This application is the U.S. National Phase filing under 35 U.S.C. §371 of PCT/GB2010/000700, filed Apr. 7, 2010, which designated the United States and was published in English, which claims priority under 35 U.S.C. §119(a)-(d) to Great Britain Patent Application No. 0906278.7, filed Apr. 9, 2009, the content of which is incorporated herein by reference in its entirety.
The present invention relates to a building and to a method of constructing a building. In particular, but not exclusively, the invention relates to buildings such as houses, schools, offices, hospitals and similar buildings, and a method of constructing such buildings.
There are numerous problems associated with conventional construction methods. One problem is that with many construction methods it is very difficult to construct a building having a very high degree of thermal insulation. Often, thermal insulation is provided by inserting an insulating material into a cavity between the inner and outer leaves of a wall. This material may be incorporated during construction of the building, for example by inserting solid blocks of an insulating material into the cavity between the inner and outer walls as the walls are constructed. Alternatively, an insulating material for example in the form of expanding foam may be pumped into the cavity between the inner and outer walls, after the walls have been constructed.
Different methods may be employed for insulating the roof space: for example, a blanket of fibrous matting may be laid between the ceiling rafters within the roof space. However, these conventional insulation methods often result in gaps being left at various places around the building, for example around the eaves and beneath the floor space. These gaps allow thermal bridging and enable air to flow into and out of the building, thereby allowing heat to escape.
Another problem with many conventional construction methods is that the construction costs are very high. For example, for conventional houses with brick or stone walls deep trenches have to be dug and concrete foundations laid in order to support the weight of the walls. This is both time-consuming and expensive. Another problem with many conventional buildings is that they are constructed using methods that are very labour intensive, such as by laying bricks. This also increases the cost of construction.
A further problem is that methods relying on the construction of solid walls make inspection of the building during construction very difficult, as many of the structural components will be hidden during the building process. This makes it difficult to confirm that the building complies with building regulations and good building practices.
It is an object of the present invention to provide a building, and a method of constructing a building, that mitigates one or more of the aforesaid disadvantages.
According to the present invention there is provided a method of constructing a building comprising a plurality of walls, a roof and a floor, said method including erecting a plurality of truss elements to form a framework comprising at least two opposed wall structures, a roof structure and a floor structure, each said structure comprising a plurality of truss elements, and each truss element including at least two joists and a plurality of braces that maintain the joists in a parallel arrangement, each said truss element being arranged in said framework to provide an inner joist and an outer joist; attaching an inner covering layer and an outer covering layer to said framework, thereby forming an enclosed void between said inner and outer covering layers that extends substantially continuously through the floor structure, the roof structure and the opposed wall structures, and injecting an insulating material into said void to form an insulating layer between the inner and outer layers that extends substantially continuously through the floor structure, the roof structure and the opposed wall structures.
The method allows buildings to be constructed relatively easily and at little or no additional cost as compared to conventionally constructed buildings, but to a very high level of thermal insulation, for example to a U-value for roofs, floors and external walls of less than 0.15 W/m2K and possibly as low as 0.05 W/m2K. This greatly exceeds the levels of thermal insulation that can be achieved using conventional construction methods without incurring substantial additional cost. This very high level of insulation is achieved owing to the fact that the insulation layer extends substantially continuously and seamlessly around the entire periphery of the building (including the roof structure, the walls and the floor) and seals any gaps in the structure, thus avoiding thermal bridges and preventing air leakage.
The construction method is simple to implement, requiring only basic construction skills and reducing the need for expensive plant and equipment. This leads to benefits in terms of improved safety at the construction site. The construction method is also very suitable for the rapid construction of buildings in an emergency, for example following an earthquake or other disaster, when skilled labour and expensive construction equipment may be in short supply. In such a case, the buildings may be constructed from locally available materials or from pre-fabricated kits of parts.
The structure of the building is very light and strong, owing to the direct connection between the truss elements forming the walls, the floor and the roof. The building does not therefore require very deep or continuous foundations and it is able to resist strong external forces, for example from earthquakes, hurricanes and other causes.
Furthermore, buildings constructed using a method according to the invention have an open framework that can be easily inspected during construction, allowing surveyors and building inspectors to confirm that the buildings meet all relevant building standards and regulations.
Advantageously, at least some of the truss elements that form the floor structure, the roof structure and the opposed wall structures are interconnected end-to-end to form a substantially continuous framework that extends through the floor structure, the roof structure and at least one of the wall structures.
