pan to the wooden sawtooth stringers;

[0091] Fig. 68 is a schematic partial cross sectional view of a closed riser stairway assembly having wooden sawtooth stringers, with precast plastic permanent stair treads and risers fixed by screws to the wooden stringer;

[0092] Fig. 69 is a schematic partial cross sectional view of an open riser stairway assembly having wooden sawtooth stringers, with precast plastic permanent stair treads fixed directly to the stringers with screws;

[0093] Fig. 70 is a schematic partial cross sectional view of a stairway assembly having metal stringers and metal risers, with the top riser transitioning to a landing, and where the stair treads and the landing planks comprise precast plastic permanent materials;

[0094] Fig. 71 is a schematic partial cross sectional view of the stairway assembly embodiment of Fig. 70, where the landing planks comprise engaging tongue and groove connections;

[0095] Fig. 72 is a schematic partial cross sectional view of a stairway assembly having metal stringers and metal risers where the top riser transitions to the landing, the landing comprising a concrete slab supported by a metal pan and the stair treads are made of precast plastic permanent material;

[0096] Fig. 73 is a top perspective view of a stairway assembly with precast plastic permanent stair treads attached to metal stair pans with adhesive;

[0097] Fig. 74 is a bottom perspective view of the stairway assembly of Fig. 73;

[0098] Fig. 75 is a bottom perspective view of a stairway assembly with metal stair pans with precast plastic permanent stair treads attached to metal stair pans from beneath the stair pans;

[0099] Fig. 76 is a top perspective view of the stairway assembly of Fig. 75, showing precast plastic permanent stair treads attached to metal stair pans and metal riser plates;

[0100] Fig. 77 is a bottom perspective view of the underside of the stairway assembly of Fig. 76 with fasteners extending from the underside of angled flanges to attach the precast plastic permanent stair treads to the metal stair pans;

[0101] Fig. 78 is a top perspective detail view of a stairway assembly where the leading edge of a metal stair pan engages an embodiment of a precast plastic permanent stair tread;

[0102] Fig. 79 is an end perspective cross section detail view of the stairway assembly of Fig. 78;

[0103] Fig. 80 is a top side perspective view of the metal stringers of a stairway assembly having angled support flanges pre-attached to the stairway stringers;

[0104] Fig. 81 is a top perspective detail view of a stairway assembly having wooden stringers and precast plastic permanent stair treads and partial risers that extend between flanged brackets attached to the wooden stringers;

[0105] Fig. 82 is a bottom perspective detail view of the stairway assembly of Fig. 81;

[0106] Fig. 83 is a top perspective detail view of a stairway assembly having wooden stringers, angled brackets attached to the wooden stringers, and metal bars extending between opposed angle brackets, the metal bars supporting precast plastic permanent stair treads;

[0107] Fig. 84 is a bottom side perspective detail view of the stairway assembly of Fig. 83;

[0108] Fig. 85 is a top perspective view of a stairway assembly having precast plastic permanent stair treads and full risers extending between two wooden stairway stringers;

[0109] Fig. 86 is a bottom perspective view of the stairway assembly of Fig. 85;

[0110] Fig. 87 is a top front perspective view of a stairway assembly having wooden sawtooth stringers, metal stair pans fixedly attached to the wooden stringers, and a precast plastic permanent stair treads adhesively attached to each of the metal stair pans;

[0111] Fig. 88 is a top side perspective view of the stairway assembly of Fig. 87;

[0112] Fig. 89 is a top front perspective view of a stairway assembly having wooden sawtooth stringers, with precast plastic permanent stair treads and full risers attached to the wood stringers; and

[0113] Fig. 90 is a side top perspective view of the stairway assembly of Fig. 89.

[0114] DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

[0115] Fig. 1 illustrates a metal building stairway framework assembly or stairway skeleton 10 that may be installed on the bottom floor of a building under construction, or the bottom floor of a completed building structure where permanent stair treads are required to be installed in place of temporary stair treads that may have been used during construction. Such temporary stair treads are described in U.S. Patents 10,570,623 and 10,676,939. In Fig. 1, stairway framework assembly 10 includes opposed stringers 12, 14 on opposite sides of the stairway 10 and handrails 16, 18 mounted on posts 20, 22. A wire mesh may or may not extend between stringers 12, 14 and reinforcing bars 26, 28 of stairway assembly 10.

[0116] A plurality of substantially flat stair pans 30 extend between stringers 12, 14 and are rigidly attached to stringers 12, 14 at each lateral end of the stair pans. Stair pans 30 are approximately nine to ten inches vertically apart. Certain stair pans have a flat, open front surface, as seen in Fig 44 for example, while other stair pans have a bull nose front end, as seen in Fig. 55-56, for example. Stair pans 30 as are presently available are configured to support either a temporary stair tread, as disclosed in U.S. Patents 10,570,623 and 10,676, 939, or tosupport a permanent or final concrete or concrete-metal stair tread, the latter as disclosed in U.S.Patent 9,169,650.

[0117] Fig. 1 A shows a perspective view of an embodiment utilizing a single stringer stairway assembly 11 from beneath the stairway. A single stringer 13 is shown with a plurality of precast plastic permeant stair treads 32 attached to the single stringer 13. The ingle stringer 13 can be made of metal or wood. The precast plastic permeant stair treads 32 can be attached to the single stringer 13 with brackets, not shown in the figure, or riser wedge plates 15 extending from the single stringer. A handrail 17 is shown with the assembly connected by a plurality of posts 17 to the rest of the single stringer stairway assembly 11. In this embodiment a glass retaining wall 23 supports the posts 17 but this glass retaining wall 23 may be of any material or the posts 17 may connect directly to the precast plastic permeant stair treads 32.

[0118] The present invention relates to several embodiments, uses and stairway assemblies with of precast plastic structurally and fire rated precast permanent plastic stair treads 32, as illustrated in Fig. 2. The stair tread 32 of Fig. 2, and each of the embodiments of stair treads discussed further in this document have a length A, a depth B, and a height C, and radiused comers. The dimensions A, B and C are determined by the size of the stair pan 30 (Fig. 1) onto or into which the stair tread 32 is to be supported or inserted as will be explained. The stair tread 32 can be of any selected color, since the color formulations can be added during the formation process of the precast plastic permanent stair tread 32.

[0119] The precast plastic permanent stair tread 32 shown in Fig. 2, in an embodiment, has an inorganic homogenous solid core structure comprising precast high density polyethylene plastic (HDPE), low density polyethylene plastic (LDPE), and fibrous glass, each of these ingredients being recycled pre-consumer, post-consumer and / or virgin materials. The precastplastic permanent stair tread 32 material can also include inorganic surface binders, foaming agents, UV inhibited additives, antioxidant processing aids, selected colorant additives and / or dye agents, and fire resistant additives. The precast plastic permanent stair tread 32 can be manufactured by any of the following known plastic product production methods, used alone or in combination:

[0120] a. A hybrid process of compression molding and injection molding;

[0121] b. Injection molding;

[0122] c. Compression molding;

[0123] d Extrusion molding (plastification extruding and continuous extruding);

[0124] e. Blow molding;

[0125] f. Thermoforming.

[0126] The precast plastic permanent stair tread 32 as described above provides the strength to support foot traffic loads on a stairway, prevents water absorption and rot, is chemical and termite and insect resistant, and based on inorganic materials to prevent the formation of mold.

[0127] In one embodiment, the precast permanent plastic stair treads 32 are manufactured by feeding molten plastic material that is injected into a cast or mold made preferably of metal.Pressure and vacuum is applied to completely fill the mold or cast, and the plastic is then cooled and cured. Pressure is then applied to remove the cured product from the cast or mold. In an alternate embodiment, a compression molding process can be used to manufacture the stair treads 32. In those embodiments where the stair tread 32 incorporates safety grooves, safety strips, and / or a retrofitted stair nosing, a secondary milling or adhesion process takes place after the casting process is completed.

[0128] The precast plastic permanent stair treads 32, risers and landing planks used in the several embodiments of the presently disclosed stairway assemblies have the approximate following physical / chemical properties that are embedded in an impervious polymer matrix;Specific gravity (H2O=1): 0.60 - 0.90Insoluble in waterMelting point: 255° F - 275° F (124° C - 135° C)Flash point: 640° F - 655° F (338° C - 346° C)Auto-ignition temperature: 820° F - 835° F (438° C - 446° C)Decomposition temperature: 570°F - 600°F (299° C - 316° C)The last four ingredients of stair tread 32 set forth above generally comprise less than six percent of the total plastic composition.

