A light gauge steel building construction system

Abstract

Onsite building construction with traditional methods tends to progress slowly due to the sequential nature of the process. With the skilled trades shortage and the need for more affordable housing, present methods cannot build enough housing to meet the demand. This invention provides a new building construction system and method by combining off-site and on- site techniques. Prefabricated cold-formed light gauge steel (LGS) wall panels finished with insulation, windows, weather barrier membranes, siding and claddings are transported and installed on-site. A composite floor system is fabricated on-site with prefabricated cold-formed LGS joists and pre-cut OSB and plywood boards. MEPs are conveniently installed through floors and walls on-site. Same floor system also acts as a flat roof. This technology could be used to construct low-rise residential, commercial, and industrial buildings at a considerably faster speed and rate than conventional methods.

Description

Title of invention: Light Gauge Steel Building Construction System and MethodTechnical field

[0001] The present invention relates to a building construction system and method. More particularly, it relates to a prefabricated light gauge steel frame (LGSF) building construction system and method.Background art

[0002] In countries where wood is abundant, traditional home and building construction methods involve carrying and transporting almost all building materials to the construction site. The majority of work is carried out on-site in all weathers. These conditions negatively impact the speed of construction and the productivity of workers. From pouring a concrete foundation, to framing, to installing mechanical, electrical and plumbing (MEPs) equipment and insulation, to hanging and painting drywall, to installing windows and doors, to siding and cladding the exterior and roofing, and finally to flooring and installing finishing fixtures and appliances, each stage requires workers highly skilled in that particular trade. Work usually entails measuring and cutting to length all materials on-site and installing components using and operating a variety of power tools. Workers operating these tools face serious occupational hazards if not properly trained. A sizeable portion of the original building materials goes to waste after cutting as the leftover pieces may not be suitable for use anymore.

[0003] In other countries where wood is scarce and more expensive, cheaper but heavier alternative building materials like concrete, clay bricks, cinder blocks, and steel are commonly used in home and building construction. Buildings are either framed with structural steel or reinforced concrete and walls are erected with bricks or cinder blocks usually with poor insulation standards. Construction work requires a wide variety of skilled trades. Each step has to be completed by certain workers before the next team could begin their job. Disposal of materials waste mostly made up of cement and gypsum seriously impacts the environment. Buildings framed with reinforced concrete are generally heavier and consume large quantities of steel rebar in their foundations, floors, and columns.

[0004] Whether with wood or otherwise, each site-built home or building has to follow strict local and national codes and regulations which sometimes slow down the progress ofconstruction. Work usually cannot proceed to the next stage until a team or contractor has finished their job or until an inspection is done and an approval or permit is obtained. Unforeseen circumstances such as a supply shortage and delay in the procurement of a single material could have a chain reaction and put the entire project on hold, leading to a delay in project completion date. Delays are almost inevitable in such environments as things do not always go as planned. With lower productivity and outputs, traditional onsite construction methods are less efficient and more labour- intensive than the alternatives.

[0005] Off-site construction methods such as panelized, prefabricated, or modular offer a better alternative. With slight differences, some apply and copy virtually the same construction methods and techniques and use the same materials as on-site. The majority of work is done inside a facility where workers are protected from outside whether elements and where working at heights is nearly eliminated. This leads to a safer work environment and comparatively higher productivity since most components and sections are precisely cut, glued, nailed or welded, laid out and arranged by machines and robots before final assembly. Automation makes the process smoother, faster and more efficient. Materials waste is fairly diminished this way. Modules or units come fully equipped with MEPs and interior walls and fixtures. They are shipped on trailers to the job site, lifted by cranes, fitted and fixed into place by a small installation crew. These methods require fewer skilled trades and workers compared to traditional on-site construction.