Preferably, the interconnected truss elements that form each substantially continuous framework are located in a common vertical plane.
Preferably, the inner joists of the interconnected truss elements are interconnected, and the outer joists of the interconnected truss elements are interconnected.
Preferably, the method includes erecting a plurality of truss elements to form at least one end wall structure and attaching an inner covering layer and an outer covering layer to the end wall structure to form an end wall void, said end wall void being connected to the void that extends through the floor structure, the roof structure and the opposed wall structures.
Advantageously, the inner and outer layers forming the void have a separation in the range 50-600 mm, preferably 200-450 mm. We have found that with currently available insulating materials this separation provides an optimum balance of insulation thickness against building cost.
Preferably, the framework is supported on discrete piles or foundation pads. This reduces the cost of construction by avoiding the need to excavate conventional foundations. As the structure of the building is very light but strong, simple piles or foundation pads have been found to provide adequate support.
A damp-proof membrane may be fitted beneath the floor structure. Advantageously, the damp-proof membrane extends at least partly up the walls of the building, preferably to a height of at least 150 mm above ground level. The membrane may be extended to a greater height if required, for flood protection. This provides a very high level of flood protection (particularly if the building is also fitted with water-tight doors and windows).
The insulating layer in the roof structure may be provided within a ceiling structure, for example below a loft space. Alternatively, the insulating layer in the roof structure may be provided within a sloping roof structure, above a loft space.
Advantageously, the method includes applying an external finishing layer to the outer covering layer of at least one of the walls and/or the roof structure. Preferably, the external finishing layer includes an insulating layer.
According to another aspect of the invention there is provided a building including a plurality of walls, a roof and a floor, a plurality of truss elements that form a framework comprising at least two opposed wall structures, a roof structure and a floor structure, each said structure comprising a plurality of truss elements, and each truss element including at least two joists and a plurality of braces that maintain the joists in a parallel arrangement, each said truss element being arranged in said framework to provide an inner joist and an outer joist; an inner covering layer and an outer covering layer attached to said framework and providing an enclosed void between said inner and outer covering layers that extends substantially continuously through the floor structure, the roof structure and the opposed wall structures, and an insulating material filling said void and forming an insulating layer between the inner and outer layers, wherein the insulating layer extends substantially continuously through the floor structure, the roof structure and the opposed wall structures.
Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
a-18t illustrate a series of consecutive steps in a method of constructing the house,
In some trusses (for example types T1-T4, T6 and T9-T10) the two joists 4 are of equal length and their ends are joined by a cross-strut 8. In other trusses (for example types T5, T7 and T8), one joist is slightly longer and includes a portion 4′ at one or both ends that extends beyond the end of the other joist. In types T7 and T8, a cross-strut 8 is provided adjacent each end of the joist to support the extended portion 4′.
In the construction method, large numbers of trusses of various types are used. These trusses are preferably made to a standard specification, with a constant separation between the internal faces of the joists. For example, the individual joists may each have dimensions of 75×47 mm and be set at a separation between their internal faces of 206 mm, thus providing a width of 300 mm between the external faces of the joists. Other dimensions are of course possible, although generally it is preferred that the width between the external faces of the joists should be in the range 50-600 mm, preferably 200-450 mm. The length of each truss may vary according to the type of the truss and the intended location of the truss in the building. Typically the length may be up to about 10 meters.
In constructing a building, the types and number of trusses required to construct the framework of the building is calculated and the trusses are then fabricated and labelled. Normally, the trusses will be pre-fabricated off-site and labelled prior to delivery to the building site. Alternatively, they may be fabricated on-site. These trusses are then assembled in a predetermined order during construction of the building.
The layout of the trusses and other elements used in the construction of a simple two storey house is illustrated in
In this example, the framework of the ground floor 10 is constructed from fourteen trusses 2 of type T7, each having a shorter upper joist and a longer lower joist. These trusses are arranged parallel to one another, as illustrated in
The framework of the upper floor 12 is constructed from eight trusses of type T9 and five trusses of type T10, each having upper and lower joists of equal length. As illustrated in
The framework of the ceiling structure 20 is constructed from fourteen trusses of type T8, each having a longer upper joist and a shorter lower joist. As illustrated in
The framework of the front wall 22 is constructed from trusses of types T1, T2, T3, T4 and T6, as shown in
The right and left side walls 36,38 shown in
It will be noted that the outer joists of the opposed side walls 36, 38 are connected to the outer joists of the ground floor 10 and the ceiling structure 20 (that is, the lower joists of the floor and the upper joists of the ceiling structure), while the inner joists of the side walls are connected to the inner joists of the ground floor and the ceiling structure. The ends of the joists are connected for example using metal wall plates and screws. The inner and outer joists of the front and rear walls 22, 28 are similarly connected respectively to the inner and outer joists of the ground floor 10 and the ceiling structure 20.
