GB2608983A

GB2608983A - Modular building construction elements and methods

Info

Publication number: GB2608983A
Application number: GB2107219.4A
Authority: GB
Inventors: Jacobs Michael
Original assignee: Kiss House Ltd
Current assignee: Kiss House Ltd
Priority date: 2021-05-20
Filing date: 2021-05-20
Publication date: 2023-01-25
Also published as: GB202107219D0; EP4341502A1; WO2022243699A1

Abstract

The floor element, particularly for a modular building, comprises a generally planar orthogonal framework including at least two edge beams of composite material and a plurality of joists 113 projecting from at least one of the beams and accommodated in a cavity between upper deck boarding 120 and lower base boarding 121, the cavity sealed to restrict moisture ingress. The beams, joists and boarding may comprise the same composite material, preferably fibre (e.g., glass fibre) reinforced plastics. The boarding may be bonded to the beams by a continuous line of adhesive, optionally epoxy resin. The edge beams and joists may comprise C-sections or hollow rectangular or square sections, optionally two or more stacked together. The cavity and/or the hollow beams may contain insulation 145. There may be an upstanding tongue on one or more edge beams and/or support members on the upper boarding to support an upright panel in use.

Description

Modular building construction elements and method The present invention relates to the field of building construction, and in particular modular construction techniques in which portions of buildings are constructed off-site (i.e. in a manufacturing facility away from the place in which the building will be installed).

Conventionally, to build a volumetric modular house off-site, a structural ground floor element should first be constructed. Walls and a roof are built to create boxes that stack to make buildings. The ground floor boxes need to be craned onto foundations that have been prepared in advance at the location the house will be assembled. The standard solutions involve timber or steel/aluminium ground floor elements. In each case they need to be ventilated to prevent damp and harm from condensation. Thus, they are usually placed on concrete strip footings, pads, piles or suspended pre-cast concrete planks. The need to provide a level threshold to comply with building regulations adds further complexity requiring either ramps to front doors above ground level, or expensive sub-floor drainage strategies if the threshold is to be at ground level. This all adds cost and complexity and environmental impact.

The present invention seeks to overcome these issues by providing a building system which does not require sub-floor ventilation, has very low thermal conductivity and substantially matches steel for strength whilst being lighter.

Modular buildings that require bespoke and specific construction materials can be more expensive to produce. However, certain building requirements or sites on which buildings are to be constructed require tailored components for construction. The present invention also aims to provide several standard floor assemblies from which the most suitable floor assembly may be selected for each modular building according to variables such as budget, timeframe for construction, and ground type.

According to one aspect of the invention there is provided a floor element for a modular building comprising a generally planar orthogonal framework of beams, the framework being provided with a lower base boarding and an upper deck boarding which define a floor cavity therebetween, wherein the framework comprises at least two edge beams formed of a composite material, and a plurality of joists projecting from at least one of the edge beams, the joists being accommodated in the floor cavity, wherein the dimensions and shape of the edge beams and joists, the thickness of the lower base boarding and upper deck boarding are all selected according to the predetermined requirements of each modular building for which the floor element is provided and wherein the enclosed floor cavity of the floor element forms a sealed unit to substantially restrict ingress of moisture within the cavity.

The edge beams are in some embodiments formed of glass fibre reinforced plastic (GRP) which is widely and cheaply available but could be made of a bio-composite material comprising natural fibres in a resin matrix.

Plastics' or 'resin' material is intended to refer to a polymeric material, including co-polymers suitable for use as the matrix for reinforcing fibres. These may be thermoset polymers such as epoxy resins or thermoplastic, such as polyester. The composite material preferably comprises elongate fibres that are longitudinally aligned along the length of each beam or joist.

Optionally, the beams, lower base boarding, upper deck boarding and joists are formed from the same composite material. The beams, lower base boarding, upper deck boarding and joists may all be formed from fibre reinforced plastics material. The fibre reinforced plastic may be a glass fibre reinforced plastic.

Advantageously, use of GRP for forming the components of the floor element reduces environmental impact, weight, cost and improves thermal performance and production efficiency.

The base boarding and/or the upper deck boarding may be structurally bonded to the beams and/or joists. The bond between the beams and the joists may also act as a seal to create a sealed floor cavity and substantially restrict ingress of moisture. The base boarding and/or the upper deck boarding may be bonded to the beams and/or joists using an adhesive. A continuous line of adhesive may be disposed between the boarding and the beams/joists to form a seal to substantially restrict ingress of moisture to the floor cavity.

A structural adhesive may be provided to bond and seal the beams, joists and boarding. The structural adhesive may comprise an epoxy resin. Advantageously, epoxy resins have good mechanical and thermal properties, high water resistance, high temperature resistance and low cure shrinkage The act of adhesively bonding the beams, joists, upper and lower base boarding is advantageous since it forms a large composite structure with improved strength and load bearing capability.

The edge beams are optionally elongate hollow beams. The beams may be rectangular in cross-section.