[0129] Fig. 3 illustrates a top plan view of the stair tread 32 of Fig. 2, or a landing plank, and Fig. 4 is a cross-sectional view of stair tread 32 of Fig. 3. As seen in Fig. 4, the front and rear comers 48, 50 are slightly radiused in the range of approximately .1875 inches, since at least one of the edges may be required to nest in a radiused portion where a riser meets a stair pan, as shown in Fig. 55, by way of example.

[0130] The width and thickness of stair tread 32 varies as multiple stair tread profiles are available for supported span and free span capabilities. The radiused corners 48, 50 also allow stair tread 32 to be readily inserted into a bull nose of a metal stair pan configuration to meet certain stairway construction regulations. In an embodiment, the top surface of stair tread 32 comprises a slip resistant texture.

[0131] Fig. 5 is a cross-sectional illustration of an embodiment of a precast plastic permanent stair tread 34 having a foam or partial foam configuration 36 comprising a substantial portion ofthe interior of the stair tread 54. In the illustrated embodiment, an aeration foaming additive is used during formation of the plastic stair tread 34 causing bubbles or hollow spaces to form in the interior of the stair tread 34. This process lessens the weight, adds to the structural rigidity of stair tread 34, the center core is less dense, and the foaming process forces the plastic material to the outer edges of the mold producing a stair tread with higher density around the outer edges. In this embodiment, a chemical reaction is created in the mold with a foaming agent and the aerating process is triggered by a temperature change providing an aerated effect. In another example of this embodiment, small beads made of glass or other materials are added to the molding process for even lighter weight.

[0132] Fig. 6 depicts a precast plastic permanent stair tread 38 or landing plank comprising a solid or a foam core stair tread of two different colors, 40 and 42. All of the presently disclosed precast plastic permanent stair treads described herein are manufactured to be fully recyclable when disposed of when necessary. The colors 40, 42 of the precast plastic designate the type of plastic used in the stair treads, and thus inform the user of the proper disposal protocol regarding the stair tread. Also, stair tread 38 may comprise different textures on the top and bottom surfaces, such as a standard top texture and a bottom grooved or embossed texture.

[0133] Fig. 7 illustrates a precast plastic permanent stair tread 44 comprising a plurality of internally located rebar rods 46 extending along the length A (Fig. 2) of the stair tread 44. Rebar rods 46 may be made of metal, a fiber-reinforced plastic, or any other suitable material that reinforces the strength of stair tread 44. Additionally, rebar rods 46 may be used to reinforce the multi-color stair tread 38 illustrated in Fig. 6.

[0134] Fig. 8 illustrates a precast plastic permanent stair tread 52 comprising anchor apertures 54 in the bottom surface for accepting attachment hardware, as will be explained.

[0135] Fig. 9 illustrates an embodiment of a precast plastic permanent stair tread 56 having a plurality of longitudinally extending channels or grooves 58 on the bottom surface 60 of the stair tread 56. These channels or grooves 58 are configured to receive an adhesive material to bond the underside 60 of stair tread 56 to the upper surface of a stair pan when stair tread 56 is installed in the stair pan. The adhesive material used in this embodiment is an elastomeric joint sealant / adhesive such as sold under the brand name Sikaflex®-! A or other suitable adhesive.The combination of channels or grooves 58 and the adhesive in the channels provide uniform adhesive placement and increased adhesive surface area due to the added surface area of the channels 58.

[0136] Fig. 10 illustrates a precast plastic permanent stair tread 62 comprising one of various top surface configurations 64 to provide slip resistance and / or visual appeal. For example, the top surface 64 could comprise a standard orange peel texture or an embossed wood grain or other non-slip texture. The textures of this embodiment can comprise machined, cast, molded or extruded textures, by way of example.

[0137] Figs. 11 and 12 depict an embodiment of a recyclable precast plastic permanent stair tread 66 having a plurality of parallel safety non-skid grooves 68 extending from the front to the rear of the upper surface 70 of stair tread 66. The amount of grooves 68 may vary. The safety grooves 68 prevent a user's shoes from slipping on the upper surface 70 of stair tread 66. The placement of grooves 68 can vary, such as only at the leading edge, only at the center, or various sizes and spaces between the grooves.

[0138] Figs. 13 and 14 illustrate an embodiment of a recyclable precast plastic permanent stair tread 72 having a plurality of parallel safety anti-skid grooves 74 extending rearward from the front nose 76 of stair tread 72 on upper surface 78 of stair tread 72. In the illustrated embodiment, there are approximately seven parallel anti-skid grooves 74 extending rearward from nose 76, but this amount may vary. Grooves 74 also prevent a user's shoes from slipping on the upper surface 78 of stair tread 72.

[0139] Figs. 15, 16 and 16A illustrate a precast plastic permanent stair tread 80 that accepts a surface mounted metal or plastic nose plate 82 mechanically or adhesively fastened to the nose portion 82 of stair tread 80. Nose plate 82 may comprise a plurality of non-skid ridges 86 on the upper surface, and a plurality of closer-spaced non-skid ridges 88 on the curved front surface of nose plate 82. Nose plate 82 may also comprise an abrasive non-skid material or non-skid grooves, and could also be manufactured from photo luminescent material.

[0140] Figs. 17, 18 and 18A illustrate a precast plastic permanent stair tread 90 having a lengthwise groove 92 adjacent the forward end of the stair tread 90, the groove 92 configured to accept and hold via a flush mount a rectangularly shaped abrasive, ribbed or photo luminescent metal or plastic nosing 94. Nosing 94 may also include non-skid grooves (not shown). Nosing 94 is mechanically or adhesively fastened to stair tread 90 in groove 92.

[0141] Figs. 19, 20 and 20A illustrate an alternate embodiment of the embodiment of Figs.17, 18 and 18 A. In the embodiment of Figs. 19, 20 and 20A, stair tread 96, in addition to nosing94 and groove 92 as described above, includes a plurality of non-skid grooves 98 extending rearwardly a predetermined distance along the depth of the stair tread 96, the grooves 98 beginning adjacent the rear end of nosing 94. Any number of non-skid grooves 98 may be usedin this embodiment. As in the embodiment of Figs. 17, 18 and 18A, the nosing 94 can be formed from an abrasive or ribbed photo luminescent metal or plastic material.

[0142] Figs. 21, 22 and 22A illustrate an embodiment of a precast plastic permanent stair tread 100 including a frontal located channel structure 102 adapted to receive and firmly hold a substantially T-shaped safety strip 104. Stair tread 100 also includes a plurality of parallel safety anti-skid grooves 106 extending from the front to rear of upper surface 108 of stair tread 100. In an embodiment, there are approximately twenty one safety anti-skid grooves 106 on the upper surface 108 of stair tread 100, but this amount may vary.

[0143] Channel 102 extends lengthwise along the front portion 110 of stair tread 100, and includes an upper flat surface 112 disposed a short distance below the plane of upper surface 108 of stair tread 100. Vertical walls 114, 116 define the front and rear edges of channel 102. A slot 118 extends downward from channel 102. Fig. 22A illustrates in detail the plastic colored T- shaped safety strip 104 assembly to be inserted and held in channel 102 of Fig. 22. In an embodiment, non-skid grooves may be eliminated.

[0144] Referring to Fig. 22A, the T-shaped safety strip 104, which is composed of suitable recyclable plastic material, is adapted to be inserted in channel 102 of stair tread 100. Safety strip assembly 104 includes an upper portion 120 with a substantially flat upper surface. A vertical flange 126 extends downward from the underside 124 of upper portion 120, and flange 126 is adapted to be inserted into slot 118 of channel 102 of stair tread 100. In an embodiment, the outer side surfaces of vertical flange 126 are corrugated or otherwise indented to provide added gripping between vertical flange portion 126 and the inner walls of slot 118 (Fig. 22) by providing a compression attachment. A colored safety strip of plastic or other material is firmly attached to the upper surface 120 of T-shaped safety strip assembly 104. The colored safety strip104 may be yellow, or be coated with a luminescent material, depending on what is required to comply with local building codes.