Once the inner and outer surfaces of the framework have been covered with boards, this construction provides a void 40 that extends continuously around all four external walls 22,28,36,38, the ground floor 10 and the ceiling structure 20. Subsequently, this void 40 is filled with a thermal insulating material to provide an insulating layer that extends continuously and seamlessly around all external sides of the building.
The upper floor structure 12 also includes a void between the upper and lower joists, but in this embodiment the upper floor void is separated from the void in the surrounding walls by the ring beam 16, which is attached to the inner joists of the walls. Therefore, when the insulating material is injected into the walls, it does not flow into the upper floor void: it is not needed in this location as the upper floor 12 does not form an external surface of the building. However, if it is desired to provide an insulating layer within the upper floor structure, for example to reduce the flow of heat within the building, this can be achieved by providing a number of holes in the ring beam 16 so that the insulating material can flow into the upper floor void.
Alternatively, as shown in
Further details of the building structure are illustrated in
Details of the foundations are shown in
Details of the completed building structure are shown in section in
The ground below the floor trusses 10 is covered with a 75 mm layer of sand/cement screed 58 over a 100 mm layer of compacted hardcore 60. The damp proof membrane 62 is laid over the screed layer and extends outwards between the side walls 38 and the ground beams 56. The edge of the DPM 62 is taken upwards to cover the lower part of the wall structure 38, typically to a height of about 500 mm. The outer surface of the wall structure is covered with an 18 mm layer of OSB 64 (the lower part of which is covered by the DPM), followed by a 60 mm layer of EPS insulating board 66, and is finished with a layer of a chosen rendered cladding 68. The lowest part of the wall is protected by a moulded plastic damp proof course 70, which is fitted over a batten 72 that fixes the DPM over the vertical OSB board. The inner surface of the wall structure is covered with an 18 mm layer of OSB 73.
A method of constructing a building is illustrated schematically in
Step 1 illustrates an early stage of construction. The top soil has been removed from the building site, leaving a shallow excavation 74 covering the floor area of the building. A series of foundation holes 76 have been excavated. In step 2, concrete is poured into these holes to form a set of concrete foundation pads 78. These two steps of the construction method are conventional and so will not be described further.
Concrete ground beams 56 are then laid across the foundation pads 78 to form the base structure of the building (step 3). The area between the beams is then filled with hardcore 60 and covered with concrete/sand screed 59 (steps 4-5). Scaffolding 80 is then erected around the building site (step 6): the scaffolding erected across the front of the building has been omitted for the sake of clarity. A damp-proof membrane (DPM) 62 is laid across the beams 56 and the screed 58 (step 7). Alternatively, if sub-floor ventilation is required, the screed may be omitted: the damp-proof membrane 62 is then simply laid across the beams 56.
In order to construct the floor 10 a predetermined number of previously assembled trusses 2 are laid across the beams 56 so that they extend at right angles to the beams across the width of the building (step 8). The trusses 2 are arranged edgewise with respect to the beams 56, so that in each truss one of the joists is located vertically above the other joist. The upper joist forms an upper part of the floor structure, while the lower joist forms a lower part of the floor structure.
Correct spacing of the trusses 2 may be ensured by use of a comb-shaped template (not shown) having a plurality of recesses for receiving the ends of the trusses. After the trusses have been secured in position, the template may be removed. Alternatively, the spacing can be set by fitting pre-cut timber spacer elements between the trusses. The trusses are arranged so that they lie parallel to one another, typically with a centre-to-centre separation of 600 mm (although the separation may for example be in the range 100-800 mm).