Alternatively, the edge beams may comprise a C-shaped cross-section. The edge beams having a C-shaped cross-section may have a standard dimension. The C-shaped cross section beams may be a commercially available construction product. The C-shaped cross section beams may have a dimension of around 240mm between the outer faces of the two flanges of the C-shaped cross section.

Advantageously, use of C-shaped cross section beams having a standard depth enables use of readily available construction materials, that are arranged to form a floor element of the desired construction having the requisite strength to support a particular layout for a modular building.

Where C-shaped cross section edge beams have a depth of 240mm, spacing between transverse joists may be in the range 200 to 500mm. The spacing between transverse joists may be in the range between 300 and 475mm. Optionally, the spacing between adjacent joists is around 450mm.

Alternatively, the C-shaped cross section edge beams may have dimensions tailored according to a particular application. The C-section beams may have a dimension of around 300mm between the outer faces of the two flanges of the C-section.

Where C-shaped cross section edge beams have a depth of 300mm, the spacing between transverse joists may be in the range 150 to 350mm. The spacing between transverse joists may be in the range between 170 and 320mm. The spacing between adjacent joists may be around 300mm.

The floor element may be provided with lateral supports or stiffeners extending between adjacent joists. The lateral supports may be longitudinally aligned within the floor element. Ends of the lateral supports may be bolted to the abutting joists and/or edge beams. The lateral supports may be provided towards edges of the floor element. The lateral supports may be provided within the floor element to add strength and distribute load in a particular area of the floor element such that the area above the lateral supports can support a greater load, such as a load bearing wall.

The floor element is intended to be prefabricated and then transported flat-packed to a construction site for use in constructing a building. The use of a C-section or rectangular-section fibre reinforced plastics (FRP) edge beam and joist framework makes the structure lightweight (as compared to structures using conventional steel l-beams, or engineered wood beams).

This reduces transport costs and facilitates manipulation and placement of the floor elements at a construction site, saving time and labour. FRPs (typically glass-reinforced plastics) are good thermal insulators, and do not corrode. They therefore reduce dissipation of heat from a building and mean that ventilation requirements (to prevent condensation or damp) are less onerous.

The edge beams provide an impervious abutment for wall panels, such as structural insulated panels (SIPs), so that damp cannot seep into the building edges.

The floor cavity is preferably filled with an insulating filler material. Where hollow edge beams are used, the hollow edge beams may be filled with insulating filler material. The insulating filler material can comprise any known building insulation material, but to ensure longevity would not comprise natural fibres, but would rather be a synthetic material. This is because this filler will be close to the ground and thus may be exposed to damp or wet conditions. The filler preferably comprises mineral wool. This filler is preferably provided during the pre-fabrication process but could be provided by retro-filling of the floor cavity on site, such as via orifices formed in the upper boarding.

The joists could be any structural beam but should preferably have substantially planar upper and lower faces so as to provide support to the underlying base boarding and upper deck boarding. The joists could be I-beams, Z-beams or most preferably C-section beams. The joists are also preferably formed of FRP material (including biocompatible materials) of the types listed above for the edge beams and providing the same benefits.

The edge beams may be comprised of two or more juxtaposed sub-beams. In another aspect of the invention each primary edge beam comprises two vertically stacked rectangular-section beams. There may be two sets of vertically stacked rectangular-section beams arranged side by side (so four beams). The vertically stacked rectangular beams are preferably each square-section beams.

Two edge beams may be disposed in an L-plan configuration to provide a floor corner element, which could then have further floor elements placed alongside the distal edges away from the corner.

Two edge beams may be arranged in a parallel configuration with the joists 20 extending between the two edge beams. The framework ends free of edge beams can then be placed against further such elements to make an elongate floor assembly.

In another arrangement, the floor element may have three primary edge 25 beams arranged in a C-plan configuration with one edge beam disposed parallel to the joists and the two other edge beams arranged parallel to one another with the joists extending therebetween. Alternatively, the floor element may have two edge beams disposed parallel to the joists and one beam orthogonal to the joists.

At least two floor elements may be laid alongside one another and joined to form a floor assembly. At least one of the floor elements may be provided with base boarding and/or upper deck boarding that extends beyond the transverse joists enabling the adjacent floor elements to be juxtaposed with at least one continuous upper and/or lower boarding surface. Joins between adjacent floor elements may be sealed and cavities may be filled with insulation to ensure a continuous watertight floor assembly made from one or more floor elements.

In yet another arrangement there may be four primary edge beams which form a rectangular perimeter of the framework and joists extending between two parallel opposite beams. This is especially useful for constructing a single roomed building (or floor of a building).

Two or more spacer beams may be provided attached to an underside of the base boarding, which spacer beams raise and support the framework with respect to the ground or surface upon which the element is placed. This may be used in the fabrication or location, or at the building site, to facilitate elevation and transport of the elements by a forklift vehicle. These spacers are usually temporary and are therefore removable before installation of the floor element at a construction site.