[0145] Figures 23, 24 and 25 illustrate a top plan, a front elevation and a side elevation view, respectively, of a further embodiment of the precast plastic permanent stair tread illustrated in Fig. 2. In the embodiment of Figs. 23, 24 and 25, a frontal groove 130 extends along the length of stair tread 128. Frontal groove 130 allows stair tread 128 to be accepted in a metal bull nose stair pan, such as illustrated in Figs. 55 and 56 by way of example, as an alternate to pan fill concrete. The profile of this embodiment does not include a tapered end cut, since such may not be required to be inserted into the extant metal stair pan.

[0146] Fig. 26 illustrates a further embodiment of the embodiment of the stair tread of Figs. 23, 24 and 25. The precast plastic permanent stair tread 132 of Fig. 26 includes a lengthwise extending second groove 134 in addition to frontal groove 130. The two groove profile of the embodiment of Fig. 26 allows stair tread 132 to be flipped one hundred eighty degrees, providing a construction phase side and an untarnished final finish side.

[0147] Figs. 27, 28 and 29 illustrate a top plan, front elevation and side elevation view, respectively, of a precast plastic permanent stair tread 136 having a frontal groove 138 to accept a metal bull nose stair pan (Figs. 55, 56) as an alternative to pan fill concrete. The embodiment of Figs. 27, 28 and 29, as compared to the embodiment of Figs. 23, 24 and 25 includes tapered end cuts 140 that allow the stair tread 136 to avoid any obstructions that may interfere with insertion of the stair tread 136 into the corresponding metal stair pan.

[0148] Fig. 30 illustrates in cross section a further embodiment of a landing stair plank. In the embodiment of Fig. 30, the precast plastic permanent landing stair plank 142 has an optional foam core 144 (Fig. 5), which foam core may or may not be included in this embodiment.Landing stair plank 142 is made of the same precast plastic material, and produced by the same processes, as the precast plastic permanent stair tread 32 of Fig. 2. In the embodiment of Fig. 30, landing stair plank 142 comprises a tongue 146 along one lengthwise edge, and a groove 148 along an opposing lengthwise edge of the landing stair plank. Figure 31 is an illustration of two landing stair planks 142, as shown in Fig. 30, fitted together using the tongue 146 and groove 148 to form a suitably sized stair and / or deck landing stair plank, as appropriate for the particular stair assembly. Additional planks 142 may be joined together lengthwise in similar fashion as required by the size of the stair landing or deck being constructed or restored. Suitable mechanical or adhesive devices may be used to secure the landing stair planks 142 together in this embodiment.

[0149] Fig. 32 illustrates a cross-sectional view of two precast plastic permanent landing stair planks 150 in an abutting relationship as used in planking stair landings and decks, the latter such as traditional decking.

[0150] Fig. 33 illustrates a cross-sectional view of a precast plastic permanent stair tread 152 where the front longitudinally extending edge incorporates an angled taper 154. This embodiment creates an inline transition from the face of the stair tread 152 to an angle of a frontal vertical portion of a metal stair pan into which the stair tread 152 is inserted or supported. The profile of stair tread 152 also offers two options, where the stair tread 152 can be installed in either direction, with the angled taper or without.

[0151] Fig. 34 illustrates a cross-sectional view of a precast plastic permanent stair tread 156 where both the front and rear longitudinally extending edges each incorporate an angled taper 158. This profile also creates an inline transition from a face of the stair tread to the angle of a vertical portion of a metal stair pan into which the stair tread 156 is inserted or supported.

[0152] Fig. 35 illustrates a cross-sectional view of stair tread 160 where the front longitudinally extending edge 162 incorporates a partial riser 164, the partial riser 164 also comprising precast plastic material. In the illustrated embodiment, partial riser 164 is attached to the underside of stair tread 160 by a screw 165. Alternatively, an adhesive may be used to attach partial riser 164 to the underside of stair tread 160, or the partial riser 164 and stair tread 160 may be formed as one piece by a molding or extruded process. The combination of the stair tread 160 and partial riser 164 increases the structural performance of the stair tread 160, since the partial riser acts as a joist to enhance the stair tread's free span ability. Additionally, the partial riser 164 achieves building code four-inch sphere code requirements, as explained further.

[0153] Fig. 36 illustrates a cross-sectional view of a precast plastic permanent stair tread 166 where the longitudinally extending front edge 168 incorporates a full riser 170 attached to the underside 172 of the stair tread 166. In the illustrated embodiment, a metal angled flange 174 and screws 176 are used to mechanically attach full riser 170 to stair tread 166. Alternatively, adhesive can be used to attach full riser 170 to the underside 172 of stair tread 166, or the full riser 170 and stair tread 166 may be fabricated as a single piece by a molding and / or extruding process. The full riser 170 in the embodiment of Fig. 36 achieves building code four-inch sphere code requirements. In this embodiment, full riser 170 increases structural performance of the stair tread, and acts as a joist to enhance the free span ability of stair tread 166.

[0154] Fig. 37 illustrates a cross-sectional view of a precast plastic permanent stair tread 178 where the front edge 180 incorporates a precast plastic full riser 182 to achieve building code four-inch sphere requirements. The upper end 184 of full riser 182 is inserted into a longitudinally extending rectangular configured groove 186, and is attached firmly in groove 186 by adhesive or mechanical fasteners. Alternatively, the full riser 182 and stair tread 178 can bepre-fabricated as a single precast structure, or delivered to the construction site as separate pieces and assembled on site. The embodiment of Fig. 37 can also be used with a partial riser, for example as shown in Fig. 35. The full riser 182 of the embodiment of Fig. 37 increases the structural performance of stair tread 178, and acts as a joist to enhance the free span ability of the stair tread 178.

[0155] Fig. 38 illustrates an alternate embodiment of the embodiment of Fig. 37 where the underside portion 190 of precast plastic permanent stair tread 188 inches a longitudinally extending female keyhole-shaped groove 192. Full riser 194, also made of precast plastic, includes a corresponding male key 196 that is accepted and held in female keyhole-shaped groove 192 as is known in the art. When assembled as shown in Fig. 38, the stair tread 188 and full riser 194 slide together to create a closed riser-stairway profile to achieve building code sphere code requirements. The same configuration is also applicable to stair treads having partial risers. The stair tread assembly 188, 194 of Fig. 38 increases structural performance, and the full riser 194 acts as a joist to enhance the free spa ability of stair tread 188.

[0156] Figs. 39-41 illustrate several cross-sectional precast plastic permanent stair tread 198 configurations including varying partial riser profiles 200A, 200B and 200C at the front end 202 of each stair tread 198. In each of the embodiments of Figs. 39, 40 and 41, the stair tread 198 and riser 200A, B, C are manufactured as a single piece using a molding and / or extrusion process. Fig. 41 illustrates that a partial riser 200D can also be fabricated at the rear edge 204 of stair tread 198. The partial risers 200A, B, C, D increase structural performance of the stair tread 198 and act as joists to enhance the free span ability of the stair tread 198. Figs. 39-41 also show that the precasting processes used to fabricate the illustrated stair treads 198 are capable ofmanufacturing combined stair treads and partial risers in any desirable and suitable profile configuration in addition to those profiles illustrated and described herein.

[0157] Figs. 42 and 43 illustrate additional cross-sectional profile configurations of the stair treads 198 of Figs. 39, 40 and 41 where full risers 206A, B instead of partial risers extend downward from the front edge 202 of each stair tread 198. In all other aspects, the characteristics and performance qualities of the embodiments of Figs. 42 and 43 are the same as the characteristics and performance qualities of the embodiments of Figs. 39, 40 and 41.

[0158] Fig. 44 is a partial schematic cross-sectional assembly view of a closed riser stairway assembly configuration comprising opposed metal stringers 208 to which a plurality of horizontally extending metal stair pans 210 having a flat surface 212 are attached. Each metal stair pan 210 in the illustrated embodiment comprises a frontal downwardly extending slightly slanted full metal riser 214, and a rearward upwardly extending slightly slanted rear plate 216. The bottom portions of each riser 214 and an upper portion of each corresponding rear plate 216 are welded together in the illustrated embodiment, as shown at 218. The metal stair pan 210 protects against flame. A precast plastic permanent stair tread 32 is supported in each stair pan 210 by adhesive in this embodiment. The pans 210 provide load support.