[0006] The intricacies and complexities of onsite construction creates a high demand for skilled labour and trades. Skilled trades shortage potentially hinders and impacts the production rate of new homes and buildings and consequently housing affordability. Supply has not be able to effectively keep up with the demand as fewer homes are being built annually. This has put affordable housing out of reach to many. However, with the help of technology and automation, off-site construction methods could help alleviate the demand for skilled trades and boost production. Streamlining manufacturing and production of repeatable and standardized panels, units, and modules leads to a faster and cheaper construction process than conventional on-site methods, which struggle to keep pace with the growing demand for more housing. The global market share of prefabricated housing is just under 5% largely due to skepticism and unfamiliarity with this industry. Shortage of affordable housing is a chronic issue which could be solved with the widespread adoption of new innovative off-site construction methods and techniques which enhance efficiency and productivity and help increase supply of new homes.Summary of the invention

[0007] The invention disclosed here is a building construction system and method for residential, commercial, and industrial construction. Panelized interior and exterior walls made up of cold- formed light gauge steel units (Figure 1) are prefabricated off-site. Exterior walls come finished with insulation, windows, weather-resistant barriers (WRB), sidings and claddings (Figure 2). Onsite, walls are lifted with a crane, placed on and attached to a slab foundation and to each other with rivets or screws. Floors are framed on-site with prefabricated floor joist units (Figure 3). Pre-cut oriented strand boards (OSB) are placed between joist units on bottom flanges, forming a flat platform along the length of joists for workers to walk and work on. Walls of the next level are craned in, placed directly on top of lower floor walls, and fastened to the joists below and to each other. MEPs are installed, running horizontally along and across floor joists through cutouts, and vertically along the wall cavities (Figure 4 & Figure 14). Lighting, plumbing, HVAC fixtures are installed into the floor and wall cavities. Pre-cut subfloor OSB or plywood boards are laid and fastened to joists. Finally gypsum boards or drywall panels are hung and fastened to walls and to OSBs above in the ceiling.

[0008] Light gauge steel plays an important roles in this system. It is versatile, durable, and lightweight and can be cut, shaped, and formed into any pattern or design with conventional laser-cutting and cold-forming machines. Streamlining procedures for fabrication of floor joists and walls, installation of insulation, weather-resistant barriers, windows, sidings and claddings helps all these tasks to be efficiently done by workers with basic training and skills in a facility protected from outside weather. OSB and plywood boards are precisely cut with CNC machine, sorted, stacked, and bundled according to each floor plan and layout with minimal discard. Transporting wall panels, floor joists, and wood boards on a trailer to the job site is convenient. Onsite installation of walls, floor joists, pre-cut OSB and plywood boards can all be done by supervised workers with basic training and skills.

[0009] A unique feature of this method is the way MEPs can conveniently be installed through floors and walls. They run vertically up or down unobstructed in spaces between studs along walls of multiple floors and horizontally along and across floor joists. Unlike traditional methods, MEPs are installed into the roof cavity between floor joists from above, from the next level's floor where workers can conveniently bring, move, run, access, and work on them. The OSBs sitting at the bottom between joists have been designed for this purpose and for providing a platform onwhich MEPs can permanently rest without requiring overhead hangers, trapeze support brackets, and suspended cable trays. This eliminates strenuous and time-consuming tasks of installing MEP components into or under ceilings from below as well as the need for complex and complicated prefabricated mechanical racks and modular MEP systems in commercial projects.

[0010] Another unique feature of this system is the wall design. Unlike a traditional wood or light gauge steel stud wall where individual studs are arranged and spaced specified distances apart, the wall here is a continuous pattern of alternating square and hexagonal light gauge steel studs. Compared to conventional wood or steel studs, resistance to buckling is significantly enhanced due to having a set of twin studs facing each other forming a square or hexagon, and mainly due to having a continuous and rigid bracing from top to bottom of studs. Floor joists, either parallel or perpendicular to the wall, are fastened to the square studs. All exterior and interior walls are load-bearing with an in-wall girder beam spanning the entire length of the wall for floor joists to directly sit on. Walls are connected to each other simply with rivets or screws to form a rectangular or square grid or lattice (Figure 5). Any floor plan or layout can be constructed this way. The need for structural OSB or plywood sheathing is eliminated since this design is fully capable of withstanding both vertical and lateral loads. This makes the structure relatively stronger than conventional concrete frame, wood frame, and light gauge steel frame (LGSF) buildings against earthquakes and hurricanes; and more fire-resistant.