In a further aspect of the invention one or more of the primary edge beams is provided with an upstanding tongue feature. The upstanding tongue feature is preferably elongate in the longitudinal direction of the beam, and in some cases may be continuous along the length of the edge beam. Cut-outs may optionally be provided as and when required. The tongue is preferably disposed along an outer edge of each edge beam. This then provides an L-section, inward facing seat for upstanding wall panels, such as SIPs.

The floor element may further comprise a support for supporting an upright panel in use, the support comprising one or more support members disposed on the upper deck boarding, wherein the support member(s) are shaped and arranged to support an upright panel in a substantially perpendicular position relative to a plane of the upper boarding.

The support member(s) may be disposed on an outward facing portion of the upper deck boarding. The support members may be selected to match the width of the upright panel which they are provided to support. The upright panels supported by the one or more support members may include structural insulated panels and walls of various materials and types.

Each panel support may comprise two support members in parallel relation arranged beneath the anticipated location of the upright panel. The supports may be located above a reinforced or load bearing portion of the floor element. The support members may be in arranged in a spaced configuration. Alternatively, the support members may be arranged in an abutting configuration.

The support may comprise a box section, such as a square or rectangular support section. Alternatively, the support may comprise an open trough. Each support member may comprise an elongate shaped component. The elongate components may be C-section, box section, square-section or L-section.

Two pairs of stacked support members may be provided. A lower pair of support members may provide a base from which to support an upper pair of support members. The upper pair of parallel support member may be arranged to support the upright panel. An intermediate wall feature may be inserted between the upper and lower pairs of support members. The Intermediate wall feature may include a cavity tray.

The supports/support members may comprise a composite material, such as 20 fibre reinforced plastics. The supports/support members may be made from glass fibre reinforced plastics. Any gaps between or within supports/support members may be provided with insulation filler material.

The supports/support members may be provided with fixing features to assist fixing of the upright panel in a substantially perpendicular position relative to a plane of the upper boarding in use. The fixing features may include apertures. The apertures may be provided to assist keying of mortar into the support. Alternatively, the apertures may be pilot holes adapted to receive fixings, such as screws.

The supports and support members are advantageous because they allow the floor element to receive different types of upright panel for wall construction of the modular building and therefore enable the floor element to be used in conjunction with upright panels for a variety of build purposes.

The base boarding optionally comprises a fibre-reinforced plastic board, which provides protection from fire, impact, vegetation and frost. The base boarding may comprise a composite material such as pultruded glass fibre reinforced plastic. The base boarding may have a thickness from around 5mm to 12mm.

The thickness of the base boarding (e.g. 5mm or 12 mm thick base boarding) is selected according to the application. The base boarding may comprise a stretched skin to provide composite reinforcement.

The upper deck boarding may comprise a composite material such as fibre reinforced plastic, in particular pultruded glass fibre reinforced plastic. The upper deck boarding may have a thickness of between around 8mm and 12mm. The thickness of the upper deck boarding (e.g. 8mm or 12 mm thick upper deck boarding) is selected according to the specific application. Floorboards, tiles or carpeting may then be laid on top of the upper deck boarding.

The joists are attached to an abutting edge beam by any suitable method but may conveniently be attached via [-section brackets or cleats and using bolts, screws and/or adhesive.

According to a further aspect of the invention, there is provided a floor assembly comprising two or more floor elements according to the first aspect of the invention, wherein the floor elements making up the floor assembly are appropriately aligned and the join between the floor elements is sealed to substantially restrict ingress of moisture.

The join between adjacent floor elements may comprise a length of boarding, optional insulation for insertion into the gap between the upper and lower boarding there between and a means for sealing the join. Dimensions of the floor elements, the upper boarding and base boarding may be preselected to encourage close juxtaposition of adjacent components and minimise gaps therebetween.

The join line between adjacent components and the floor elements may by sealed using strips of sealant, such as sealant tape. Optionally or additionally, the join line between adjacent floor elements may be sealed with adhesive.

Thus, the present invention provides a selection of floor elements and/or floor assemblies for modular housing that is affordable, thermally efficient, complaint with relevant regulations and easily constructable and that caters for a range of budgets and building sizes.

In yet a further aspect of the invention there is provided a method of modular building construction comprising: providing one or more pre-fabricated floor elements as hereinbefore described, disposing the floor element or elements to occupy a floor plan and providing and erecting a plurality of upstanding structural insulated panels (SIPs) on the floor elements to form walls of the building, and optionally providing one or more further said pre-fabricated floor elements on the SIPs to form a ceiling or further floor for the building, and/or thereafter providing a roof for the building.

The floor element or elements may be disposed on a ground surface in the absence of foundations such as concrete strip footings, pads, piles or suspended pre-cast concrete planks. Typically, for many surfaces, all that is required is levelling of the ground surface. Proper foundations can of course optionally be used when desired.

