GB2452492A

GB2452492A - Improvements in or relating to floor/roof structures

Info

Publication number: GB2452492A
Application number: GB0717176A
Authority: GB
Inventors: Philip Carney
Original assignee: Weyerhaeuser Products Ltd
Current assignee: Weyerhaeuser Products Ltd
Priority date: 2007-09-04
Filing date: 2007-09-04
Publication date: 2009-03-11
Also published as: GB0717176D0

Abstract

The disclosure relates to a floor structure 10 for a timber frame building. The structure is formed in timber and consists of parallel joists 11 bounded by rimboards 12 where the structure is intended to be built into a wall having a timber frame e.g. a party wall. Each rimboard is a laminated board having an outer lamination 12a remote from the joist structure formed in timber and an inner lamination 12b adjacent the joist structure formed in a fire resistant foam to resist spread of fire from the floor structure to the wall to which the structure is mounted.

Description

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IMPROVEMENTS IN OR RELATING TO FLOOR/ROOF STRUCTURES This invention relates to floor/roof structures particularly although not exclusively for use with timber frame walls such as party walls.

In buildings where timber floor/roof structures are supported on timber framed party walls, there is a risk of fire spreading through a building between floor/roof perimeters and wall structures. It is an object of the present invention to resist the spread of a fire from a floor/wall structure of a building into the adjacent timber framed wall structure.

This invention provides a floor/roof support structure for use in a timber frame building, the structure being formed in timber and having a rimboard bounding the structure on one or more sides thereof where the structure is intended to be built into a wall having a timber frame (e.g. a party wall), wherein said rimboard is a laminated board having an outer lamination remote from the structure formed in timber and an inner lamination adjacent the structure formed in a fire resistant foam to resist spread of fire from the floor/roof structure to a wall to which the structure is mounted. The arrangement thus provides a single member of fire resistant product.

Preferably the laminated rirnboards having an outer lamination of timber and an inner lamination of fire resistant foam are provided on each side bounding the floor/roof structure to be built into a timber frame wall structure.

The floor structure may comprise a support structure as claimed in claim 1 or claim 2, comprising a set of spaced parallel extending timber joists, a first pair of laminated rimboards extending transversely to the joists being secured to the respective sets of ends of the joists with the ends of the joists abutting the laminations of fire resistant foam and a second pair of laminated rimboards extending parallel to the joists and being secured to the ends of the first pair of rimboards.

In addition compression blocks may be secured to the sides of the rim plates facing the floor structure, the compression blocks abutting the fire resistant foam lamination to give additional stability to the structure.

More specifically the compression blocks may be provided on the inside of the rim plate or rim plates where there is a join in the lamination of fire resistant foam.

In any of the above arrangements the fire resistant foam may comprise a graphite impregnated foam material.

Also in any of the above arrangements deck panels may be mounted on the floor structure.

The invention also provides a laminated fire resistant building panel comprising an outer lamination of a timber material and an inner lamination of a fire resistant plastics foam bonded to the outer lamination.

The following is a description of a specific embodiment of the invention, reference being made to the accompanying drawings in which: Figure 1 is a perspective view of a part of a floor S structure for a building; Figure 2 is a more detailed view of the arrangement of Figure 1; Figure 3 is a perspective view of two side by side floor structures built into a timber framed wall panel; Figure 4 is a perspective view of the arrangement of Figure 3F and Figure 5 is a perspective view of another side of the floor structure built into a wall structure with the joists running parallel to the rimboard.

Riniboards are used as edge binders for timber floor assemblies, and also serve a purpose as fire separating elements. These comprise "laminated strand" timber planks which are faced on one side with Fireseal F036, a graphite impregnated foam material bonded together using a suitable heat resistant structurally strong adhesive.

The rimboard timber is of TimberStrand� laminated strand lumber (LSL), a high strength engineered timber, with a thickness of 35mm and a width equal to the joist depth (see below). The specification and properties of the foam layer is given below.

The rimboards are used as a transverse edge binding system for complete room sized floor assembly, with the rimboards fastened to the ends of the TJI� Joists. The rimboard's foam facing is orientated towards the joist ends with 75mm long Simpson Strong Tie" screws used for locating the rimboard to align with the upper and lower chords of the joists. Screw fixtures equivalent to this type may be used subject to agreement between Weyerhaeuser Products Ltd. and IFC. One screw is used into each of the chords (i.e. top and bottom).

The floor systems may be assembled as complete units by crane on top of the head plates of the timber frame walls below the floor level, i.e. the walls below support the floor cassettes. The outer face of the cassette rimboards is installed to align with the "cavity edge" of the wall skin, and thus maintain the 50mm (nominal) air gap separation in the cavity.

To increase the loadbearing capabilities of the rimboard, compression blocks are nailed to the foam face of the rimboard in between joists at 600mm maximum centres.

These blocks are 89mm x 38mm (minimum) in section and have a length equal to that of the rimboard width. When the joists and rimboards are assembled as a prefabricated floor cassette, these compression blocks are on the inner (ceiling void) face and fit exactly between the underside of the decking and the wall frame head plate on which the cassette rests.

The positions of the compression blocks along the run of rimboard are not critical but should be positioned over any vertical joints in the foam material, whilst ensuring that the maximum spacing of the blocks does not exceed 600mm centres.

Rimboards are also used on the longitudinal edges of the floor cassettes, fixed parallel to the outer joists and with the void face coincident with the cavity face of the timber wall frames above and below. In this case, no joists are fastened to the rirnboard, but the line outer joist is coincident with the inner face of the timber wall frames.

