GB2491090A

GB2491090A - An adjustable inter-cavity fire-proof barrier

Info

Publication number: GB2491090A
Application number: GB1104596.0A
Authority: GB
Inventors: Douglas Wilson Cullen; Martin William Milner
Original assignee: Intelligent Wood Systems Ltd
Current assignee: Intelligent Wood Systems Ltd
Priority date: 2011-03-18
Filing date: 2011-03-18
Publication date: 2012-11-28
Also published as: GB201104596D0

Abstract

The barrier comprises two parts, a rigid member 18 which is fixed to a first cavity wall 12 and extends across a portion of the gap, and an in-fill member 20 which is adjustable to extend to the other wall 14 to fill the gap. The rigid member is preferably treated with fire retardant, water repellent and an insect and fungi preservative. It may be a timber batten, or a fire resistant material. The in-fill is preferably flexible and compressible. It comprises either a length of mineral wool enclosed in a polythene sleeve, intumescent material, or a brick or steel sheet. The in-fill may be positioned in a channel on the rigid member. The upper surface of the rigid member preferably slopes downward away from the wall to allow moisture drainage. In use, the barrier limits flame spread together with heat and smoke movement between cavity walls in a building. The cavity is preferably between two timber frame panels or timber frame and masonry cladding.

Description

I

CAVITY BARRIER

The present invention relates to fire prevention and protection in building construction, and in particular to a cavity barrier S for limiting flame spread together with heat and smoke movement between cavity walls in a building.

Current construction methods for buildings provide a timber frame wall and an external rain screen cladding1 such as a masonry wall. Between these two walls a cavity exists. This cavity will typically only include wall ties, and any membrane overlaps. In the event of a fire, flames heat and smoke can travel up the cavity between the floors of the building? and also horizontally between internal walls or party walls.

Current building regulations require there to be cavity barriers located between the walls at regular intervals. Cavity barriers should provide at least 30 minutes fire resistance. Typically, a cavity barrier is formed from a batten which may be a solid timber batten designed to fit snugly between the walls. An alternative is to provide a length of non-combustible material such as mineral wool which is held within a polythene sleeve, tc fill the cavity. Flanges are located on the sleeve so that the sleeve can be fixed to one wall.

For ease of construction, cavity barriers are located on the timber frame before the masonry or external cladding wall is constructed. In this regard, it is difficult to determine the final width of the cavity. As a result? where a cavity batten is fixed to the timber wall, the batten may be removed if space is too tight. This breaches fire regulations. If the masonry wall, when constructed, leaves a cavity gap wider than the cavity batten, this provides an inefficient barrier, allowing smoke, heat and flames to pass the barrier and travel through the cavIty. This problem can also arise if the cavity expands after construction as a result of movement in either wall. Thus even S where the cavity barrier provided a seal on construction there is the possibility that the cavity batten will later allow heat and smoke to fill the void.

Where a lightweight sock is provided in the form of mineral wool enclosed in a polythene sleeve, this can easily be knocked off falling to the base of the cavity and being ineffectual. Even if the sock appears to be in place, higher construction of the masonry wall can result in materials dumped into the cavity such as excess mortar. This mortar, bearing upon the lightweight sock, will cause the sock to dislodge and fall into the cavity.

Additionally, the polythene sleeve is easily torn or punctured and as a result moisture in the cavity can penetrate the poiythene sleeve. Accordingly, the weight of collected water in the sock causes the sock to dislodge and also fall into the base of the cavity.

It is therefore an object of the present invention to provide a cavity barrier which obviates or mitigates at least some of the

disadvantages in the prior art cavity barriers.

According to a first aspect of the present invention there is provided a cavity barrier for use in a cavity gap between first and second walls of a building construction, the barrier comprising: a rigid member for fixing to a first wall and arranged to extend across a portion of the gap; and an in-fill member for bridging the remaining portion of the gap between the rigid member and the second wall, the in-fill member being adjustable to ensure the barrier spans the gap.