Any aspect, embodiment, or feature described in the specification or shown in 20 the drawings may be combined with any other aspect, feature or embodiment of the invention where appropriate.

Following is a description, by way of example only of one mode for putting the present invention into effect, with reference to the figures in which: Figure la is plan view of a floor element of the present invention; Figure lb is an end-on view of the floor element; Figure lc is a side elevation of the floor element; Figure ld is an opposite end view of the floor element; Figures 2a to 2d show details of features shown in figure 1; Figure 3 is cross-sectional end view of an edge region of the floor element in accordance with the invention integrated with a lower wall portion of a modular building made in accordance with a method of construction of the invention; Figures 4a and 4b are plan and perspective views of another embodiment of a floor element according to the invention; Figures 4c and 4d are perspective views of details E and F respectively from Figure 4b; Figures 4e and 4f are views of section A-A and B-B respectively taken from Figure 4a; Figures 4g and 4h are sectional views of detail C and D respectively from Figure 4e; Figures 5a and 5b are plan and perspective views of another embodiment of a floor element according to the invention; Figures Sc and 5d are perspective views of details E and F respectively from Figure 5b; Figures 5e and 5f are views of section A-A and B-B respectively taken from Figure 5a; Figures 6a and 6b are plan and perspective views of another embodiment of a floor element according to the invention; Figures 6c and 6d are perspective views of details E and F respectively from Figure 6b; Figures 6e and 6f are views of section A-A and B-B respectively taken from Figure 6a; Figures 6g and 6h are sectional views of detail C and D respectively from Figure 6e; Figure 7 is an exploded perspective view of the floor element of figures 4a to 4h; Figure 8 is a partially exploded perspective view of a floor assembly comprising two joined adjacent floor elements; Figures 9a to 9c are sequential perspective views of a floor assembly comprising three floor elements during different stages of construction; Figures 10a to 10e are partial perspective sequential views of a sealed join being formed between two adjacent floor elements; Figure 11 is a sectional view of a support attached to an upper surface of the floor element supporting an internal blockwork wall; Figure 12 is a sectional view of a support attached to an upper surface of the floor element supporting an internal timber wall; Figure 13 is a sectional view of a support attached to an upper surface of the floor element supporting a structural insulated panel; and Figure 14 is a sectional view of a support attached to an upper surface of the floor element supporting a load bearing timber frame with blockwork.

In figure la three primary edge beams 10, 11, 12 of glass fibre reinforced plastics (GRP) material are arranged in a C-plan layout. The central beam 10 has outer end regions that are provided with L-section brackets 16 which are used to connect the outer end regions to proximal ends of each outer edge beam 11,12.

Three equispaced apart C-section GRP joists 13, 14 and 15 are disposed projecting transversely from an inner face of the beam 10. A proximal end of each joist abuts the beam and is attached thereto by L-section brackets 18. These are of the same shape and size as the brackets 16. Each plate of the bracket is formed with a pair of bolt holes (see figure 2a, detail A, and figure 1b) by which to attach the beam to bracket and bracket to joist.

As shown in figure lc, each edge beam comprises two stacked box (square) section members 12, 12' stacked one top of the other and bonded (or otherwise fixed) together. The stacked central beams 10, 10' are also shown end-on in figure lc. Two spacer beams 23, 24 are shown attached to an underside of the floor element one 23 set back and parallel to the distal ends of the joists. The other 24 lies directly under the stacked beams 10 and 10'. These spacer beams are usually only temporary fixtures to allow forklift access to the underside of the element for transport. The spacers are removable before installation of the floor element in a building site.

A deck of GRP boarding 20 is visible end-on in figure lc. The underside of this boarding is attached to upper faces of the joists, by gluing. Base boarding 21 is similarly attached to lower faces of the joists. The base boarding 21 is formed of GRP. Between the upper and base boarding there is defined a cavity 22 (actually a plurality of cavities separated by joists and beams) visible in figure ld. The cavities 22 are filed with mineral wool, shown schematically as hexagonal mesh. The voids within each beam are also filed with the mineral wool.

In figure lb two upstanding tongues 25 are shown at outer end regions of the central upper beam 10. These serve as brackets for supporting upstanding SIPs (not shown in figure 1).

Turning now to figure 3 the floor element 30 is shown integrated into a building portion. A lower end region 31 of an upstanding engineered wood panel 32 abuts the tongue 25 and is fixed by a screw (as shown). 300mm extruded polystyrene (XPS) insulation 33 is attached to an outer region of the upstanding panel. Horizontal planks 34 are attached outside the insulation to provide an exterior facade. Above the deck boarding 20 there is a layer of XPS insulation 35 with a floor 26 on top.

The present inventors have developed a construction system comprising bonded box section edge beams. Certain of the beams have a vertical fixing plate (tongue 25) to accommodate timber wall panels. The hollow box sections have the required mechanical stiffness yet are lighter than steel.

They may be filled with mineral wool for exceptional thermal performance.