[0011] This building system and method could primarily be used and applied in low-rise multifamily residential construction with standardized repeatable floor plans and layouts. It could also be widely used in commercial and industrial construction projects such as healthcare facilities, hotels, office buildings, schools, retail stores and strip malls, warehouses, manufacturing plants, and workshops. With pre-specified and pre-approved elements such as materials, MEP and safety systems complying with national and local building codes and regulations, buildings of various sizes and capacities with a wide variety of interior and exterior facade options could be constructed and ready for occupation at a fast pace which would lead to a steady increase in the supply of affordable housing as well as affordable commercial spaces.

[0012] Employing engineers, builders, technicians, and architects in planning and designing homes and buildings based on this system, training average workers to work both off-site on the production and on-site on the assembly and installation, and benefiting from skilled trades andcraftsmen during finishing stages are some of the core features of this technology whereby a traditional complex and taxing process is simplified, streamlined, and executed more efficiently.Brief Description of Drawings

[0013] Figure 1 illustrates the wall unit of this invention which features a square and a hexagonal stud made of cold-formed light gauge steel (LGS) with reference numbers identifying its components.

[0014] Figure 2a illustrates the interior side of a typical exterior wall panel prefabricated with wall units and finished with insulation and weather barriers. Drywall panels are installed on-site.

[0015] Figure 2b illustrates the exterior side of same wall as in Fig. 2a with window header installed on top.

[0016] Figure 3 illustrates the prefabricated cold-formed light gauge steel (LGS) floor joist unit of this invention.

[0017] Figure 4 illustrates the floor system of this invention fabricated on-site with reference numbers identifying its components.

[0018] Figure 5 illustrates the wall-to-wall connection layout.

[0019] Figure 6 shows floor joist units enclosing and attached to square studs. It also shows a header installed on top of window openings.

[0020] Figure 7 and figure 8 show walls, insulation, window headers, gypsum boards, and joists.

[0021] Figure 9 and figure 10 illustrate a typical light gauge steel staircase and elevator shaft system built with this invention.

[0022] Figure 11 illustrates a prefabricated common wall with support brackets installed under floor or roof joist.

[0023] Figure 12 and figure 13 illustrate a typical 2-unit building built with this system.

[0024] Figure 14 shows a cutaway view of plumbing installed through floor and walls.

[0025] Figure 15, figure 16, figure 17, and figure 18 illustrate an embodiment of this invention which is a multi-unit multi-story building with a flat roof.

[0026] Figure 19 illustrates a typical cold-formed heavy gauge steel support system for long-span structures or buildings built according to this system and method.Detailed Description of the Invention

[0027] Referring to Figure 1, a light gauge steel (LGS) wall unit and system (4) is presented. It is made out of thin sheets of galvanized steel cut and cold-formed into symmetrical patterns (4a) and (4b). Square and hexagonal-shaped studs are formed by fixing the two sheets together with rivets, with a girder (5) and a flat strapping (3) spanning the entire length of the wall panel sandwiched between them. A pair of clip angles (6) are riveted or screwed to the sides of the hexagonal studs acting as stiffeners. Wall units (4) are riveted or screwed together to form a wall panel. A track (1) spanning the entire length of the wall panel having cutouts (2) at specified intervals for running MEPs through, is riveted to wall units.

[0028] Girder (5) made of a thicker steel sheet (lower gauge) than the wall unit (4) at about 2-2.5 mm (1 / 10 in) in thickness is designed to support and distribute the load evenly among studs. The flat strapping (3) same thickness as girder (5) and same height as the track's walls (1) about 3 cm (1.2 in) is designed mainly to hold the units together before track (1) is installed and to help distribute the load evenly along (1). Wall unit (4) has a length spanning about 80-90 cm (32-36 in) with a space about 20-22 cm (8-9 in) between square and hexagonal studs where cutouts (2) are situated. The width of the wall unit is designed so as to accommodate a cavity about 11-13 cm (4-5 in) deep for MEPs like PVC pipes to fit and run vertically along studs. The thickness and gauge of the light steel used to manufacture (4a) and (4b) is a decisive factor in determining the load bearing capacity of the wall. The thicker it is, the greater its load-bearing capacity, and as a result the more material is used and the heavier it becomes. The wall height can be designed to suit the application for which it is intended. In residential construction, it is about 315-320 cm (10 ft 4in-10 ft 6in) to accommodate a final floor-to ceiling height of about 274 cm (9ft).

