Glass fibre framed house construction

Abstract

A construction method for domestic house building whereby a prefabricated house frame made from glass reinforced plastic is assembled at the start of the build, followed be a lightweight roof stru

Description

Current construction practices predominantly utilise timber and steel as primary framing materials. However, these materials have significant limitations, including susceptibility to rot, corrosion, and warping due to temperature and moisture changes. Additionally, steel can create thermal bridges, reducing energy efficiency. In contrast, the present invention utilises Glass Reinforced Plastic (GRP), which offers a lightweight alternative, eliminating the need for heavy lifting equipment on-site and an accelerated assembly time. GRP’s resistance to environmental factors, and non-thermal bridging properties enhance the overall efficiency and durability of the building structure. Summary The invention involves a single storey house frame constructed from glass reinforced plastic (GRP) sections that are prefabricated off-site and supplied in kit form. The kit will allow easy and rapid assembly on-site, forming the skeletal structure of the building. The GRP frame supports a lightweight roof structure during the initial stages of construction, which provides shelter for builders, allowing for uninterrupted work during inclement weather. A dense block inner core is constructed within the GRP frame, followed by insulation. The dense block inner core is connected to the GRP frame using specially designed connector ties to create a composite structure. This arrangement prevents thermal bridging, while the dense block provides the core strength and thermal mass necessary for efficient home performance. The outer surface of the GRP frame acts as a substrate for the exterior materials of the building. The finished building will be draft fee and well insulated with a high level of thermal mass internally to provide an extremely efficient and comfortable living space. Detailed Description The Glass Fibre Framed House Construction features: • Low Embodied Energy: The use of GRP significantly reduces the environmental impact compared to traditional materials. • Non-Thermal Bridging: GRP is a low thermal conductor material, helping to separate exterior and interior temperatures. The GRP frame is connected to the inner core of the building through specially designed connector ties that further prevent thermal bridging. • Lightweight Construction: The low weight of the GRP frame sections facilitates easier handling and assembly, eliminating the need for heavy lifting machinery on-site. • Rapid Assembly: Prefabricated GRP sections allow for quick construction, crucial in regions with variable weather, such as the UK. • Unique frame tie system: a specially designed connection system between the GRP frame and the dense block inner core that requires no additional fixings and prevents moisture transmission and thermal bridging. • Resistance to Corrosion and Rot: GRP is impervious to common issues that affect timber and steel structures. • Temperature Stability: GRP maintains structural integrity without warping due to moisture or temperature changes. • Long lifespan: The enclosed nature of the GRP frame, with no exposure to sunlight or water, vastly increase the anticipated lifespan of this already highly resistant material. • Fire Resistance: The material's fire-resistant properties enhance safety. • High strength structure: The separate layers of the building combine to create a high strength composite construction. The construction process involves assembling the GRP frame and roof at the beginning of the build, which provides immediate shelter for subsequent work. An inner core of dense block material is built within the GRP frame, providing structural strength and thermal mass. This dense block core is connected to the GRP frame by a unique connection system, establishing a thermal barrier between the interior and exterior of the building. Insulation is installed between the dense block and GRP frame to create a completely insulated inner core. The GRP frame is prefabricated off-site to the exact specifications of the build, requiring much less energy to process than steel, and ensuring waste is kept to an absolute minimum. The material itself has very low embodied energy, and excellent thermal properties, offering an environmentally friendly alternative to traditional building methods with substantial benefits to the end user. In its initial form, the GRP frame has sufficient load bearing capacity and deflection resistance to support the roof structure, and workmen on the roof during construction. A high level of additional strength and rigidity is obtained later on through its connection to the dense block inner core. By completely isolating the dense block core of the building from exterior temperatures the thermal mass of the building is able to work as a storage heater, retaining warmth during cooler periods, thus reducing, or even eliminating the need for interior space heating. The opposite is also true in hot weather, where unwanted heat can be absorbed by the thermal mass, rather than being reflected back upon the occupants. Finally, the exterior upright sections of the frame provide a substrate for outer surface cladding materials. This outer surface of the building creates a weather barrier, protecting the frame from deterioration. An example of the invention will now be described, with reference to the accompanying sectional drawings, in which: Figure 1 shows the assembled GRP frame in position on a concrete slab. Figure 2 shows purlins connected to the GRP frame in order to accept the roof structure. Figure 3 shows the roof structure in position on top of the purlins. Figure 4 shows the dense block inner core