[0159] Fig. 45 is a partial schematic cross-sectional assembly view of a modified version of the stairway assembly of Fig. 44, where like numbers identify like parts. A plurality of right angled brackets 220 are attached to opposed stringers 208, and metal stair pans 210 are supported by the horizontally extending portion 212 of brackets 220. In the illustrated embodiment of Fig. 45, screws 222 extend through pre-drilled apertures in each bracket 220 and through corresponding pre-drilled apertures in metal stair pan 210 and into precast plastic permanent stair tread 32 to attach the bracket 220, metal stair pan 210 and stair tread 32 in tight engagement witheach other. In this embodiment, the angle of risers 214 and metal stair pan 210 support the load imparted to stair tread 32.

[0160] Fig. 46 is a partial schematic cross-sectional assembly view of a closed riser stairway assembly, illustrating the use of a two-piece bolt-on partial metal stair pan 224 and full riser 226 combined structure to support precast plastic permanent stair treads 32 on the stairway assembly. In the embodiment of Fig. 46, each stairway step 222 comprises a single piece somewhat Z shaped partial stair pan 224 and full riser 226. At the level of each stair step 222, an angled bracket 228 is attached by welding or other suitable attachment device to metal stringer 230. The horizontal portion 232 of each angled bracket 228 includes pre-drilled apertures 234. Pre-drilled apertures 236 are also found in each top and bottom horizontally extending portion of partial stair pan 224, as viewed in Fig. 46, and attachment elements such as screws 239 extend through pre-drilled apertures 234, 236 to fixedly attach precast plastic permanent stair tread 32 to the front and rear partial stair pans 224. As seen in Fig. 46, the rear end of stair tread 32 abuts full riser 226 as riser 226 continues upward to the next stair way 222. In this embodiment, load support is provided by angled brackets 228 and full risers 226, and the need to weld stair pans 224 to the metal stringers 230 at the construction site is eliminated. A space 238 exists beneath the center of the stair tread 32 and partial stair pan 224, as seen in Fig. 46. However, due to its inherent construction as described previously, precast plastic permanent stair tread 32 is sufficiently rigid to prevent flexing in the middle of stair tread 32. In addition, when properly installed, partial stair pans 224 and full risers 226 are made of a relatively thin steel such that any flexing of stair tread 32 in the middle would be so minimal that performance would not be affected, nor would any building code be violated.

[0161] Fig. 47 is a partial schematic cross-sectional assembly view of a closed riser stairway assembly configuration where both the stair tread 32 and a full riser 240 are both made of the precast plastic permanent material as described previously. In this embodiment, angled brackets 242 are fixedly attached to opposed metal stringers 244 by welding or any other suitable process or device. Each stair tread 32 is attached directly to a horizontal portion 246 of a corresponding angle bracket 242 by screws 248 extending through pre-drilled apertures in horizontal portion 246 of angled brackets 242.

[0162] In the embodiment of Fig. 47, full riser 240 is fixedly attached at its top portion to a corresponding forwardly facing flange 252 of angled bracket 242 by screws 254 extending through pre-drilled apertures in flange 252. Full riser 250 extends downward to extend beyond the stair tread 32 of the next lower stair tread assembly. In the embodiment of Fig. 47, the configuration of angled brackets 242 and flange 252 provide load support for the stairway assembly of Fig. 47.

[0163] Fig. 48 illustrates a partial schematic cross-sectional assembly view of an open riser stairway assembly configuration that provides a reduced amount of metal for a free span stairway. When constructing a stairway in a building, one of the code requirements promulgated by the International Code Council, for example, is that riser height shall be not more than seven and three-quarters inches (196 mm) measured vertically between leading edges of adjacent treads. Risers shall be vertical or sloped from the underside of the nosing of the tread above at an angle not more than thirty degrees from the vertical. As to open risers, openings located more than thirty inches (762 mm), measured vertically, to the floor or grade below shall not permit the passage of a four-inch-diameter (102 mm) sphere.

[0164] In the embodiment of Fig. 48, metal angled brackets 256 are attached to opposed metal stringers 258 by means of welding or other suitable attachment devices. A horizontal portion 260 of angled bracket 256 includes pre-drilled apertures 262 through which screws 264 extend to fixedly attach each precast plastic permanent stair tread 32 to horizontal portion 260 of each corresponding angled bracket 256. The vertical distance between forward lower end 264 of each stair tread 32 and the rear upper end 266 of the next lower stair tread 32 is equal to or less than four inches to satisfy building code requirements for open riser stairway assemblies, as described previously. Load support in this embodiment is provided by the angled brackets 256 and the inherent rigidity and strength of precast plastic permanent stair tread 32.

[0165] Fig. 49 is a schematic partial cross-sectional view of an open riser stairway assembly configuration similar to the embodiment of Fig. 48, with the addition of a partial riser 268 attached by screws 270 to the forward longitudinally extending end 272 of each stair tread 32. Partial riser 268 is made of the same precast plastic material as stair tread 32. In this embodiment, the vertical distance between the lower forward edge 274 of each partial riser 268 and the upper rear edge 276 of the next lower stair tread 32 is four inches or less to provide compliance with building codes.

[0166] In all other relevant aspects, the embodiment of Fig. 49 is the same as the embodiment of Fig. 48, where like numerals identify like elements.

[0167] Fig. 50 is a schematic partial cross-sectional view of an open riser stairway assembly configuration using opposed metal stringers 278. In this embodiment, angled brackets 280 are fixedly attached to each stringer 278 by welding or other suitable devices. A metal stair pan 282 in this embodiment is adhesively attached to horizontal portion 284 of each angled bracket 280.Each metal stair pan 282 includes front and rear slightly slanted downwardly extending partial risers 286, 288.

[0168] A precast plastic permanent stair tread 32 is placed on top of and is adhesively attached to each metal stair pan 282. In this embodiment, the vertical distance between the lower end 290 of each front partial riser 286 and the rear upper edge 292 of each stair tread 32 is four inches or less to comply with relevant building codes. In this embodiment, the angled brackets 280 and stair pans 282 provide load support.

[0169] Fig. 51 is a schematic partial cross sectional view of an open riser stairway assembly configuration using opposed metal stringers 278, similar to the embodiment of Fig. 50. In the embodiment of Fig. 51, precast plastic permanent stair tread 32 is fixedly attached to stair pan 282 by screws 294, with screws 294 extending through pre-drilled apertures in angled bracket 280 and in stair pan 282. In all other relevant aspects, the embodiments of Figs. 50 and 51 are similar in configuration and positioning, and like numerals define like elements.

[0170] Fig. 52 is a schematic partial cross-sectional view of an open riser stairway assembly similar to this embodiment of Fig. 51, where like numerals identify like elements. In the embodiment of Fig. 52, each stair pan 282 is replaced with a pair of open riser ninety degree metal bent plates 296 located at the front end and at the rear end of angled bracket 280. Each bent plate 296 includes a horizontally extending portion 298 and a vertically downwardly extending portion 300. The horizontally extending portion 298 of the front and rear bent plates 296 are mounted over the horizontal portion 284 of angled bracket 280, and stair tread 32 is mounted over the front and rear horizontal portions 298 of front and rear bent plates 296. Screws 294 extend through pre-drilled apertures in horizontal portion 294 of each angled bracket 280, and through pre-drilled apertures in the horizontal portions 298 of each bent plate 296 to fixedlyattach stair tread 32 and bent plates 296 to horizontal portion 284 of each corresponding angled bracket 280. As described previously, the vertical distance between the lower end 302 of each vertical portion 300 of the bent plates 296 and the upper rear end 304 of the next lower stair tread 32 is four inches or less to comply with building codes. In this embodiment, the angle brackets provide load support, and as described previously with regard to the embodiment of Fig. 46, the space 306 in Fig. 52 between the front and rear bent plates is minimal such that if stair tread 32 were to flex, such flexing would not affect performance or violate any codes.

[0171] Fig. 53 is a schematic partial cross-sectional view of an open riser stairway assembly similar to the embodiment of Fig. 48 with important modifications, and where like elements are identified by like numerals. In the embodiment of Fig. 53, precast plastic permanent stair tread 32 are fastened to horizontally extending portions 260 of angled brackets 256 with screws 264 extending through pre-drilled apertures 262 in angled brackets 256. As in previous embodiments, angled brackets 256 are welded to metal stringer 258. In this embodiment, each angled bracket 256 includes front and rear downwardly extending flanges 308, 310 respectively. Front flange 308 forms a partial riser that extends downward a sufficient distance between lower end 312 of front flange 308 and the top rear edge of the next lower stair 314 to meet building code requirements as discussed previously. Load support in this embodiment is provided by angled brackets 256 and front and rear flanges 308, 310.