In this way, a cavity barrier is created which will always S bridge the gap between the first and second walls. The use of a rigid member provides support to a flexible member and so prevents the flexible member being dislodged. The use of a flexible member with a rigid member provides sufficient variability in the width of the barrier to ensure it fits snugly between the walls.

Preferably the rigid member is a timber batten. Preferably the rigid member is a solid timber batten. Such timber battens are familiar in construction and thus typical labourers are not presented with unfamiliar components.

Preferably the rigid member includes fixing means to affix the member to the first wall. By affixing the member to the wall a rigid immoveable support is created at a desired location in the cavity.

Preferably the rigid member has a width in a range of 20 to 35 mm to extend across the cavity. In this wayp a substantial portion of the gap is filled with the rigid member. More preferably the rigid member has a width of 25 mm. In this way, the rigid member will fill approximately half a typical cavity gap, these being 40, 50 and 60 mm in design.

Preferably an upper surface of the rigid member is at a tilt angle with respect to the first wall. In this way, water travelling down the first wall is directed along the surface of the rigid member and can drain through a weephole in the masonry wall if such an outlet is included.

Preferably, the rigid member includes a channel. The channel may be arranged to be opposite the second wall. The channel may aid affixing of the adjustable member to the rigid member by providing a bed.

Preferably, the rigid member is treated with a water repellent.

More preferably the rigid member is alsc treated with an insect and fungi preservative. These treatments prevent the rigid member from shrinking or decomposing in the construction.

Preferably the rigid member is treated with a fire retardant.

This will increase the fire resistant time of the cavity barrier to meet and exceed building regulations.

Preferably the in-fill member comprises a flexible material. In this way it is adjustable to fit in the remaining portion.

More preferably the in-fill member comprises a compressible material. In this way, a seal is created across the cavity.

The in-fill member may comprise a length of mineral wool contained within a polythene sleeve. Thus readily available materials may be used.

Preferably the in-fill member comprises a fire resistant material. The in-fill member may comprise a fire resistant rubber. Alternatively, the infill member may comprise a steel plate. Alternatively, the in-fill member may comprise an elongate section of fireboard. These materials ensure the cavity barrier meets the building regulations.

The in-fill member may comprise an intumescent material. Such material will swell under heat and can expand to fill the gap S when the member is subjected to heat such as wouid occur in a fire. The intumescent material may be applied as paint or in a strip. An expandable material provides an advantage in that the cavity barrier is known to fit within the cavity on construction and will seal the cavity in the event of a fire.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings of which: Figure 1 is a cross-sectional illustration of a cavity barrier located between first and second walls according to an embodiment of the present invention. Figures 1(a), (b) and (c) each represent the cavity barrier located in a cavity of varying widths; Figure 2 is a cross-sectional illustration of a cavity barrier located between first and second walls according to a second embodiment of the present invention. Figures 2 (a), (b) and (o) each represent the cavity barrier located in a cavity of varying widths; Figure 3 is a cross-sectional illustration of a cavity barrier located between first and second walls according to a third embodiment of the present invention. Figures 3 (a), (b) and (c) each represent the cavity barrier located in a cavity of varying widths; Figure 4 is a cross-sectional illustration of a cavity barrier located between first and second walls according to a fourth embodiment of the present invention. Figures 4(a) and (b) illustrate the arrangement in cavities of varying widths; Figure 5 is a cross-sectional illustration of a cavity barrier located between first and second walls according to a fifth embodiment of the present invention; Figure 6 is a cross-sectional illustration of a cavity barrier located between first and second walls according to a sixth embodiment of the present invention; Figure 7 is a cross-sectional illustration of cavity barriers located between walls at a party wall junction according to a further embodiment of the present invention; and Figures 8 (a) and (b) are cross-sectional illustrations of cavity barriers located between first and second walls according to further embodiments of the present invention.