structure and its connection to the GRP frame. Figure 5 shows the insulation located between the GRP frame and the inner dense block core. Figure 6 shows the completed structure. Figure 7 shows the unique frame ties that connect the GRP frame to the dense block core. Figure 8 shows the operational system for the frame ties. Figures 1-6 represent cut through sections of the construction concept, and do not depict a complete structure. In Figure 1 the GRP frame sections(l) have been cut and machined off-site and delivered in kit form on-site. The GRP frame sections(l) are assembled on top of a reinforced concrete base slab(5). The upright GRP frame sections are secured to the reinforced concrete base slab(5) using stainless steel bolts and brackets(4), and are braced where necessary with cross sections(2), and temporary diagonal braces(3). Where windows and doors are required(lO), additional GRP frame sections(l) would be added to form bearing surfaces for the required openings. The associated window or door frames would be fixed directly to the GRP frame(l). The upright GRP frame sections have a number of specially designed frame ties(9) placed at the top of each section. These ties are designed to remain in position until needed. The number of frame ties(9) for each section is calculated prior to assembly in order to provide a connection at every second course of dense block(Fig.4 / point 13). Details of the frame tie design are shown in Figures 7 and 8. Above the reinforced concrete base slab(5) is a waterproof membrane(6), followed by 300mm of polyisocyanurate (PIR) high density insulation(7), followed by 200mm of reinforced concrete slab(8). This top layer of concrete(8) creates the floor surface of the building, and provides some of the thermal mass required for the inner core. The base slab(5), waterproof membrane(6), insulation layer(7) and the floor slab(8) are installed at the start of the build. This ensures an unobstructed area for shuttering the concrete to form the required dimensions and location of the slabs. In Figure 2 purlins(ll) have been laid across the upper sections of the GRP frame(l), perpendicular to the frame sections that they are attached to. These purlins(ll) will establish the supporting layer for the roof structure, and can be made from GRP, or readily available lightweight steel if required, as they are protected from thermal bridging due to their location within the building structure. Figure 3 shows the roof(12) installed over the purlins(ll). The roof is constructed from lightweight insulated roofing panels, weighing 9kg per square metre. These are supplied in Imetre wide lengths that are pre-cut to the dimensions of the roof space, allowing for easily and rapid assembly. These roof panels are manufactured by a number of different companies, and are readily available. The roof panels(12) are completely waterproof and contain an integrated vapour control layer which avoids the need for additional damp proofing at this stage of the build. In Figure 4 the dense block core(13) has been constructed internally of the GRP frame(l), and the temporary diagonal braces (Fig. 1 / point 3) have been removed. The dense block core(13) is built on top of the upper concrete floor slab(8), connecting the thermal mass of both structures together. The internal dividing walls of the building are also constructed from the same dense block(13) material to maximise the building’s strength and thermal mass. The dense block core(13) is connected to the GRP frame(l) using the frame ties(9) shown earlier in Figure. 1. These frame ties are critical to the composite nature of the construction, ensuring the structural integrity of the building, and preventing temperature exchanges between the interior and exterior of the finished home. The ties(9) are brought down from their location shown in Figures 1, 2 and 3, and positioned between courses of the dense block(13) where they are trapped permanently in place, locking the GRP frame(l) and the inner dense block core(13) together. Any electrical wiring or ventilation conduit that needs to be located above the finished ceiling or behind the dense block(13) would be installed at this stage. In Figure 5 the exterior sides of the GRP frame(l) have been covered with a layer of marine grade plywood(15) and a waterproof membrane(6). This creates a waterproof barrier and a surface for insulation to be installed against. Closed cell expanded polystyrene (EPS) bead insulation(16) is installed between the plywood(14) and the dense block core(13), allowing the cavity to be filled tightly around the frame ties(Fig.4 / point 9) and GRP frame sections(l). The EPS beads are coated in an adhesive during installation so that once cured they form a single slab of insulation that adheres to the dense block(13), the marine grade plywood(15) and the GRPframe(l), creating a bonded composite structure. EPS bead insulation is fast to install, cost effective, long lasting and has excellent thermal properties. A layer of plasterboard(17) is installed to create a ceiling surface. Insulation(14) has been installed between the roof panels(12) and the plasterboard(17) creating a 300mm layer of insulation below the roofing panels. The roof panels(12) provide a further 70mm insulation, giving a total of 370mm of insulation. The inner core of the building - made up of the dense block wall structure(13) and the reinforced concrete floor slab(8) - is now completely encapsulated by insulation in the floor(7), wall(16) and roof(14). This protective cocoon of insulation allows the thermal mass of the building to function effectively, storing valuable heat during cooler periods, and absorbing unwanted heat during hot periods. Figure 6 shows the exterior cladding material(19) and the guttering(18) in place. The outer cladding(19) attaches to wooden battens