After laying the trusses forming the floor 10, ground floor decking 54 of 18 mm OSB is laid to provide an accessible working surface (step 9). The next step is to erect another set of trusses to form a side wall 38 of the building (step 10). Again, the trusses 2 of the walls are normally preassembled and coded ready for erection. Each wall truss 2 is connected to an end of one of the floor trusses, so ensuring correct spacing of the wall trusses. The wall trusses are arranged vertically, with one joist on the inner side of the wall and the other joist on the outer side of the wall. Correct spacing of the upper ends of the vertical trusses 2 is ensured by clipping the trusses to scaffold clips 82 previously attached to the scaffolding. This process is repeated to erect the trusses of the other side wall 36 (step 11).
Although not shown in the drawings, battens may optionally be attached temporarily to the vertical trusses to hold them in position.
After erecting the vertical trusses that form the structure of the side walls 36,38, the next stage is to attach the ring beams 16 to side walls and assemble the upper floor structure 12 by attaching horizontal trusses to the ring beams (step 12). If required, a stair trimmer may also be attached at this stage. The upper floor decking 84 of 22 mm OSB is then laid on the upper floor trusses (step 13).
The next stage is to attach more preassembled trusses to form the ceiling structure 20 (step 14). The horizontal trusses are attached to the upper ends of the vertical trusses of the opposed side walls to form the ceiling structure 20. The correct spacing of the ceiling trusses is ensured by attaching them to the previously erected side wall trusses.
The trusses forming the rear wall 24 are then inserted and attached to the trusses of the floor structure 10, the ceiling structure 20 and the side walls 36,38 (step 15). The trusses forming the front wall 22 are assembled in a similar manner (step 16).
The next step is to apply external cladding 64 to the framework (step 17). The cladding typically includes a layer of 18 mm OSB, which is attached to the outer surfaces of the framework to cover the front, rear and side walls. The OSB secures the trusses in position, so that the building is then self-supporting. The floor structure is connected to the foundations 10 above the DPC level, and is connected through the OSB outer sheathing layer into the structural walls, thus holding the building in position. The DPM 62 is dressed up and fixed to cover the lower part of the external cladding 64. The rigid external DPC 70 is then attached to all exposed elevations (step 18).
This completes the construction of the basic framework of the building. It will be appreciated that at this stage the framework is entirely open on the inside, which allows easy inspection of all elements of the structure for compliance with building regulations. Although not shown in the drawings, services (for example, electricity and water) or conduits for those services can also be attached at this stage to the framework.
Roof trusses 52 are then located and fixed in position (step 19). Internal cladding 57 is attached to the inner surfaces of the framework and external cladding 58 is attached to the outer surfaces of the framework, covering the walls and the ceilings (step 20). Any suitable materials may be used, for example plasterboard or fireboard for the walls and the roof structure, and OSB, chipboard or floorboards for the floor. Doors and windows are also inserted.
This completes the main structure of the building. It should be noted that the void 40 between the inner and outer sheaths of the framework is entirely open. This void extends substantially continuously all around the framework of the building, including the walls, the floor and the roof structure. In this context, the term “roof structure” includes the ceiling structure and the external roof, as either of these structures may provide the void that is subsequently filled with an insulating material.
The void 40 in the walls, floor and roof structures is then filled by pumping a suitable insulating material 86 under pressure into the void. Any suitable insulating material may be used including, for example, expanding foam or EPS pellets. The insulating material 86 completely fills the void and provides a substantially continuous insulating layer that extends through the walls, the floor and the roof structure of the building, and fills any gaps in the frame boarding.
Finally, internal fitting-out of the building can be completed, and the external walls and roof can be covered in insulation boarding and external finishes including, for example, render or brick, cladding, roof tiling and so on.
In the embodiment shown in
In the alternative arrangement shown in
The scaffold clip 82 that is used when erecting the framework of the building is shown in
In use, the scaffold clips 82 are attached at the appropriate spacing to a horizontal scaffold pole of the scaffolding 80 that is erected around the construction site, so that the support elements 98 are arranged one vertically above the other.
Then, as depicted in
A spacing and fixing tool 106 used when attaching the external insulation and cladding boards 66, 68 depicted in
In use, as the external insulation and cladding boards 66, 68 are secured to the framework of the building as depicted in
Number | Date | Country | Kind |
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0906278.7 | Apr 2009 | GB | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/GB2010/000700 | 4/7/2010 | WO | 00 | 12/20/2011 |
Publishing Document | Publishing Date | Country | Kind |
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WO2010/116136 | 10/14/2010 | WO | A |
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