AU2013100047B4

AU2013100047B4 - Fire Resistant Building

Info

Publication number: AU2013100047B4
Application number: AU2013100047A
Authority: AU
Inventors: David Leonard Cox
Original assignee: Cox Arch Pty Ltd; Cox Architects Pty Ltd
Current assignee: Cox Architects Pty Ltd
Priority date: 2013-01-17
Filing date: 2013-01-17
Publication date: 2013-10-24
Anticipated expiration: 2021-01-17
Also published as: AU2013100047A4

Abstract

A fire resistant building comprises a wall structure (20) formed of fire resistant material(s), and a roof structure (10) comprising a plurality of panels (11) of fire resistant material(s) other than aerated concrete arranged to form a fire resistant layer. The panels (11) may be made of magnesium oxide board or fibre cement board. The fire resistant layer of roof panels (11) extends to the top of the wall structure (20) and forms a substantially closed join with the wall structure, such that wall structure (20) and layer of panels (11) form a continuous fire barrier. The building is particularly suitable for use in areas vulnerable to bushfires.

Description

EDITORIAL NOTE 2013100047 There are six pages of the description only FIRE RESISTANT BUILDINGS Field of the Invention [0001] This invention relates to fire resistant buildings and their construction. In particular, the invention is directed to a method of constructing buildings which achieve a high fire rating, and to buildings constructed by such method. Background Art [0002] Mere reference to background art herein should not be construed as an admission that such art constitutes common general knowledge in relation to the invention. [0003] With increasing encroachment of houses and other buildings into forested areas, the growth of trees and other vegetation in close proximity to buildings, restrictions on clearing of vegetation, and prolonged dry weather periods, many building now face an increased risk of damage from bushfires. [0004] Various methods of constructing fire resistant buildings have been proposed. These generally use fireproof or fire resistant building materials, but tend to retain conventional building designs. [0005] In a conventional building, the eaves are particularly vulnerable to fires as they are usually made largely of wood, plaster or other material with a low fire rating, and are exposed to flames below them, The eaves effectively 'trap' heat from the flames and/or bear the brunt of the heat from the hottest parts of the flames, and therefore are more likely to burn. [0006] Although there are fire rated ceiling systems available, these are generally designed to prevent fires from penetrating the roof space from the inside of the building. The known systems are not particularly effective in preventing fire penetration from the outside the building. [0007] Australian innovation patent no 2008100775 discloses a method of constructing a fire resistant building using aerated concrete blocks. Although the aerated concrete blocks have been found to be advantageous over conventional concrete blocks, they are still quite bulky and heavy, and relatively expensive. Moreover, they are not readily obtainable in all areas, particularly rural areas.

[0008] It is an aim of this invention to provide a method of constructing fire resistant buildings, and buildings made by such method, which overcomes or ameliorates one or more of the disadvantages or problems described above, or which at least provides a useful alternative. Summary of the Invention [0009] In one broad form, the present invention provides a method of constructing a building comprising the steps of: forming a wall structure using fire resistant material(s); forming a roof structure comprising a plurality of panels of fire resistant material(s) other than aerated concrete, arranged to form a fire resistant layer; wherein the fire resistant layer of panels extends to the top of the wall structure and forms a substantially closed join with the wall structure, such that wall structure and layer of panels form a continuous fire barrier. [0010] In another broad form, the present invention provides a building comprising: a wall structure formed of fire resistant material(s); and a roof structure comprising a plurality of panels of fire resistant material(s) other than aerated concrete, arranged to form a fire resistant layer; wherein the fire resistant layer of panels extends to the top of the wall structure and forms a substantially closed join with the wall structure, such that wall structure and layer of panels form a continuous fire barrier. [0011] In the preferred embodiment, the panels are formed from magnesium oxide board or fibre cement board. [0012] Advantageously, the wall structure also includes sheeting comprising panels formed from magnesium oxide board or fibre cement board.. [0013] Roof sheeting is suitably mounted above the plurality of panels forming the fire resistant layer. Even if the roof sheeting is lost or breached, e.g. in a fire, the continuous fire barrier will still protect the building regardless of the state of the roof sheeting. [0014] In order that the invention may be more readily understood and put into practice, one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings.