[0029] A wall panel fabricated from individual wall units (4) is shown in Figure 2. Insulation foam blocks (7) made of EPS or XPS are first inserted into the square and hexagonal studs before they are put together and later additional blocks are inserted into exterior wall cavities. The interior cavities are left unobstructed for MEPs. Interior walls are uninsulated. Fig. 2a shows the interior of a typical wall panel with gypsum boards or drywall panels (10) installed. Gypsum boards are actually not installed at the factory. They will be installed later on-site after MEPs are in place. Fig. 2b shows the exterior with insulation blocks (7) and weather-resistant barriers (9) installed. Breathable membranes that protect against moisture, air, and water infiltration are used in (9). Window openings are created with shorter height wall units installed at the bottom and top, and reinforced with header (8) to support the load applied from above by floor or roof joists.

[0030] A single joist resembling (11) spanning horizontally across window openings serves as the header (8). This continuous member effectively supports and distributes the load along the entire length of the wall. Windows are installed fully airtight and waterproofed. Siding and cladding materials are placed on top of (9) with or without furring strips and securely fastened onto wall studs. Header (8) creates an unwanted step or raised surface on the exterior of the wall panel. It can be filled with insulation foam blocks and covered with siding and claddings. Rough openings for doors and doorways are created by simply installing shorter height wall units only at the top. For average bedroom doors one unit is wide enough. For other applications and designs two or more units would do the job. They are installed on and held together by girder (5).

[0031] Floor joists are made out of galvanized light gauge steel cut and cold-formed. As shown in Figure 3, a floor joist unit (24) is composed of a pair of joists (11) attached together back-to-back by a set of light gauge steel blocking members (12) spaced at specified distances apart. The gap between the pair is exactly the same size as the square studs. Cutouts (13) are designed for MEPs. All units arrive at the construction site prefabricated ready to be craned into place.

[0032] Floors are framed on-site after walls are installed and secured. Figure 4 shows the design of a typical floor framed and built with this method. Floor joist units (24) are lifted and lowered into place, and temporarily fixed to the upper part of square studs with rivets or screws. Once in place, joists' top flanges are flush with top of walls as can be seen in Figure 6. There is no top track or plate designed for walls. Pre-cut OSBs (15) are placed between joist units on bottom flanges and screwed in place. From this point on, workers can walk and work on them. Securelyattaching joists to walls is conveniently completed at this stage. Walls of the next floor are lifted into place and tracks are securely fastened to the joists' top flanges with screws or rivets. Walls parallel to floor joists are secured down to the joists' top flanges with angle brackets. Since access to the back of exterior walls is very limited, extra brackets and connectors are installed from the inside.

[0033] MEPs installation is done at this stage inside the floor and wall cavities. Here workers have ease of access to all areas. Where needed, holes could be drilled through walls between studs to run MEPs. The gap between pair of joists as well as the cutouts and openings through joists allow workers to reach underneath when necessary. Next step, joists are glued and pre-cut subfloor OSB or plywood boards (16) are screwed down. In this system walls are designed to sit directly on top of each other with no top plates or tracks or boards in between. As a result, subfloor boards are not installed similar to wood-framed homes to cover the entire area. They only cover areas between walls and not under. Once final MEP fixtures are installed, gypsum boards or drywall panels (10) and (14) are hung and screwed to walls and OSBs respectively.

[0034] The configuration of walls and floors as well as windows and door openings are all shown from various angles in Figure 6, Figure 7, and Figure 8. A typical light gauge steel staircase and elevator shaft designed for this system is shown in Figure 9. The elevator shaft (17) is surrounded by a staircase. Stringers (19) installed and fixed onto the wall studs on either side. A rigid sheet cold-formed into stairs (treads and risers) (18) with a landing on top sits on and fixed to stringers. Next sets of stairs and landings follow same pattern.