that are fixed to the plywood layer(15) leaving an air gap between the cladding(19) and the plywood(15). The cladding(19) can be made from a variety of materials, providing a waterproof surface is achieved. The lower surface of the cladding(19) finishes above the ground surface to prevent moisture ingression. The waterproof membrane(6) covers the outer surface of the plywood(15), and blocks moisture ingress from below the ground level. Additional waterproofing would be installed in this area to further protect the plywood(15) layer. The guttering(18) connects directly to the rood ng panels(12) avoiding the need to bear weight upon the cladding surface(19). The guttering(18) is supplied by the roofing panel manufacturer, and is an existing component available on the market. Figure 7 shows the frame ties that have been designed to connect the frame and core of the building together. The connecting area(21) of the tie matches the profile of the GRP frame section(l) with a clearance of 0.25mm. A uniformly close fit between the frame ties and the GRP sections can be relied upon due to the accurate nature of the GRP sections which have a maximum variation tolerance of ±0.4mm. The ties(9) will be injection moulded in a 10 - 30% glass filled nylon, retaining some flexibility to allow for minor variations in the GRP section profiles, yet remaining stiff and strong enough to provide a secure connection to the dense block structure(13). Two ridges(20) are located along the body of the tie(9) to prevent moisture transmission. The ridges(20) create two lowered points where small droplets of moisture travelling along the surface would be blocked and dispersed. Once construction is complete there should be no possibility of moisture reaching these ties, but during the construction process, when the areas of the GRP frame are exposed, this barrier will prevent moisture from being transferred to the inner structure of the building. The ridges(20) intersect the body of the tie(9) providing additional strength along the length of the tie(9) where a gap would otherwise exist. At the tail end of the tie(9) is a loop(23) that will be encased in mortar and trapped between courses of dense block(13) creating an anchor point, and permanently connecting the dense block(13) and the GRPframe(l) together. The symmetrical design of the tie, with its snug fitting connection(21) around the GRP frame section(l), ensures the GRP frame sections(l) remain perpendicular to the dense block(13) wall that they connect to. Surrounding the connecting area(21) of the tie is a braced section(22) that prevents the connecting area(21) from opening or distorting if force is applied to the frame(l) or the tie(9). This ensures a strong and reliable connection between the GRP frame(l) and the dense block core(13). In Figure 8 the process of installing the ties can be seen. The frame ties(9) require no additional fixings to connect to the GRP frame sections(l), and can be placed in precisely the required position with no additional parts required. This saves money and time during construction and avoids the possibility of misaligning or badly positioning the ties. There are no screw fixings needed to secure the ties(9) in place, thus avoiding the need to drill into the GRP frame(l). This has both structural and practical benefits, ensuring the physical integrity of the GRP frame sections(l) remain intact, and avoiding the need to operate a drill between the dense block structure(13) and the GRPframe(l) which would be both messy and awkward. Drilling into the GRP frame(l) would also require specialist drill bits, incurring further limitations. The head of the frame tie (shown as point 22 in Figure 7) slides over the GRP frame section(l) allowing the ties(9) to be positioned at any chosen point along the length of the GRP frame section(l). Before the GRP frame is assembled, a pre-calculated number of frame ties would be inserted onto the vertical GRP frame sections(l) in preparation for connecting to the dense block inner core(13). The main body of the tie(9) protrudes away from the GRP frame(l) causing the ties(9) to naturally rest at approximately a 5° angle(24). This angle prevents the ties(9) from slipping down the GRP frame(l), so that they can be stored at the top of each frame section(l) until required. During the construction of the dense block inner core(13) the frame ties are brought down the GRP frame sections(l) one at a time as required to provide a connection point between the GRP frame(l) and the dense block core(13). When needed, a tie(9) is tilted back to a 90° position(25) making it perpendicular to the GRP frame section(l) and allowing it to move freely along a vertical axis to its required location. The ties(9) are designed to be placed on top of a course of dense block(13), whereby the proceeding course of dense block and mortar will anchor the tie(9) in position. Each vertical section of GRP frame(l) requires one frame tie(9) for every two courses of dense block(13).

Claims

1. A construction process for single storey domestic buildings that combines a frame of lightweight glass reinforced plastic (GRP), a dense block inner core and insulation to form a composite structure containing the following elements:• A pre-fabricated GRP house frame supplied in kit form.• A roof structure that is connected to the GRP frame during the initiation of the build.• An inner core of dense block that is connected to the GRP frame.• A connection system between the dense block inner core and the GRP frame that is dimensionally specific to the GRP frame sections, preventing movement and thermal bridging, and requiring no additional fixings to secure in position.• A layer of gap filling insulation between the upright sections of the GRP frame and the dense block inner core that adheres to all connecting surfaces.