GB2574452A

GB2574452A - A fire barrier for a cavity wall

Info

Publication number: GB2574452A
Application number: GB1809349.2A
Authority: GB
Inventors: Ruding Paul
Original assignee: ACS Stainless Steel Fixings Ltd
Current assignee: ACS Stainless Steel Fixings Ltd
Priority date: 2018-06-07
Filing date: 2018-06-07
Publication date: 2019-12-11
Anticipated expiration: 2038-06-07
Also published as: GB201809349D0; GB2574452B

Abstract

Comprises a metal plate 10 secured to a masonry support bracket 11, which can be secured to the inside of a cavity wall and support the masonry of the outer skin 17. The plate projects from the bracket and spans the cavity abutting or is embedded in two masonry of the outer skin. The plate can be attached to the top or the bottom of the bracket and has an L shaped cross section with a leg 18 and a foot 19. In use the foot can be clamped between the bracket and the cavity wall. A masonry support plate 14 can also be secured to the bracket adjacent to the metal plate. Fabricating the item from stainless steel equal to or thicker than 0.5mm is preferable.

Description

A FIRE BARRIER FOR A CAVITY WALL

The present invention relates to a fire barrier, sometimes called a fire sock, for use in cavity walls.

Conventionally, fire barriers or fire socks may comprise mineral wool or other compressible non-combustible material that is designed to be compression fitted within a cavity wall to form a barrier. The barrier must bridge the cavity between the skins of the cavity wall so that it can restrict the spread of smoke and flames within the cavity should a fire arise. One disadvantage with such barriers is that if not fitted correctly they can become dislodged and slip within the cavity thereby compromising their effectiveness should a fire break out. Another disadvantage is that they tend to take up a considerable amount of space in the confined area of the cavity, which reduces the space available to fit masonry support structures and the like. It also makes the fitment of such structures more difficult during the construction process.

An alternative form of fire barrier or fire sock comprises a cast-in metal plate that is mortared into the inner and outer masonry skins of a cavity wall so that it bridges the cavity. The plate is again designed to form a barrier preventing the spread of smoke and flames. The problem with such simple metal barriers is that they are awkward to fit. Typically, the inner skin of a cavity wall comprises blockwork whereas the outer skin comprises bricks. This means that the mortar courses in the brick skin and the blockwork skin may not line up horizontally, making it difficult to fit the plates where they are required. Also, the plates have to be cut to fit over and around masonry supports, which compromises their effectiveness, so that gaps between the masonry supports and the plates have to be filled with an appropriate filler, which again adds to the construction time and can lead to such gaps being left open.

The object of the present invention is to provide a fire barrier for use in a cavity wall that overcomes the aforementioned disadvantages of conventional barriers.

According to the present invention there is provided a fire barrier for use in a cavity wall comprising a metal plate that is rigidly secured to at least one masonry support bracket, which is adapted to be secured to an inner skin of the cavity wall to support masonry of an outer skin of the cavity wall, the plate projecting outwards from the bracket and adapted to span the cavity such that in use it abuts the outer skin.

Preferably, the metal plate is secured to the top or to the bottom of the masonry support bracket.

Preferably also, the metal plate projects outwards from the bracket sufficiently such that in use it abuts and can be secured between two adjacent masonry courses of the outer skin.

Other preferred but non-essential features of the invention are described in the dependent claims.

The present invention will now be described by way of example with reference to the accompanying drawings, in which:Fig. 1 is a perspective view of a conventional, masonry support arrangement;

Fig. 2 is a perspective view of a first embodiment of fire barrier in accordance with the present invention;

Fig. 3 is a side view of the fire barrier shown in Fig, 2 but to an enlarged scale; and

Figs 4 and 5 are views similar to Figs. 2 and 3 but of a second embodiment of fire barrier in accordance with the present invention.

A conventional masonry support arrangement 1 is shown in Fig. 1. It comprises a series of masonry support brackets 2 to which a planar masonry support plate 3 is secured. In use, as shown, the brackets 2 are adapted to be adjustably secured to a support structure 4, which is typically an inner skin of a cavity wall, by means of fasteners 5. This enables the position of the brackets 2 relative to the inner skin 4 to be finely adjusted thereby to enable the support plate 3 to project from the brackets 2 at the correct height so that it can locate between two adjacent courses 6, 7 of brickwork forming the part of an outer skin 8 of the cavity wall. The support plate 3 thereby supports the masonry about it.

Turning now to the invention, in a first embodiment, as shown in Figs. 2 and 3, a fire barrier comprises a metal plate 10 that is secured to the base of at least one masonry support bracket 11, which may otherwise be of conventional construction with a back plate 12 and integrally formed projecting side plates 13. The back plate 12 is adapted to be secured, in use, to a support structure (not shown) comprising an inner skin of a cavity wall, for example by fasteners (not shown). The side plates 13 are adapted to be secured to a support plate 14, which is itself adapted to locate between two adjacent courses 15, 16 of masonry forming part of an outer skin 17 of the cavity wall, the support plate 14 thereby supporting the masonry of the outer skin 17 above it. In the illustrated embodiment the support plate 14 is integrated with the bracket 11 by being welded thereto. However, in other embodiments, the support plate 14 may comprise a separate component that is secured to the side plates 13 of the bracket during construction, typically by slotting into apertures provided in the side plates 13.