The spanning C-section glass fibre joists provide a lightweight, thermally efficient system that can be founded directly onto well compacted hardcore or micro-piles. Barely any excavation, no concrete or steel is required, and there is no requirement for additional sub-floor ventilation. This will radically alter the cost profile of building construction.

Hollow square section edge beams, as shown in the embodiments described in figures 1-3, facilitate the construction of a cost-effective floor element as such beams are readily available. However, such commercially available beams have a comparatively short spanning section. Therefore, the above-described embodiment is particularly suitable for floor elements requiring shorter spans.

Three alternative floor element layouts 130, 230, 330 are described below, enabling tailored selection of the required floor layout according to the customer requirements. The following floor elements 130, 230, 330 have deeper profiles and are suitable for longer spans.

Three additional embodiments comprising C-section edge beams and transverse joists are described with reference to figures 4a-4h, 5a-5f and 6a-6h. To avoid repetition, like components have been given the same two-digit reference numeral, with the final two digits preceded by a third digit '1', '2' or '3'. These components are structurally similar and/or have a similar function unless otherwise described.

According to the embodiments of figures 4, 5 and 6, three GRP edge beams are arranged perpendicular to one another in a C-plan layout and each edge beam comprises a C-shaped cross section. The edge beams in each of the following embodiments are joined at mitred corners 141, 241, 341 using cleats bolted to inner ends of the edge beams. A plurality of transverse GRP joists 113, 213, 313 are equispaced and arranged parallel to the central edge beam 110, 210, 310. Ends of each transverse joist 113, 213, 313 are attached by L-section brackets or cleats 218, 318 to the parallel edge beams 111, 112, 211, 212, 311, 312 using bolts. Free ends 144, 244, 344 of the edge beams that are not attached to another edge beam are straight cut and extend outwardly relative to the outermost transverse joist 113, 213, 313.

Figures 4a to 4h and Figure 7 show C-section edge beams 110, 111, 112 and transverse joists 113 having a depth of 240mm. This size of C-section beams is an 'off the shelf' product thereby reducing the production cost of the floor element. The transverse joists 113 are parallel and spaced 450mm from one another. As best shown in the exploded view, there is a 12mm thick top layer of GRP boarding 120 bonded to the upper face of flanges of the edge beams 110, 111, 112 and joists 113. The underside of the upper boarding 120 is bonded to the flanges of the beams 110, 111, 112 and joists 113 with a continuous bead of structural epoxy resin adhesive. The primary function of the upper boarding 120 is to minimise vibration and improve sound deadening.

Base boarding 121 is structurally bonded to an underside of the lower flanges of the C-section joists 113 and C-section edge beams 110, 111, 112 to create a rigid structural composite. The base boarding 121 is 5mm thick GRP panel and creates a structure having enhanced stiffness by creating a reinforced composite structure. The floor cavity is filled with mineral wool insulation 145.

The selected dimensions of the beams, 110, 111, 112 joists 113 and boarding 120, 121 allow the floor element 130 of figures 4 and 7 to support load bearing weight at any point. Therefore, the resulting floor element 130 provides flexibility with regard to the remaining modular house design because there is no restriction on the placement of load bearing walls. Further, walls may be moved or relocated at a later date because the construction of the floor element 130 is not limiting in this regard. This embodiment is cost effective due to the use of standard readily available components incorporating flexibility for the placement of load bearing walls. However, additional groundwork may be required for support of this floor element 130.

The embodiment described in Figures 5a to 5f show C-section primary edge beams 210, 211, 212 and C-section transverse joists 213 having a depth of 240mm. The transverse joists 213 are parallel and spaced apart by a length of 450mm. An 8mm thick top layer of GRP boarding 220 is bonded in the manner previously described to the upper face of flanges of the edge beams 210, 211, 212 and joists 213. Use of these standard 'off the shelf' components result in a cost-effective floor element 230. However, the floor element 230 lacks the required support and structural strength for load bearing walls to span the full width of the modular building and therefore additional supports are required.

Lateral supports in the form of GRP stiffeners 246 are provided with straight cut ends that attach via cleats and bolts to the transverse joists 213 in the required location. The stiffeners 246 are aligned and fitted towards outer edges of the floor element 230 in predetermined locations to support the weight of load bearing walls (not shown) erected above the floor element 230 during construction.

The embodiment of figures 5a -5f provides the most cost effective floor element 230 but offers less flexibility on the placement or subsequent rearrangement of load bearing walls, with groundwork required for supporting joists.

A further embodiment is shown in figures 6a to 6h. This is a bespoke product with components specifically manufactured to construct the floor element 330, thereby increasing the cost. However, the selected dimensions of the various components enable the full weight of the modular building to be supported.