Fireseal F036 is an acoustic insulating foam material, manufactured by Carpenter Ltd., and is supplied in a sheet form which can be machined or cut to the required size. In this case the F036 is 12mm thick with width to match that of the rimboard, and has the following properties: Density: >90 kg/m3 Colour: Dark Grey Thickness: 5mm to 100mm Fire propagation index: <12 Surface spread of flame: Class 1' Building Regs (ADB): Class 0' The joists are TJI� Joists manufactured by Weyerhaeuser Products Ltd. of the depth appropriate to the span. The joists consist of Microlam� LVL minimum Grade 2.OE top and bottom flanges, nominally 35mm or 38mm deep x 38mm to 89mm wide, and a Performance p1us Oriented Strand Board (OSB) web. Where 38mm wide flanges are specified (TJI� 105 and TJI�/Pro'M 150 series joists), then their use shall be subject to the additional requirements of Sections 4.3 and 4.4 of this report.

The following I-joist sizes are specified, flange dimensions are depth x width in mm: TJI� 105: 35 x 38mm flange, depths: 220, 241 and 302mm TJI� 110: 35 x 45mm flange, depths: 220, 241 and 302mm TJI� 360: 35 x 58mm flange, depths: 220, 241, 302, 356 and 406mm TJI� 560: 35 x 89mm flange, depths: 220, 241, 302, 356 and 406mm TJI�/Pro series 150: 38 x 38mm flange, depths: 241 and 302mm TJI�/Pro series 250: 38 x 45mm flange, depths: 200, 241, 302, 356 and 406mm TJI�/Pro series 350: 38 x 58mm flange, depths: 200, 241, 302, 356 and 406mm TJI�/Pro series 550: 38 x 89mm flange, depths: 200, 241, 302, 356 and 406mm The joists will be able to carry up to 100% of their maximum allowable stress. The joists are to be installed at not more than 600mm centres and will be braced as required.

The ends of the joists are supported on timber or masonry plates and have a bearing of not less than 45mm and braced at the end with a suitable trimmer joist or closure.

Referring now to Figure 1 of the drawings, there is shown a floor structure for a timber frame building indicated generally at 10 and comprising a set of spaced parallel I-beam form joists 11 which are bounded on each side of the floor structure by rimboards 12.

Each rimboard is of laminated construction comprising an outer wall l2a of a timber based product known as "Timber Strand" and an inner lamination 12b bonded to the outer wall of a fire resistant foam material such as "Fireseal F036" -.7-which is an acoustic insulating foam material manufactured by Carpenter Ltd. as described above.

The fire resistant foam laminations of each rimboard around the floor structure face inwardly of the floor structure to protect the lamination and the structure to which it is connected from spread of fire from the floor structure.

In the case where a rimboard extends transversely to the ends of a set of joists, the joist ends abut the inner fireproof lamination 12b on the rimboard and are secured to the rimboard by means of screws or nails driven through the rirnboard.

Compression blocks 13 are secured to the inner side of the rirnboard at spaced locations and in particular adjacent the joists to assist in supporting the wall above.

As indicated above, rimboards 12 are provided on required sides of the floor structure. On the sides of the floor structure extending parallel to the joists, the rimboards extend parallel to the joists and are secured at their respective ends to the ends of the rimboards which run transversely to the joists.

Referring now to Figures 3 to 5 of the drawings, two side-by-side timber framed wall structures 14, 15 are shown into either side of which floor structures 10 are built.

Each wall structure has a lower part 16 terminating in a top plate 17 on which the peripheral portion of a deck structure sits. Decking 18 is located on the floor structure arid the upper parts of the wall structure 19 have sole plates 20 which sit on the outer edges of the decking.

The fire resistant foam lamination on the inside of the S rirnboards provide "one hour" protection against fire spreading from the floor structure to the adjacent floor structure.

It will be appreciated that many modifications may be made to the above described embodiment without departing from the scope of the invention. For example the support structure may form part of a roof structure for a building.

Claims

CLPIMS: 1. A floor/roof support structure for use in a timber frame building, the structure being formed in timber and having a rimboard bounding the structure on one or more sides thereof where the structure is intended to be built into a wall having a timber frame (e.g. a party wall), wherein said rirnboard is a laminated board having an outer lamination remote from the structure formed in timber and an inner lamination adjacent the structure formed in a fire resistant foam to resist spread of fire from the floor/roof structure to a wall to which the structure is mounted.
2. A support structure as claimed in claim 1, wherein laminated rimboards having an outer lamination of timber and an inner lamination of fire resistant foam are provided on each side bounding the floor/roof structure.
3. A support structure as claimed in claim 1 or claim 2, comprising a set of spaced parallel extending timber joists, a first pair of laminated rimboards extending transversely to the joists being secured to the respective sets of ends of the joists with the ends of the joists abutting the laminations of fire resistant foam and a second pair of laminated rimboards extending parallel to the joists and being secured to the ends of the first pair of rimboards.
4. A support structure as claimed in any of claims 1 to 3, wherein compression blocks are secured to the sides of the rimboard or rimboards facing the floor structure, the -10 -compression blocks abutting the fire resistant foam lamination.
5. A support structure as claimed in claim 4, wherein compression blocks are provided on the inside of the rimboard or rimboards where there is a join in the lamination of fire resistant foam.
6. A support structure as claimed in any of the preceding claims, wherein the fire resistant foam comprises graphite impregnated foam material.
7. A support structure for a floor as claimed in any of the preceding claims, wherein deck panels are mounted on the floor structure.
8. A laminated fire resistant building panel comprising an outer lamination of a timber material and an inner lamination of a fire resistant plastics foam bonded to the outer lamination.
9. A building panel as claimed in claim 8, wherein the fire resistant foam comprises a graphite impregnated foam material.

848627; GCB; UB