[0172] Fig. 54 is a schematic partial cross-sectional view of an open riser stairway assembly similar to the embodiment of Figs. 53, with an important modification, and where like elements are identified by like numerals. In the embodiment of Fig. 54, angled bracket 256 is welded or otherwise suitably attached to metal stringer 258. A precast plastic permanent stair tread 32 is fixedly attached to horizontally extending portion 260 of each angled bracket 260 by screws 264(middle stair assembly) extending through pre-drilled aperture 262 in horizontal portion 260. In this embodiment, front flange 308 of angled bracket 256 extends vertically downward and a predetermined distance rearward from the front edge 316 of stair tread 32. Vertically extending front flange 308 of each angled bracket 256 includes a pre-drilled aperture 318 through which a screw 320 extends. Screw 320 attaches partial riser 322 to downwardly extending front flange 308, where partial riser 322 is beneath a portion of stair tread 32 that extends beyond the front end of angled bracket 256 defined by front flange 308. As discussed previously, the vertical distance between the lower end 324 of partial riser 322 and the top rear edge 314 of the next lower stair tread 32 is sufficient to meet applicable building codes. In this embodiment, load support is provided by angled bracket 256 and front flange 308. Partial riser 322 is composed of the same material as precast plastic permanent stair tread 32, as discussed previously.

[0173] Fig. 55 is a schematic partial cross-sectional view of a closed riser stairway assembly with precast plastic permanent stair treads 128 of the type illustrated in Figs. 23-25 installed in a metal stair pan 326 and integral full metal risers 328, with an added relatively thin shim 330 located between stair pan 326 and stair tread 128. In this embodiment, shim 330 is made of precast plastic material. In this embodiment, metal stair pans 326 are attached by welding or other suitable means to opposed metal stringers 332 on each opposite lateral sides of each stair pan 326. Each horizontally extending stair pan 326 in the illustrated embodiment includes an integral full riser portion 328 extending vertically at a slight slant with a horizontal portion 334 of riser portion 328 comprising a bull nose feature 336 of the integral metal stair pan 326 and full riser 328. As seen at 338, metal stair pan 326 is fixedly attached to full riser 328 by welding or by any other suitable process or device.

[0174] As seen in Fig. 55, precast plastic permanent stair tread 128 is inserted into and supported by stair pan 326. When inserted, frontal groove 130 of stair tread 128 is inserted under horizontal portion 334 of full riser 328, such that the forward end 340 of stair tread 128 is protected by bull nose feature 336. In the illustrated embodiment of Fig. 55, the vertical depth of stair pan 326 from its surface facing stair tread 128 to horizontal portion 334 of full riser 328 is in the range of one and a half inches. A relatively thin shim 330 is located between the surface of stair pan 326 facing stair tread 128 and stair tread 128. Shim 330 is fastened to the surface of stair pan 326 facing stair tread 128, and shim 330 is attached to the underside of stair tread 128 by adhesive fasteners.

[0175] Fig. 56 is a schematic partial cross-sectional view of a closed riser stairway assembly similar to the embodiment of Fig. 55, the difference being that the vertical depth of stair pan 326 is two inches or more. Other than the depth of stair pan 326 and the height of shim 342, all of the features and elements of Fig. 56 are the same as Fig. 55. Like numerals in Figs. 55 and 56 identify the same elements in each embodiment.

[0176] Fig. 57 is a schematic partial cross-sectional view of a closed riser stairway assembly configuration embodying opposed wooden stringers 344 to which a plurality of angled brackets 346 are attached by nut and bolt fasteners 348 extending through pre-drilled oblong slots 350 in angled bracket 346. The oblong configuration of slots 350 allows the front to rear position of each angled bracket 346 to be horizontally adjusted, if necessary, to meet applicable building codes.

[0177] Each angled bracket 346 has a horizontally extending portion 352 that supports a metal stair pan 354, with each stair pan 354 comprising a flat surface 356. Each metal stair pan 354 in the illustrated embodiment also comprises a frontal downwardly extending slightlyslanted full metal riser 358, and a rearward upwardly extending slightly slanted rear plate 360. The bottom portions of each riser 358 and an upper portion of each corresponding rear plate 360 are welded together in the illustrated embodiment, as shown at 362. The metal stair pan protects against flame. A precast plastic permanent stair tread 32 is supported on flat surface 356 of each stair pan 354, and is held in place by adhesive in the illustrated embodiment. Load support in this embodiment is provided by angled brackets 346 and metal stair pans 354.

[0178] Fig. 58 is a partial schematic cross-sectional assembly view of a modified version of the wooden stringer stairway assembly of Fig. 57, where like numerals identify like parts. A plurality of right angled brackets 346 are attached to the each opposed wooden stringer 344 by fasteners 348 extending through pre-drilled oblong slots 350 to fixedly attach each opposed right angled bracket 346 to the wooden stringer 344. Metal stair pans 354 are supported by the horizontally extending portions 352 of right angled brackets 346, and the metal stair pans 354 are configured and assembled as described regarding the embodiment of Fig. 57. In the embodiment illustrated in Fig. 58, screws 364 (shown in middle stairway assembly of Fig. 58) extend through a pair of pre-drilled apertures in each of the horizontal portions 352 of right angled bracket 346, through corresponding pre-drilled apertures in metal stair pan 354, and into precast plastic permanent stair tread 32 to attach stair tread 32, metal stair pan 354 and right angle bracket 346 into tight engagement with each other. In this embodiment, load support is provided by right angled bracket 346 and stair pan 354.

[0179] Fig. 59 is a partial cross sectional assembly view of a closed riser stairway assembly comprising opposed wooden stringers 366 and a plurality of two-piece bolt-on partial metal stair pans 368. The embodiment illustrated in Fig. 59 is similar in substantially all aspects to the embodiment of Fig. 46, with the exception that each right angled bracket 370 of Fig. 59 isfixedly attached to an opposed wooden stringer 366 with nut and bolt fasteners 372 extending through oblong slots 372. In all other aspects and attributes, the detailed description of the embodiment of Fig. 59 is the same as the previously detailed description of the embodiment of Fig. 46, and like numerals where applicable identify like elements. In the embodiment of Fig. 59, load support is provided by right angled bracket 370, metal stair pan structures 368 and full risers 226.

[0180] Fig. 60 is a partial cross-sectional assembly view of a closed riser stairway assembly having wooden stringers 376. The embodiment of Fig. 60 is substantially similar to the embodiment of Fig. 47, with the exception that in the embodiment of Fig. 60, the angled brackets 378 are fixedly attached to each wooden stringer 376 by nut and bolt fasteners 380 extending through oblong slots 382 and into wooden stringers 376, and stringers 376 are wood rather than metal. In all other aspects and attributes the detailed description of the embodiment of Fig. 60 is the same as the previous detailed description of the embodiment of Fig. 47, and like numerals, where applicable, identify like elements. In the embodiment of Fig. 60, load support is provided by angled bracket 378 and flange 252 of angled bracket 378.

[0181] Fig. 61 is a partial cross-sectional assembly view of an open riser stairway assembly comprising opposed wooden stringers 384. The embodiment of Fig. 61 is substantially similar to the embodiment of Fig. 48, with the exception that in the embodiment of Fig. 61, each angled bracket 386 is fixedly attached to each opposed wooden stringer 384 by nut and bolt fasteners388 extending through oblong slot 390 and into wooden stringer 384, and stringers 384 are wood rather than metal. In all other aspects and attributes, the detailed description of the embodiment of Fig. 61 is the same as the previous detailed description of the embodiment of Fig. 48, and likenumerals where applicable identify like elements. In the embodiment of Fig. 61, load support is provided by horizontal portions 160 of angled bracket 386.

[0182] Fig. 62 is a partial cross-sectional assembly view of an open riser stairway assembly comprising opposed wooden stringers 392. The embodiment of Fig. 62 is substantially similar to the embodiment of Fig. 49, with the exception that in the embodiment of Fig. 62, each angled bracket 394 is fixedly attached to a wooden stringer 392 by nut and bolt fasteners 396 extending through oblong slot 398 and into wooden stringer 392, and stringers 392 are wood rather than metal. In all other aspects and attributes, the detailed description of the embodiment of Fig. 62 is the same as the previous detailed description of the embodiment of Fig. 49, and like numerals identify like elements. In the embodiment of Fig. 62, load support is provided by angled bracket 394.