Figures 6a to 6h show C-section primary edge beams 310, 311, 312 and C-section transverse joists 313 specifically manufactured with a depth of 300mm. The transverse joists 313 are spaced 300mm from one another with a 12mm thick top layer of GRP boarding 320 bonded to the upper surface of flanges of the edge beams 310, 311, 312 and joists 313. The base boarding 321 is 12mm thick GRP panel and together with the C-section beams and joists creates a floor element having enhanced stiffness by creating a reinforced composite structure. In common with the previous embodiments the floor cavity is stuffed with thermal mineral wool insulation prior to bonding the upper boarding 220.

The floor element of figures 6a to 6h can support load bearing weight at any point along the structure and therefore provides flexibility in the placement of load bearing walls. While the floor element is more expensive than those previously described, it provides greater flexibility and does not require additional groundwork supports.

Thus, the ground floor elements 30, 130, 230, 330 support vertical loads (not shown) in the form of walls of the modular building using GRP panels and beams to minimise moisture and the consequent risk of corrosion and/or degradation of the floor element. GRP beams and joists provide the main floor supporting members spanning across the ground floor with intermediate foundation. Use of GRP reduces the need for insulation compared to steel cassettes.

The embodiments shown in Figures 4 to 6 show how the modular floor element may be provided with different standards (based on dimensions of the key components comprising the floor element) that are selected according to the requirements of a purchaser or developer. The three standard formats minimise costs while enabling some choice and flexibility in the design of a modular building tailored according to the specific building requirements.

In each described embodiment the GRP decking and base boarding is bonded to the edge beams and joists to provide a sealed composite cassette formed in its entirety from pultruded GRP members. The benefits associated with the described floor element 30, 130, 230, 330 embodiments are as follows.

-Reduced environmental impact as the resins and fibres used in GRP production have a lower environmental impact than the production of metals. -Improved thermal performance of the cassette by eliminating the cold bridging associated with metals.

-Improved production efficiency by use of similar materials throughout the cassette enabling bonding of the decking and base boarding to the structural members to create a composite panel with improved stiffness.

- Avoidance of coating processes associated with steels when used at ground level.

- The floor element is inherently waterproof potentially removing the need for a damp proof membrane (DPM) between the cassette and the ground.

- Reduced weight of components and final floor element.

Floor elements 130 may be joined together as shown in figure 8 and sequentially in Figures 9a-9c and 10a-10f. Three floor elements 130 are aligned and laid in adjacent relation (Figure 9a) such that the base boarding of adjacent floor elements 130 is in abutment. Floor elements 130 positioned alongside one another have internal surfaces that form an open cavity 50 (approximately 250mm wide) with the bottom surface formed from GRP base boarding 121 (Figures 9b, 10a). Sealing tape 51 is then applied to all joint lines within the cavity 50 (Figure 10b). The joins are sealed with a 100mm wide self-amalgamating, non-vulcanising joining tape 51 such as roofing 'flashing' tape (Butyband/Soudal). A GRP cleat 56 is fixed between GRP joists to fix floor elements together and avoid separation over time (Figure 10c). The cleat 56 is inserted over the tape 51 (Figure 10d). A strip of mineral wool 55 insulation is inserted into the cavity 50 (Figure 10e). A top strip of GRP boarding 52 of the required dimensions is mechanically fastened to seal the cavity 50. The strip of GRP boarding 52 is held in position by stainless steel self-tapping fixings. The join is finished with tape 58 across the gaps and over the fixings (Figure 10f). The tape 58 is 60 mm wide and may be DuPont AirGuard air and vapour control layer tape or the like.

The joined floor elements form a floor assembly 54 with the required dimensions and moisture resistance. External faces of the floor assembly 54 present a smooth GRP surface as the point of contact for external materials. Any of the other described floor elements 30, 230, 330 may be joined to form a floor assembly in a similar manner.

The bonded GRP ground floor element 130, 230, 330 comprising C-section beams and joists bonded to upper and lower layers of GRP sheets forms a stressed skin rigid component with inherent strength and water resistance. A composite cassette is achieved by the shear bond provided by the adhesive resin between the GRP joists and boarding. As a result of this composite action the floor assembly is able to support significant loading and reduces vibrations.

The floor elements 30, 130, 230, 330 may be supported by a conventional strip foundation. According to another embodiment the ground floor element 30, 130, 230, 330 is supported by screw piles such that corners of the panels and edge beams directly transfer load to the screw pile. Secondary horizontal beams along the intermediate screw pile location are used as a stiffener to ensure efficient load transfer and maintain adequate panel stiffness.

The remainder of the modular building may be constructed around the floor elements 30, 130, 230, 330 and/or floor assemblies 54 in the manner previously described with reference to figure 3.

Alternatively, or additionally, an upright panel support can be attached to the floor element(s) 130. Various embodiments of supports are shown in Figures 11 to 14, each supporting a different type of upright panel or wall.