Brief Description of the Drawings [0015] Figure 1 is sectional perspective view of part of a building constructed in accordance with one embodiment of the invention. [0016] Figure 2 is sectional end elevation of part of the building of Figure 1. [0017] Figure 3 is an enlarged view of part of the building of Figure 2. [0018] Figure 4 is a sectional perspective view of the building of Figure 1. [0019] Figure 5 is sectional perspective view of part of the building of Figure 4. [0020] Figure 6 is a sectional perspective view of part of a building constructed in accordance with another embodiment of the invention. [0021] Figure 7 is a cross section view of the building of Figure 6 constructed on a concrete slab on ground. [0022] Figure 8 is a cross section view of the building of Figure 6 constructed on a raised floor. [0023] Figure 9 is a cross sectional view of part of the roof structure of the building of Figures 7 and 8 showing an optional gutter and fascia support arrangement. [0024] Figure 10 is a cross sectional view of another part of the roof structure of the building of Figures 7 and 8. [0025] Figure 11 is a cross sectional view of part of the roof structure of the building of Figures 7 and 8 showing an alternative optional gutter and fascia support arrangement. Description of Preferred Embodiments [0026] Figures 1 to 5 illustrate part of a two story building constructed in accordance with one embodiment of the invention. In this embodiment, the building comprises a roof structure 10 of the type having a sub-structure formed by steel joists or rafters 12, which are supported on walls 20. [0027] As shown in the Figures 1 to 5, the roof structure 10 comprises a plurality of panels 11 supported on the joists or rafters 12 in an elevated position. The panels 11 are 4 rectangular panels, which are arranged transversely to the rafters 12, with adjacent panels contiguous or abutting. Although butt jointed panels 11 are shown, the ceiling panels can alternatively be provided with a "tongue and groove" configuration on their edges so that they may engage or interlock with each other. The panels 11 effectively form a continuous layer. The panels can be fixed in place on the rafters 11 by screws 16. [0028] The panels 11 are made of a material with high fire rating, such as magnesium oxide board or fibre cement, or fire resistant material other than aerated concrete. [0029] The layer of panels 11 extends all the way down to the top of the walls 20, and preferably terminates at the top of the walls 20. The layer of panels 11 joins the top of the walls 20, and there is no gap between them. [0030] The walls 20 also comprise sheet material with high fire rating, such as magnesium oxide board or fibre cement or fire resistant material other than aerated concrete, which is fixed to the outside of a stud wall frame or other wall structure. The lower roof panels are contiguous or abutting with the upper wall panels so that they effectively a substantially continuous fire barrier. [0031] Roofing material 14, such as metal sheeting or other suitable cladding, may be placed on the layer of panels 11 by being screwed or otherwise fixed to metal roof battens 13 fixed to and through the panels 11. The battens may be easily screwed or otherwise fastened through the panels to the roof sub-structure below. Insulation 15 may be inserted between the panels 11 and roof cladding 14 if required. The roofing material 14 may extend a short distance beyond the walls 20 for drainage, but preferably there should be no large eaves overhangs. [0032] Figs 6 to 10 illustrate part of a single story building constructed in accordance with another embodiment of the invention. In this embodiment, the building comprises a roof structure 10A of the type having a sub-structure including trusses 23. These trusses are supported on walls 20 in a similar manner to the embodiment of Figures 1 to 5. [0033] The single story building may be mounted on a concrete floor slab on the ground as shown in Fig. 7, or on an elevated floor structure as shown on Fig. 8.