[0035] A typical 2-unit building built with this system sharing a common wall (20) is shown in Figure 12 and Figure 13. Floor joists of each unit start from the opposite exterior walls, and end with resting and fixing onto the common wall. Figure 11 shows the common wall (20) with a set of support brackets pre-installed off-site on both sides of the wall for joists to sit on. Joists extend to only half of the common wall's width. The load on the common wall is greater than others, therefore it needs to be fabricated with a lower gauge steel. All dimensions remain same as other walls. Only thickness of (4) is increased. Each additional storey or level built on top of first floor has to have same layout and floor plan. Since all exterior and interior walls are load-bearing, walls sit only on walls and not on joists. However, Non load-bearing partition walls could be accommodated to be exempt from this rule in order to have a slight variation in each floor plans.

[0036] Figure 14 shows a cutaway view of plumbing through floor and walls. PVC drain pipes can start from foundation and extend vertically up uninterrupted all the way to the last floor and roof. At each floor a tee or a 4-way cross fitting can be used to connect other pipes to the main pipe. Pipes and most MEPs are run up or down passing through wall track cutouts (2). HVAC rigid or flexible ductwork not fitting through the wall cavity are installed right outside on the wall and covered. They would run to upper or lower floors passing through (14), (15), and (16) instead.

[0037] In residential, commercial, and industrial buildings built with this system with wide spans, support columns and beams could be used under joists to further reinforce and support the floors or the roof. A typical support system is shown in Figure 19 in which members are cold-formed heavy gauge steel. Columns (22) support horizontal beam (21) which spans perpendicular to floors joists. In multi-level buildings, columns are designed to be square with same dimensions as the square studs to fit through the gap in floor joist units (3). Beams are stiffened and reinforced at areas where columns sit (23) to prevent web buckling under compressive point and localized loads. Starting from the foundation and continuing up through floors, each floor would have its own columns resting on top of the beams below and fastened to the floor joists. The support system would be designed according to the load at each elevation, with first floor columns bearing the maximum and the last floor under the roof bearing the minimum.

[0038] Roofs in this system and method are flat and follow exactly same design and procedures as the floor system with OSB or plywood boards covering the entire roof area. Batts and rolls insulation could be inserted into the roof cavity before boards are installed on top. Overhangs and eaves can be created with extended joists.Preferred embodiment of the invention

[0039] An embodiment of this invention is illustrated in Figure 15 and Figure 16. A typical low- rise multi-unit building with a common wall and a flat roof built with this system is shown from different angles. The configuration of each floor and level is further shown in Figure 17 with more details in Figure 18. A staircase and elevator shaft system for this building is shown in Figure 10 with same components as in Figure 9.

Claims

ClaimsClaim 1: A building construction system comprising:- a set of wall panels prefabricated off-site with a set of light gauge steel wall units (4); and- a floor system designed to function both as a floor and as a flat roof, fabricated on-site with a set of prefabricated light gauge steel floor joist units (24).Claim 2: The system of claim 1, wherein the wall panel is composed of a number of wall units (4) attached together on a track (1) along the wall, a girder (5) on top, and a flat strapping (3) at the bottom both sandwiched between studs and spanning the entire length of the wall, the girder made of heavy gauge steel designed to evenly distribute the load among studs.Claim 3: The system of claim 2, wherein the wall unit is composed of a pair of symmetrical and continuous cold-formed light gauge steel studs (4a) and (4b) fastened and held together through the girder and the flat strapping to form a square-shaped and a hexagonal-shaped stud, the latter stiffened at the top by a pair of angle brackets.Claim 4: The system of claim 1, wherein the floor system is composed of a number of floor joist units (24) placed on girders and attached to the square studs on either side, a number of oriented strand boards OSBs (15) placed and attached onto bottom flanges between joist units, and a number of subfloor OSB or plywood boards (16) placed on and attached to the floor joists.Claim 5: The system of claim 4, wherein the floor joist unit is composed of a pair of symmetrical cold-formed joists (11) placed apart back-to-back and firmly attached together with a number of blockings (12) creating a gap between joists as wide as the square studs.Claim 6: The system of claim 3, wherein window openings in the wall panel are created with shorter height wall units installed on top and bottom and a modified single floor joist installed above as the header (8), and wherein door openings and doorways are created with a shorter height wall unit or units installed on top only.Claim 7: The system of claim 4, wherein the OSBs (15) are designed to provide a flat platform on which workers could conveniently walk and work and MEPs sit and be fastened to, and to which ceiling gypsum boards or drywall panels are screwed.

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