[0183] Fig. 63 is a partial cross-sectional assembly view of an open riser stairway assembly comprising opposed wooden stringers 400. The embodiment of Fig. 63 is substantially similar to the embodiment of Fig. 50, with the exception that in the embodiment of Fig. 63, each angled bracket 402 is fixedly attached to a wooden stringer 400 by nut and bolt fasteners 404 extending through an oblong slot 406 and into wooden stringer 400, and stringers 400 are wood rather than metal. In all other aspects and attributes, the detailed description of the embodiment of Fig. 63 is the same as the previous detailed description of the embodiment of Fig. 50 and like numerals identify like elements. In the embodiment of Fig. 63, load support is provided by angled bracket 402 and stair pan 282.

[0184] Fig. 64 is a partial cross-sectional assembly view of an open riser stairway assembly comprising opposed wooden stringers 392. The embodiment of Fig. 64 is substantially similar to the embodiment of Fig. 51, with the exception that in the embodiment of Fig. 64, each angledbracket 408 is fixedly attached to a wooden stringer 406 by nut and bolt fasteners 410 extending through oblong slot 412 and into wooden stringer 406, and stringers 406 are wood rather than metal. In all other aspects and attributes, the detailed description of the embodiment of Fig. 64 is the same as the previous detailed description of the embodiment of Fig. 51 and like numerals identify like elements. In the embodiment of Fig. 64, load support is provided by angled bracket 408 and metal stair pan 282.

[0185] Fig. 65 is a partial cross-sectional assembly view of an open riser stairway assembly comprising opposed wooden stringers 414. The embodiment of Fig. 65 is substantially similar to the embodiment of Fig. 52, with the exception that in the embodiment of Fig. 65, each angled bracket 416 is fixedly attached to a wooden stringer 414 by nut and bolt fasteners 418 extending through oblong slot 420 and into wooden stringer 414, and stringers 414 are wood rather than metal. In all other aspects and attributes, the detailed description of the embodiment of Fig. 65 is the same as the previous detailed description of the embodiment of Fig. 52, and like numerals identify like elements. In the embodiment of Fig. 65, load support is provided by angled bracket 416.

[0186] Fig. 66 is a partial cross-sectional assembly view of an open riser stairway assembly comprising opposed wooden stringers 422. The embodiment of Fig. 66 is substantially similar to the embodiment of Fig. 53, with the exception that in the embodiment of Fig. 66, each angled bracket 424 is fixedly attached to a wooden stringer 422 by nut and bolt fasteners 426 extending through oblong slot 428 and into wooden stringer 422, and stringers 422 are wood rather than metal. In all other aspects and attributes, the detailed description of the embodiment of Fig. 66 is the same as the previous detailed description of the embodiment of Fig. 53, and like numeralsidentify like elements. In the embodiment of Fig. 66, load support is provided by angled bracket424 and flanges 308 and 310.

[0187] Fig. 66A is a schematic partial cross-sectional assembly view of an open riser stairway assembly comprising opposed wooden stringers 423 to which a plurality of angled brackets 425 are attached, in the illustrated embodiment, with nut and bolt assemblies 427 to opposed wooden stringers 423. Nut and bolt fastener assemblies 427 extend through oblong apertures 429. Precast plastic permanent stair tread 32 is attached to horizontal portion 431 of angled bracket 425 in the illustrated embodiment by screws 433 (middle stair assembly) extending through pre-drilled apertures 435 in horizontal portions 431 of angled brackets 425. Front flange 437 of each angled bracket 425 extends vertically downward and a predetermined distance rearward from the front edge 439 of stair tread 32. Vertically extending front flange 437 of each angled bracket 425 includes pre-drilled apertures 441 through which screws 443 extend to attach partial risers 445 to front flange 437, such that partial risers 445 are each beneath a portion of stair tread 32 that extends forwardly beyond the front face of flange 437. In this embodiment, the vertical distance between the lower end 447 of partial riser 445 and the top rear edge 449 of the next lower stair tread 32 is sufficient to meet applicable building codes. In this embodiment, load support is provided by angled bracket 425 and partial riser 445. Partial riser 445 is made of the same precast plastic material as precast plastic permanent stair tread 32.

[0188] In the illustrated embodiment of Fig. 66A, a surface mounted nose plate 451 is mechanically or adhesively fastened to the nose portion 453 of stair tread 32. Nose plate 451 may comprise a plurality of non-skid ridges 455 on the upper surface, and a plurality of closerspaced non-skid ridges 457 on the curved front surface of nose plate 451. Nose plate 451 mayalso comprise an abrasive non-skid material or non-skid grooves, and could also be manufactured from photo luminescent material.

[0189] Fig. 67 is a partial schematic cross-sectional view of a closed riser stairway assembly configuration comprising opposed wooden sawtooth shaped stringers 430 to which a plurality of metal stair pans 432 are directly attached to the horizontal portions 434 of sawtooth stringers 430 by wood screws 436 in the illustrated embodiment. A precast plastic permanent stair tread 32 is adhered by an adhesive to each stair pan 432. As in the embodiment of Fig. 44, each metal stair pan 432 in the embodiment of Fig. 67 comprises a frontal downwardly extending slightly slanted full metal riser 438, and a rearward upwardly extending slightly slanted rear plate 440. The bottom portions of each riser 438 and an upper portion of each corresponding rear plate 440 are welded together in the illustrated embodiment, as shown at 442. The metal stair pan 432 protects against flame. In the embodiment of Fig. 67, load support is provided by the horizontal portions 434 of sawtooth wooden stringers 430, and by metal stair pans 432.

[0190] Fig. 68 is a partial schematic cross-sectional view of a closed riser stairway assembly configuration comprising opposed wooden sawtooth shaped stringers 444 to which a plurality of precast plastic permanent stair treds 32 are attached by wood screws 446 to the horizontal portions 448 of sawtooth wooden stringer 444 by wood screws 450. Further, a plurality of precast plastic permanent longitudinally extending full risers 452 are attached to vertical portion 454 of wooden sawtooth stringers 444 by wood screws 456. As seen in Fig. 68, wood screws 450 and 456 extend through the precast plastic material of stair treads 32 and of full risers 452 to attach the stair tread 32 and the riser 452 to the sawtooth shaped wooden stringer 444. In addition, wood screws 458 extend through a frontal portion 460 of each stair tread 32 and through an upper end 462 of an adjacent riser 452 to attach each stair tread 32 to an abutting fullriser 452. In this embodiment, load support is provided by the sawtooth wooden stringers 444, the horizontal stair tread 32, and the vertical full riser 452.

[0191] Fig. 69 is a partial schematic cross-sectional view of an open riser stairway assembly configuration comprising opposed wooden sawtooth shaped stringers 464 having horizontally extending portions 466 and a precast plastic permanent stair tread 32 attached to each horizontally extending portion 466 by wood screws 468. As seen in Fig. 69, the rearward end 170 of each stair tread 32 abuts against vertical portion 472 of wooden sawtooth stringer 464. In this embodiment, load support is provided by the opposed wooden sawtooth stringers 464.

[0192] Fig. 70 is a partial schematic cross sectional view of a stairway and landing transition assembly configuration where the top riser makes a transition to the landing 476. In the illustrated embodiment, a plurality of metal stair pans 472 are fixedly attached to each opposing metal stringer 474 by welding or other suitable means. Each of the stair pans 472 comprises a frontal downwardly extending slightly slanted full metal riser 478 and a rearwardly upwardly extending slightly slanted rear plate 480. The bottom portion of each riser 478 and an upper portion of each corresponding rear plate 480 are welded together in the illustrated embodiment, as shown at 482.

[0193] Landing 476, in the illustrated embodiment, comprises a relatively thick beam 484 supporting a flat stair pan 486, the latter extending in one piece across landing 476. In this embodiment, flat stair pan 486 is aligned with the top horizontal portion 488 of the uppermost full metal riser 478. Flat stair pan 486 is supported by the upper flat surface of landing 476. Also in this embodiment, a plurality of precast plastic permanent landing planks 490 are secured in an abutting array to the flat surface of flat stair pan 486 by adhesive or other known fasteningmeans. In this embodiment, the horizontal portion 488 of uppermost full metal riser 478 completes a standard transition from the stairway assembly to landing planks 490.