5 [0034] As shown in the Figures 6 to 10, the roof sub-structure includes fire resistant panels 11 supported on the trusses 23, extending transversely to the trusses 23, with adjacent panels contiguous or abutting to form a continuous layer. [0035] The layer of panels 11 extends all the way down the roof and down the outside of the walls 20, to effectively a substantially continuous fire barrier. [0036] In the embodiment of Fig. 8, the layer of panels 11 may also extend under the floor 24 of the building so that the whole building in enveloped in a fire barrier. [0037] A cantilevered gutter and fascia support arrangement 25 (as shown in Fig. 9) or a wall-mounted cantilevered gutter and fascia support arrangement 26 (as shown in Fig. 11) may optionally be provided. In the latter case, eaves lining may suitable be affixed to the underside of the support arrangement 26. [0038] The roofing material 14, e.g. metal sheeting or other suitable cladding, is fixed to the panels 11 as described above in relation to the embodiment of Figs. 1 to 5. [0039] The methods of constructing fire resistant buildings described above, and the resultant buildings, have several advantages, including: e The layer of roof sub-structure panels and the walls form a contiguous construction which creates a continuous fire barrier; * The roof sub-structure panels provide shear resistance and bracing for the roof, thereby increasing the wind rating of the building; * There is little or no eave formation, and any eave created by the roofing material is outside the continuous fire barrier formed by the layer of roof sub-structure panels and the walls. * The roof sub-structure panels are much lighter than aerated concrete panels and easier for workers to handle. * The relatively light roof sub-structure panels enable the method to be used to construct fire resistant transportable buildings. * The construction of the invention is applicable to different building types, such as those shown in the drawings.

6 e In conventional buildings using metal roof sheeting, the roof sheeting will deform under extreme fire attack. The roof is thereby breached and the fire will enter the building via the roof (or eaves). Buildings constructed according to the illustrated embodiments of the invention are not solely dependent on adequate fire resistance of the roof sheeting to protect a building. The roof sheeting is separated from the building structure below it by an additional fire barrier provided between the roof sheeting and the building structure. In the illustrated embodiments, should the roof sheeting deform or be breached by fire, the fire barrier 11 will still protect the building regardless of the state of the roof sheeting. In each of the building types described herein with reference to the drawings, the roof is constructed is such a way as to permit the roof sheeting to deform or be discarded without damaging the roof sub-structure below. The fire integrity of the roof sub structure below the roof membrane or sheeting is more important than trying to protect the roof sheeting. In this way, the sheeting is considered a sacrificial element of the design and the construction permits the roof sheeting to deform without compromising the fire integrity of the roof structure below. [0040] It is to be understood that the terminology employed above is for the purpose of description and should not be regarded as limiting. [0041] The foregoing embodiments are intended to be illustrative of the invention, without limiting the scope thereof. The invention is capable of being practised with various modifications and additions as will readily occur to those skilled in the art. [0042] Accordingly, it is to be understood that the scope of the invention is not to be limited to the exact construction and operation described and illustrated, but only by the following claims which are intended, where the applicable law permits, to include all suitable modifications and equivalents within the spirit and concept of the invention. [0043] Throughout this specification, including the claims, where the context permits, the term "comprise" and variants thereof such as "comprises" or "comprising" are to be interpreted as including the stated integer or integers without necessarily excluding any other integers.

Claims

1. A method of constructing a building comprising the steps of: forming a wall structure using fire resistant material(s); forming a roof sub-structure including a plurality of panels of fire resistant material(s) other than aerated concrete, arranged to form a fire resistant layer; wherein the fire resistant layer of panels extends to the top of the wall structure and forms a substantially closed join with the wall structure, such that the wall structure and the roof sub structure form a continuous fire barrier.

2. A building comprising: a wall structure formed of fire resistant material(s); and a roof sub-structure including a plurality of panels of fire resistant material(s) other than aerated concrete, arranged to form a fire resistant layer; wherein the fire resistant layer of panels extends to the top of the wall structure and forms a substantially closed join with the wall structure, such that the wall structure and the roof sub structure form a continuous fire barrier.

3. A method as claimed in claim 1, or a building as claimed in claim 2, wherein the panels are made of magnesium oxide board or fibre cement board.

4. A method as claimed in claim 1, or a building as claimed in claim 2, wherein roof sheeting is mounted above the plurality of panels forming the fire resistant layer.

5. A method as claimed in claim 1, or a building as claimed in claim 2, wherein the wall structure includes sheeting comprising panels formed from magnesium oxide board or fibre cement board.