Figure 11 shows a support for an internal blockwork wall 72. An external brickwork wall 71 is spaced from an internal blockwork wall 72 by a 100mm cavity 71. Plaster dabs 73 are provided at spaced intervals along on side of the blockwork wall 72. The plaster dabs 73support plasterboard for the internal facing portion of the wall. A cavity tray 74 has a lip that extends over a side edge of an 8mm Cembrit or similar kicker board 76 and the cavity tray 74 rests on an upper surface of the deck boarding beneath a cavity wall weep vent 75.

The base of the panel member in the form of the internal blockwork wall 72 is supported by two GRP L-section support members 80 that are bonded to an upper surface of the upper deck boarding of the floor element. Pre-drilled holes allow positive mortar engagement. The location of the support members 80 is selected such that the blockwork wall 72 stand above a structurally stiffened area of the floor element.

Thus, the floor element shown in Figure 11 is supplied with a support comprising two support members 80 bonded to the decking board to allow easy installation of a traditional masonry cavity wall in a location that has sufficient strength to bear the load. The support members 80 ensure that the inner blockwork wall 72 is correctly positioned over internal stiffeners or a load bearing portion of the floor element.

Figure 12 shows a support for an internal timber frame. An external brickwork wall 70 is spaced from an internal timber frame by a 120mm cavity 71. An outer face of the internal timber frame is provided with a breather membrane 77 behind which an 18mm OSB3 timber frame sheeting board 78 is supported from below. An internal face of the timber wall comprises plasterboard 79 with 100mm of mineral wool insulation 82 therebetween.

The internal timber wall comprises a timber frame base member 81, which is supported by two GRP L-section support members 83 that are bonded to an upper surface of the upper deck boarding of the floor element. Eke-drilled holes through side flanges of the L-section support members 83 assist the fixing of screws to engage with the base member 81.

Thus, the floor element shown in Figure 12 is supplied with a support comprising two support members 83 to allow easy installation of a hybrid brickwork and timber frame house. The support members 83 are preinstalled during fabrication of the floor element.

Figure 13 shows a support for a standard insulating panel (SIP) 85. An indicative external cladding is shown at 84 and a breather membrane 77 is placed between this and the SIP 85. An internal face comprises plasterboard connected to a plurality of battens 86.

The SIP 85 is supported by two GRP square-section support members 87 that are bonded using adhesive, such as an epoxy resin, to an upper surface of the upper deck boarding of the floor element. These support members 87 are spaced such that their outer faces match the width of the SIP 85.

Compressible mineral wool 88 is provided to fill the space between the support members 87. Pilot holes are provided through the side of the square-section support members 87. The pilot holes assist the fixing of screws to engage with the SIP 85.

Thus, the floor element shown in Figure 13 is supplied with a preinstalled support comprising two support members 87 to allow easy installation of a SIP 85.

Figure 14 shows a support for a cavity masonry wall with timber or masonry inner leaf. An external brickwork wall 71 is spaced from a load bearing inner leaf timber frame 89 with boarding membranes or blockwork by a 100mm cavity 71. Plaster dabs 73 are provided at spaced intervals along one side of frame 89. The plaster dabs support plasterboard for the internal facing portion of the wall.

The frame 89 is supported by two pairs of GRP support members 90, 91. The lower pair of support members 91 are C-section GRP members that are arranged to face one another to form a lower rectangular section support that is selected to match the thickness of the inner frame 89. The support members 91 are bonded to an upper surface of the upper deck boarding of the floor element using adhesives and the internal boxed area is filled with mineral wool insulation. A cavity tray 74 has a lip that extends over a side edge of an 8mm Cembrit or similar kicker board 76 and the cavity tray 74 rests on an upper surface of the deck boarding beneath a cavity wall weep vent 75. An opposing end of the cavity tray 74 is incorporated into the support.

An upper end of the cavity tray 74 rests between the lower pair of support members 91 and the upper pair of support members 90. The upper support comprises two GRP L-section support members 90 having pre-drilled holes to allow positive mortar engagement.

Thus, the floor element shown in Figure 14 is supplied with a double support comprising two pairs of support members 90, 91 attached to the upper surface and incorporating a cavity tray 74 to enable easy installation of a cavity wall with timber or masonry inner leaf.

It should be noted that a plurality of supports and support members may be provided on a floor assembly where appropriate to support upright members in the predetermined positions.

Modifications and improvements can be made without departing from the scope of the invention. For example, beams, joists and floor panels may comprise another suitable alternative material with the required strength and resistance to degradation. Embodiments of the invention show three primary edge beams in a C-plan layout: other L-plan or parallel layouts can also be formed using two or more edge beams in a similar principle and joined to form different arrangements of floor assemblies. Precise dimensions and/or spacings discussed in relation to the embodiments may be altered, while retaining the required strength and primary function of the components.

Relative terms such as 'upper' or 'lower' are used to aid understanding and are not intended to be limiting.