The metal plate 10 is preferably welded to the bracket 11 or to a series of spaced brackets 11 and has an L-shaped cross-sectional profile, with a leg 18 and an integrally formed foot 19. The leg 18 is secured to the side plates 13 so that it projects outwards from the or each bracket n to an extent sufficient to span the cavity formed between the inner and outer skins of the wall. It will be appreciated that the leg 18 lies adjacent but below the support plate 14 when in use and while it does not need to project outwards from the bracket or brackets 11 to the same extent as the support plate 14 it projects sufficiently for it to abut the outer skin 17. Preferably, however, it projects sufficiently that it not only abuts the outer skin 17 but is located between the same adjacent courses 15, 16 of brickwork as the support plate 14 and is thereby mortared into the outer skin 17. The foot 19 lies adjacent the rear of the back plate 12 and may also be secured thereto by welding. In use, the foot 19 is therefore clamped between the or each bracket 11 and the inner skin (not shown) of the cavity wall. Hence, the metal plate 10 bridges and closes the cavity between the inner and outer skins of the wall. This restricts the spread of smoke and flames through the cavity should a fire arise.

A second embodiment of fire barrier is shown in Figs. 4 and 5. Here, a metal plate 20 is secured, preferably by welding, to the top of a bracket 11 or series of brackets 11, which are of identical construction to those described above and shown in Figs. 2 and 3. The metal plate 20 is also similar to the plate 10 described above but inverted so that its foot 19 depends down behind the back plate 12 of the bracket 11 and its leg 18 projects forwards. Again the leg 18 projects outwards from the bracket sufficiently to abut the outer skin 17 of a cavity wall and again preferably extends sufficiently to be located and secured between two adjacent courses of masonry 15, 16 of the outer skin 17.

In order to provide at least 30 minutes fire resistance, the metal plate 10, 20 of the barrier needs to be made of steel plate that is at least 0.5 mm thick. Preferably, however, the metal plate 10, 20 is comprised of stainless steel and has a thickness between 0.5 mm and 2.0 mm inclusive. Thicker plates have more rigidity, which improves their efficiency should a fire arise as they take longer to warp and buckle owing to the heat of a fire. Thicker plates also increase the fire resistance period to around 2 hours, which is an important consideration in high-rise structures where evacuation from upper floors may take longer than 30 minutes after a fire has broken out.

During construction of a building, the size, position and securement of the masonry support brackets 11 to an inner skin of a cavity wall is finely adjusted so that the support plate 14 readily locates between two adjacent courses of masonry in the outer skin 17. This ensures that the position of the metal plate 10, 20 is also finely adjusted at the same time so that it can do the same. The combination of the metal plate 10, 20 with the masonry support bracket 11 or brackets 11 therefore facilitates the positioning within a cavity of a fire barrier. In addition, it obviates the need for the barrier to be cut to slot over existing masonry support brackets 11 and maximizes the space available within the cavity to fit the masonry support brackets 11.

Hence, it will be appreciate that a fire barrier in accordance with the present invention provides considerable advantages over prior art barriers, simplifying both their construction and fitment.

Claims

1. A fire barrier for use in a cavity wall comprising a metal plate that is rigidly secured to at least one masonry support bracket, which is adapted to be secured to an inner skin of the cavity wall to support masonry of an outer skin of the cavity wall, the plate projecting outwards from the bracket and adapted to span the cavity such that in use it abuts the outer skin.

2. A fire barrier as claimed in Claim i, wherein the metal plate is secured to the top or to the bottom of the masonry support bracket.

3. A fire barrier as claimed in Claim 1 or Claim 2, wherein the metal plate projects outwards from the bracket sufficiently such that in use it abuts and can be secured between two adjacent masonry courses of the outer skin.

4. A fire barrier as claimed in any of Claims 1 to 3, wherein the plate has an L-shaped cross-sectional profile, with a leg and a foot, the leg comprising that part of said metal plate which projects outwards from the or each bracket to span the cavity and the foot comprising a second part of the metal plate that is adapted to be clamped, in use, between the or each bracket and the inner skin of the cavity wall.

5. A fire barrier as claimed in any of Claims 1 to 4, wherein the metal plate is welded to the or each support bracket.

5. A fire barrier as claimed in Claim 5, wherein a masonry support plate is secured to the or each support bracket and the leg of the metal plate is secured to the bottom of the bracket and projects outwards adjacent but below the support plate when in use.

6. A fire barrier as claimed in any of Claims 1 to 5, wherein the metal plate is comprised of steel and has a thickness of at least 0.5 mm.

7. A fire barrier as claimed in any of Claims 1 to 6, wherein the metal

5 plate is comprised of steel and has a thickness between 0.5 mm and

2.0 mm inclusive.

8. A fire barrier as claimed in any of Claims 1 to 7, wherein the metal plate is comprised of stainless steel.