[0194] Fig. 71 is a partial schematic cross-sectional view of a stairway and landing transition assembly configuration similar to the stairway and landing transition assembly of Fig. 70, where like numerals identify like elements. In the embodiment of Fig. 71, the uppermost full metal riser 492 has a relatively short horizontally extending portion 494 defining a space 496 beneath horizontally extending portion 494 of full metal riser 492. In this embodiment, a plurality of landing planks 498 are assembled together by tongue and groove connectors 500. The forwardmost tongue 502 of the plurality of landing planks 498 is inserted in space 496 such that the top of horizontal extending portion 494 is in alignment with the top surfaces of each landing plank 498. In this embodiment, horizontal extending portion 494 of full metal riser 492 extends into space 496, thus removing tongue 502 as a tripping hazard. In this embodiment, the horizontal extending portion 494 of full metal riser 492 completes a standard transition from the stairway assembly to landing planks 498.

[0195] Fig. 72 is a partial schematic cross-sectional view of a stairway and landing transition assembly configuration similar to the embodiments of Figs. 70 and 71, where like numerals identify like elements. In the embodiment of Fig. 72, angled bracket 504 is fixedly attached to metal stringer 508 by welding or other suitable means as are known in the art. A horizontally extending portion 510 of angled bracket 504 supports a landing structure 506, which in the illustrated embodiment is a one piece or multiple piece flat topped concrete landing structure.Landing structure 506 could also comprise any other material or composition of materials known in the art of producing stairway landing structures. In this embodiment, it is contemplated thatlanding structure 506 is furnished at the construction site by a supplier other than the contractor building the stairway assembly of Fig. 72.

[0196] In the embodiment of Fig. 72, the top of full metal riser 492 includes a relatively short horizontally extending portion 494 that fits into a longitudinally extending groove 512 of landing structure 506 such that the top surface of horizontally extending portion 494 is flush with the top surface of landing structure 506. In this way, the transition from the stairway assembly to the top of landing structure 506 is smooth and free of tripping hazards.

[0197] Figs. 73, 74 and 75 are front, bottom side, and bottom rear perspective views of a stairway assembly 514 having opposed metal stringers 516 to which metal stair pans 518 are attached using angled brackets 520 as previously set forth regarding earlier illustrated metal stringer embodiments. Metal stair pans 518 protect precast plastic permanent stair treads 32 from fire underneath, and also provide structural support for the horizontal span of the stair tread 32. Traditionally, the metal stair pan 518 can be prefabricated in shop with the stair tread 32 attached at the shop, or the stair tread 32 can be installed after the metal stair pans 518 are installed at the construction job site. In the embodiments of Figs. 73 and 74, the illustrated stair tread 32 is attached to metal stair pan 518 by adhesives. In the embodiment of Fig. 75, mechanical fasteners 522, such as a bolt assembly or screws, or the like are used. Mechanical fasteners 522 in this embodiment are installed from the bottom of metal stair pans 518 and extend into the bottom of each corresponding stair tread 32. Pre-drilled apertures can be formed in metal stair pans 518 and / or stair treads 32 for ease of assembly.

[0198] Figs. 76 and 77 are front and rear perspective views, respectively of an embodiment of a stairway assembly 514 comprising opposed metal stringers 526 and including metal risers 528 providing structural support for the longitudinal span of precast plastic permanent stairtreads 32, and the riser 528 also closes the openings between stair treads 32 when required. Fig.76 illustrates the top side of stairway assembly 524 with precast plastic permanent stair treads 32 attached to metal stringers 526 and metal riser plates 528 as previously described. Stair treads 32 are attached to angled brackets 530 (Fig. 77). In this embodiment, referring to the underside view of Fig. 77, angled brackets 530 are pre-attached to opposed metal stringers 526. Mechanical fasteners (not shown), such as nut and bolt assemblies, metal screws or the like, are inserted from the underside through pre-drilled apertures in angled brackets 530 and in horizontally extending portions of metal stair riser plates 528 and into the underside of stair treads 32 to complete the stairway assembly.

[0199] Figs. 78 and 79 are detail perspective cut-away top side forward leading edge views of an embodiment of the longitudinally extending precast plastic permanent stair tread 128 (Figs. 23-25) having a frontal groove 130. Frontal groove 130 is inserted into a space beneath a pan nose 535 (Fig. 79) formed by horizontally extending portion 532 of a vertical riser 534. Stair tread 128 is supported in metal stair pan 536 that is suitably attached, such as by welding at 538, to opposed metal vertical riser 534. Stair tread 128 is attached with adhesive or setting mortar to provide a flush transition from pan nose 535 to the top surface of stair tread 128.

[0200] Fig. 80 is a perspective view of opposed metal stringers 538 having a plurality of opposed angled brackets 540 attached or pre-attached, such as by welding or the like, to the opposed metal stringers 538. In the illustrated embodiment, a precast plastic permanent stair tread 32 is installed at the bottom of the stairway assembly. The assembly process of Fig. 80 can be carried out at the construction job site.

[0201] Figs. 81 and 82 are front top and front bottom perspective views, respectively, of wood stair stringers 542, that could also be metal stringers if desired, with angled brackets 544(Fig. 82) directly supporting precast plastic stair treads 32 between opposed wood stringers 542. Each stair tread 32 includes a front leading edge closure profile 546 made of the same material as stair tread 32, which closure profile 546 partially closes the riser gap 548. Closure profile 546 also provides additional support for the free span of stair tread 32 between stringers 542, as an alternative to attempts to free span precast concrete stair treads used previously.

[0202] Fig. 81 illustrates the top view of the stair tread 32 mounted for free span between opposed metal or wood stringers 542. The underside view of this embodiment illustrates angled brackets 544 connecting each stair tread 32 at both ends to stringers 542, using mechanical fasteners 550 inserted from the underside through pre-drilled apertures in angled brackets 544 and into the underside of stair tread 32 for attachment at each step.

[0203] Figs. 83 and 84 are front top and front bottom perspective views, respectively, of a further embodiment of attaching precast plastic permanent stair treads 32 to opposed stringers 552, which stringers are illustrated as made of wood but also could be metal stringers. In the illustrated embodiment of Figs. 83 and 84, angled brackets support stair treads 32 as in several previous partially open riser embodiments. A metal angled strip 554, bent plate (not shown) or lengthwise extending bar (not shown) are located at the front and rear spanning edges of each stair tread 32 to support the span of tread 32 when tread 32 is a relatively thinner version of the stair tread, such as one-and-a-half inch thick. The metal angled strip 544 and bent plate will close the riser gap 556 when required. This stairway embodiment can be pre-fabricated in shop and product shop installed, or the stair tread 32 can be installed during stair insulation on the job site.

[0204] Fig. 83 illustrates the stair tread 32 free span between wood or metal stringers 552. Fig. 84 illustrates the underside of Fig. 83, showing angle brackets 558 connected to each stringer 552 using mechanical fasteners 560 from underside through pre-drilled apertures inangled brackets 558. The mechanical fasteners 560 extend into the underside of stair tread 32 to attach each stair tread 32 to a pair of corresponding opposed angled brackets 558. Metal angle, bent plate or bar 554 at the spanning front and rear edges of the stair tread 32 support the span of the thinner version of stair tread 32 and close the riser gap 562 (Fig. 83) when required. As seen in Fig. 84, metal angle, bent plate or bar 554 is attached to opposed angled brackets 558 by mechanical fasteners 564.

[0205] Figs. 85 and 86 are top front and front bottom perspective views, respectively, of a further embodiment of attaching precast plastic permanent stair treads 32 to opposed wooden or metal stringers 568. In the embodiment of Figs. 85 and 86, angled brackets 566 are attached to stringers 568 by mechanical fasteners 570. If metal stringers 568 are used, angled brackets 566 may be welded to stringers 568. Free spanning stair treads 32 are directly attached to angled brackets 566 by mechanical fasteners 572, as seen in Fig. 86. In the illustrated embodiment, stair tread 32 has a relatively thicker profile, such as a thickness in excess of two inches for example. A full riser 574 made of the same material as stair treads 32, but of a relatively smaller thickness, such as one and one-half inches forms full riser 574 that extends vertically in the gap between two sequential stair treads 32, as seen in Fig. 85. Full riser 574 adds additional free span support for stair tread 32. In this embodiment, a longitudinally extending metal bar 576 (Fig. 86) to which full riser 574 is attached also provides load support for stair tread 32.