Reference is initially made to Figure 1 of the drawings which illustrates a cavity barrier, generally indicated by reference numeral 10, according to a first embodiment of the present invention. Barrier 10 is in location between a first wall 12 and a second wall 14 with a cavity 16 there between. Cavity barrier comprises a rigid member 18 affixed to wall 12 and a flexible member 20 attached to the rigid member 18. The rigid member 18 extends across the gap between the walls 12,14 by approximately half the gap width. In-fill member 20 extents from the rigid member 18 to the inner surface 22 of the seccnd wail 14. By this arrangement, a seal is created between the walls 12 and 14.

Rigid member 18 comprises a solid timber batten, The batten has a first vertical surface 24 for location against the outer surface 26 of the inner wall 12. At an opposing end, the member 18 includes a surface 28 against which there is affixed the in-fill member 20. An upper surface 30 of the member 18 is sloped to provide a natural path from the inner surface 26 of the wall 12, down the surface 30 of the member 18, over the surface 32 of the in-fill member 20 to drain into a weephole 34 located in the masonry wall 14.

Rigid member 18 is attached to the timber wail 12 by nailing or any other suitable fixing means. In the embodiment shown the member has a width of 25 mm extending across the cavity 16. Most constructions provide for a cavity gap in the region of 40 to 65 mm and thus the rigid member 18 extends to approximately half the width of the gap.

To prevent the member 18 from shrinkage in use, the solid timber is treated with a water repellent. Such water repelients are known to those skilled in the art. The member 18 is also treated with an insect and fungi preservative. Such a preservative prevents timber from being decomposed, rotting or splitting in use.

Yet further the member 18 is treated with a fire retardant. The fire retardant will increase the time for a fire to spread through the cavity. This increases both the time for the building to be emptied of occupants and the time for the fire services to save the building from destruction.

The in-fiil member 20 is a polythene sleeve filled with lightweight non-combustible mineral wool. Such arrangements are as known in the industry and provide a compressible member within the cavity 16. In this embodiment, the polythene sleeve is rigidly attached to the member 18 at the surface 28.

The rigid member 18 provides support to the in-fill member 20.

The member 20 is made deliberately large enough to ensure that even when it drops below the lower surface 36 of the rigid member 18; it will still extend between the surface 28 of the member 18 and the inner surfaoe 22 of the wall 14. In this way, a seal is guaranteed between the walls 12 and 14 across the cavity of 16.

Unlike the prior art polythene sleeve arrangements, only a small portion of the cavity 16 is spanned by the polythene sleeve and mineral wool arrangement. This allows the arrangement to be fully supported by the rigid member 18, and thus reduces the possibility of the in-fill member 20 being dislodged and falling down the cavity 16.

Reference is now made to Figure 1(b) and 1(c) of the drawings.

Each Figure has been given the same reference numerals as Figure 1(a) to aid clarity. Figure 1W) demonstrates the barrier 10 now located in a cavity 16 whIch is 60 mm across. The cavity 16 may have been designed to be 60 mm. Alternatively the cavity may have expanded after construction is complete by movement of either wall 1214. In this Figure, it is seen that the in-fill member 20, has now been extended across a larger portion of the gap 16 being a distance of 35mm over the cavity gap 16. The in-fill member 20 is still in partially compressed state to ensure that the seal is maintained between the surface 32 of the member and the inner surface 22 of the wall 14.

Turning now to Figure 1(c), the cavity is reduced to 40 mm in width. The rigid member 18 now extends over a majority of the cavity gap 16. in-fill member 20 is in a highly compressed state were a majority of the member 20 lies below the lower surface 36 of the rigid member 18. However, in-fill member 20 still remains attached to the rigid member 18 at the surface 28. There is also a larger contact area between the surface of the polythene sleeve 32, and the inner surface 22 of the wall 14.

Reference is now made to Figure 2 of the drawings which iiiustrates a cavity barrier, generally indicated by reference numeral 110, according to a second embodiment of the present invention. Like parts to those of Figure 1 have been given the same reference numeral with the addition of 100 to aid clarity.