Claims

Claims 1. A floor element for a modular building comprising a generally planar orthogonal framework of beams, the framework being provided with a lower base boarding and an upper deck boarding which define a floor cavity therebetween, wherein the framework comprises at least two edge beams formed of a composite material, and a plurality of joists projecting from at least one of the edge beams, the joists being accommodated in the floor cavity, wherein the dimensions and shape of the edge beams and joists, and the thickness of the lower base boarding and upper deck boarding are all selected according to the predetermined requirements of each modular building for which the floor element is provided and wherein the enclosed floor cavity of the floor element forms a sealed unit to substantially restrict ingress of moisture within the cavity.
2. A floor element as claimed in claim 1, wherein the beams, lower base boarding, upper deck boarding and joists are all formed from the same composite material.
3. A floor element as claimed in claim 1 or claim 2, wherein the beams, lower base boarding, upper deck boarding and joists are all formed from a fibre reinforced plastics material.
4. A floor element as claimed in any one of the preceding claims, wherein the base boarding and the upper deck boarding is structurally bonded to the beams and joists by a continuous line of adhesive disposed therebetween.
5. A floor element as claimed in any one of the preceding claims, wherein the boarding is bonded to the edge beams and joists by a structural adhesive comprising an epoxy resin, such that the floor element forms a large composite structure.
6. A floor element as claimed in any one of the preceding claims, wherein the edge beams and joists are C-section beams formed from a glass reinforced plastic material.
7. A floor element as claimed in any preceding claim, wherein the two edge beams are disposed in an L-plan configuration, or a parallel configuration with the joists extending between the edge beams.
8. A floor element as claimed in any one of claims 1 to 6, wherein there are three edge beams arranged in a C-plan configuration with one edge beam disposed parallel to the joists and the two other edge beams arranged parallel to one another with the joists extending therebetween, or with two edge beams disposed parallel to the joists and one beam orthogonal to the joists.
9. A floor element as claimed in any one of claims 1 to 6, wherein there are four primary edge beams which form a rectangular perimeter of the framework.
10. A floor element as claimed in any one of the preceding claims, wherein one or more of the primary edge beams is provided with an upstanding tongue feature wherein the upstanding tongue feature is continuous and elongate along a portion of the length of the edge beam.
11. A floor element as claimed in claim 10, wherein the tongue feature is continuous along the entire length of the beam and wherein the tongue is disposed along an outer edge of each edge beam.
12. A floor element as claimed in any preceding claim, wherein the floor cavity is filled with insulating filler material.
13. A floor element as claimed in any one of claims 1 to 5 or 7 to 11, wherein the edge beams are elongate hollow beams that have a rectangular section.
14. A floor element as claimed in claim 13, wherein the edge beams comprise two sets of vertically stacked rectangular or square section beams arranged side by side.
15. A floor element as claimed in claim 13 or claim 14, wherein each edge beam comprises two vertically stacked rectangular-section beams.
16. A floor element as claimed in any one of claims 13 to 15, wherein the hollow edge beams are filled with insulating filler material.
17. A floor element as claimed in any preceding claim, wherein the floor element is provided with a plurality of aligned lateral supports or stiffeners extending between adjacent joists.
18. A floor element as claimed in claim 17, wherein the lateral supports are provided to add strength and distribute load in a particular area of the floor element that is intended to support a load bearing wall.
19. A floor element as claimed in any one of the preceding claims, wherein the floor element further comprises a support for supporting an upright panel in use, the support comprising one or more support members disposed on the upper deck boarding, wherein the support member(s) are shaped and arranged to support an upright panel in a substantially perpendicular position relative to a plane of the upper boarding.
20. A floor element as claimed in any preceding claim, wherein each panel support comprises two support members in parallel relation arranged beneath the anticipated location of the upright panel and wherein the supports are located above a reinforced or load bearing portion of the floor element.
21. A floor element as claimed in any preceding claim, wherein the support is provided with fixing features to assist fixing of the upright panel in a substantially perpendicular position relative to a plane of the upper boarding in use.
22. A floor assembly comprising at least two floor elements as claimed in any of the preceding claims, wherein the floor elements are laid in adjacent relation such that the primary edge beams are located on outward facing edges of the floor assembly.
23. A floor assembly as claimed in claim 22, wherein the base boarding and the upper deck boarding extends between floor elements to form a continuous upper and lower boarding surface.
24. A floor assembly as claimed in any of claims 20 to 23, wherein the at least two floor elements are sealed to substantially restrict liquid ingress and wherein cavities between adjacent floor elements are filled with insulating material.
25. A method of modular building construction comprising: providing one or more prefabricated floor elements or floor assemblies according to any one of the preceding claims, disposing the floor element or assembly to occupy a floor plan and providing and erecting a plurality of upstanding structural insulated panels (SIPs) on the floor element or assembly to form walls of the building, and optionally providing one or more further said pre-fabricated floor elements on the SIPs to form a ceiling or further floor for the building, and/or thereafter providing a roof for the building.
26. A method as claimed in claim 25, wherein the floor element or assembly is disposed on a ground surface in the absence of foundations such as concrete strip footings, pads, piles or suspended pre-cast concrete planks.