[0206] Figs. 87 and 88 are front top and front side perspective views, respectively, of precast plastic permanent stair treads 32 (Fig. 87), each stair tread 32 installed in a metal stair pan 578 of a sawtooth wooden stairway assembly 580. In the illustrated embodiment, metal stair pans 578 are assembled together, such as by welding, such as metal stair pans 210 shown in Fig. 44. If desired, other metal stair pan assemblies can be used in the embodiment of Figs. 87 and 88. Theembodiments of Figs. 87 and 88 comprise a traditional wood sawtooth stringer 582 construction. Traditionally, sawtooth wooden stairways utilize plywood treads and risers covered with finish materials such as carpet or rubber cover. In the present embodiment, precast plastic permanent stair tread 32, as shown in Fig. 87, is installed as an alternative to those finish materials. In this embodiment, metal stair pans 578 are attached to the wood stringers 582 with wood screws (not shown), and each stair tread 32 is attached to a metal stair pan 578 by a suitable adhesive. Fig. 88 is a side view showing metal stair pans 578 without stair tread 32 installed.

[0207] Figs. 89 and 90 are front top and front side perspective views, respectively, of precast plastic permanent stair treads 32 and precast plastic permanent full riser closures 586 installed directly to the wood sawtooth stringers 588, such as wood sawtooth stringers 582 in Figs. 87 and 88. In the illustrated embodiment of Figs. 89 and 90, each stair tread 32 is attached with adhesive and / or mechanical fasteners to the horizontal opposed portions 590 of wood sawtooth stringers 588. Full precast plastic riser closures 586 are attached with adhesive and / or mechanical fasteners (not shown) to the vertical opposed portion 592 of wood sawtooth stringers 588.

[0208] While the present disclosure has been described in connection with certain embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.

Claims

Claims:

1. A permanent stair tread for installation in a building stairway structure, the stairway structure including at least one of a single stringer and opposed stringers, comprising; the permanent stair tread configured to be supported by at least one of said stringers; the permanent stair tread having a core structure, the core structure composed of inorganic materials in the range of greater than ninety four percent and up to and including one hundred percent.

2. The permanent stair tread of claim 1, wherein; the core structure is composed of a precast composition of high density polyethylene plastic (HDPE), low density polyethylene plastic (LDPE), and fibrous glass, wherein each of these ingredients are at least one of recycled pre-consumer, post-consumer and virgin materials.

3. The permanent stair tread of claim 1, wherein; the permanent stair tread composition includes at least one surface binder, at least one foaming agent, at least one UV inhibited additive, at least one antioxidant processing aid, at least one selected colorant additive and / or dye agent, and at least one fire resistant additive.

4. The permanent stair tread of claim 1, wherein; the permanent stair tread has a specific gravity (H2O=1) in the range of 0.60 - 0.90, is insoluble in water, has a melting point in the range of 255° F - 275° F (124° C - 135° C), a flash point in the range of 640° F - 655° F (338° C - 346° C), an auto-ignition temperature in the range of 820° F - 835° F (438° C - 446° C), and a decomposition temperature in the range of 570°F - 600°F (299° C - 316° C).

5. The permanent stair tread of claim 1, wherein;the permanent stair tread has a melting point of 266° F (130° C), a flash point of 644° F (340° C), an auto-ignition temperature of 824° (440° C), and a decomposition temperature of 572°F (300° C).

6. The permanent stair tread of claim 1, wherein; the permanent stair tread has a height, width, and depth dependent on the height, width, and depth of a stairway pan structure.

7. The permanent stair tread of claim 1, wherein; the permanent stair tread is configured to be at least one of a stairway landing plank and a stairway platform plank.

8. The permanent stair tread of claim 1; said permanent stair tread having hollow spaces in said core structure of said permanent stair tread.

9. The permanent stair tread of claim 1; said core structure comprising at least two different colored inorganic materials, each color designating the type of core material comprising the permanent stair tread.

10. The permanent stair tread of claim 1; said core structure comprising at least one rebar rod extending lengthwise through one of all and a portion of said core structure.

11. The permanent stair tread of claim 1; said permanent stair tread comprising a non-slip textured upper surface.

12. The permanent stair tread of claim 1; an upper surface of said permanent stair tread including a plurality of non-skid grooves arrayed along one of the entire upper surface and a portion of the upper surface.

13. The permanent stair tread of claim 1; a front portion surface of said permanent stair tread having one of a metal and plastic nose plate attached to said front portion surface, said nose plate including a plurality of nonskid ridges on an upper surface of said nose plate.

14. The permanent stair tread of claim 13; said upper surface of said nose plate including photo luminescent material.

15. The permanent stair tread of claim 1; an upper surface of a front portion of said permanent stair tread including a lengthwise groove, at least one of a flush mounted abrasive, ribbed, and photo luminescent nosing structure adhered in said lengthwise groove to said permanent stair tread.

16. The permanent stair tread of claim 1, a front portion of said permanent stair tread including a lengthwise channel, a slot extending downward from said channel, a T-shaped safety strip inserted in said channel, an underside of said T-shaped safety strip including a downwardly extending flange removeably extending into said slot.

17. The permanent stair tread of claim 1; said permanent stair tread having one of a lengthwise frontal groove and both a lengthwise frontal groove and a lengthwise rearward groove, the lengthwise frontal groove disposed on an upper surface of said permanent stair tread, said lengthwise rearward groove disposed on a bottom surface of said permanent stair tread, said lengthwise frontal and rearward grooves adapted to be accepted in a bull nose of a metal stair pan.

18. The permanent stair tread of claim 1;said permanent stair tread having lengthwise extending tapered end cuts.

19. The permanent stair tread of claim 7, wherein: the permanent stair tread is one of a landing plank and a platform plank; the one of the landing plank and platform plank having a lengthwise extending tongue at one side end of the plank and a groove at an opposite side end of said plank; the tongue of one plank configured to extend into the groove of an adjacent plank to form one of said landing and said platform.

20. The permanent stair tread of claim 1, wherein: one of a lengthwise extending frontal edge, and both the lengthwise extending frontal edge and a lengthwise extending rearward edge, incorporate an angled taper extending from an upper surface of the permanent stair tread to a lower surface of the permanent stair tread.

21. The permanent stair tread of claim 1, wherein: one of a partial riser and a full riser extends downward from an underside of said permanent stair tread.

22. The permanent stair tread of claim 21, wherein: the one of the partial riser and the full riser comprises the same core structure composition as the permanent stair tread.

23. The permanent stair tread of claim 21; said one of said partial riser and said full riser integrally formed with said permanent stair tread.

24. A stair assembly, comprising; one of a single stringer and a pair of opposed stringers;a plurality of stair pan structures supported by said one of a single stringer and said pair of opposed stringers; each said stair pan structure having a substantially flat upper surface; a permanent stair tread disposed on and supported by said flat upper surface of each said stair pan structure; each said permanent stair tread having a core structure composed of inorganic materials in the range of greater than ninety four percent and up to and including one hundred percent.

25. The stair assembly of claim 24, including; one of a full riser and a partial riser extending between adjacent stair pan structures.

26. The stair assembly of claim 24, wherein; each said permanent stair tread is adhesively connected to each corresponding said stair pans structures.

27. The stair assembly of claim 24, wherein;Each permanent stair tread is mechanically connected to each corresponding said stair pan structures with an angled bracket and at least one mechanical fastener.

28. The stair assembly of claim 24, wherein; the stringers are comprised of wood, said stair pan structures mechanically connected to the wood stringer.

29. The stair assembly of claim 28, wherein; said wooden stringer have a sawtooh configuration.

30. The stair assembly of claim 24, wherein; a shim is disposed between each said stair pan structures and each corresponding permanent stair tread installed in said stair pan structure.

31. A stair assembly, comprising; one of a single stringer and a pair of opposed stringers; a plurality of angled brackets connected to the stringers; the plurality of angled brackets having a substantially flat horizontal surface, a permanent stair tread attached to the substantially flat horizontal surface of each angled bracket, the permanent stair tread one of mechanically and adhesively connected to a corresponding angled bracket; said permanent stair tread having a core structure composed of inorganic materials in the range of greater than ninety four percent and up to and including one hundred percent.

32. The stair assembly of claim 31, wherein; one of a full riser and a partial riser extends between each permanent stair tread.

33. The stair assembly of claim 31, wherein; the stringers are comprised of wood and the stringers having a sawtooth configuration.

34. The stair assembly of claim 31 , wherein; the one of a single stringer and a pair of opposed stringers are comprised of metal.

35. The stair assembly of claim 31, wherein; the one of a single stringer and a pair of opposed stringers are comprised of wood.