Barrier 110 comprises a rigid member 118 with identical properties to rigid member 18 of Figure 1. in this embodiment, rigid member on 118 is slightly wider, at 35 mm, to project across the majority of a cavity gap 116 which is designed as 50 mm. The in-fill member 120 is an intumescent paint 40 applied to the distal surface 128 of the rigid member 118. As is known in the art, the intumescent paint will expand when subjected to heat. in this embodiment, the barrier 110 does not provide a seal across the cavity 116 in normal use. In this way, moisture falling from the inner surface 126 of the timber frame along the sloped upper surface 130 of the member 118 can drain down the cavity through the gap 42 left between the in-fill member 120 and the inner surface 122 of the wall 14.

In the event of a fire, if sufficient heat reaches the barrier the intumescent paint 40 will begin to expand and fill the gap 42 between the rigid member 118 and the wall 114. A fire barrier is thus provided at the desired time.

Figures 2(b) and 2(c) again shcw variations for wider cavities.

This embodiment is well suited to narrow cavities such as that shown in Figure 2(c), at 40 mm, wherein the intumescent paint 40 is only expected to expand by a short distance, in this case 5 mm to bridge the gap 42 and create a seal. Thus in this arrangement the seal is created in a faster timescale.

In Figure 2W) the intumescent paint 40 is of a highly expanding nature so that it will be sufficient to bridge the wider gap 40 of 50 mm.

Referring now to Figure 3 of the drawings there is illustrated a further embodiment of the present invention. This shows a cavity barrier, generally indicated by reference numeral 210. Like parts to of those of Figure 1 have been given the same reference numeral with the addition of 200 to aid clarity.

Referring to Figure 3(a) of the drawings there is illustrated a barrier 210 including a rigid member 218 and an in-fill member 220. The rigid member 218 is designed in an identical manner to the rigid members 18, 118 in the earlier figures. More particularly, in this figure a distal surface 228 is now in a shaped configuration. Surface 228 provides a channel 46 bounded by upper 48 and lower 50 sills. Channel 46 can easily be machined from a piece of solid timber and the member 218 is mounted on the wall 212 to as described previously.

In this embodiment, the in-f ill member 220 is not conneoted directly to the rigid member 218. The in-fill member 220 is a flat plate of steel sized to locate between the bricks 52,54 in the mortar layer 56 of the masonry wall 214. Member220 is S inserted during construction of the wall 214 and is provided in a location wherein a portion of the member 220 is supported by the wall 214 while a protruding portion 58 extends into the cavity 216 to abut the inner surface 60 of the channel 46 in the rigid member 218.

As the rigid member 218 is treated with a water repellent, the member 218 will not suffer from shrinkage and thus a seal occurs between the surface 60 of the member to 18 and the end 58 of the member 220. Additionally, the channel 46 is machined across a majority of the length of the surfaced 228 of the member 218 so that a sufficient tolerance is left to match a potential brick height at the wall 214. This achieves a mortar line 56 opposite the channel 46. This arrangement provides a fully adjustable in-fill member to 220, which can be positioned during construction of the wail 214.

Referring now to Figure 3(c), the same arrangement is shown for a wider cavity 216. In this arrangement, a majority of the member 220 is located in the cavity 216 with the end 58 still meeting the surface 60 of the channel 46.

Figure 3(c) illustrates the same arrangement for a narrow cavity gap 216, where it is seen that the member 218 now extends over a majority of the cavity 216. While the member 220 is described as being a steel plate, member 220 may be formed from a timber section which is fire treated. Such a timber may be a stiffened timber called rrFireboardrr as is known in the art. One requirement for the member 220 being made of a differing material is to remember that the thickness must not exceed the height of a standard mortar joint 56.

Referring now to Figure 4 of the drawings there is illustrated a yet further embodiment of the present invention. In Figure 4(a) cavity barrier 310 is iiiustrated for use between a masonry wail 314 and timber wall 312. Again like parts in the drawing to those of Figure 1 have been given the same reference numeral with the addition of 300 to aid clarity. In this embodiment, the rigid member 318 is as described for the rigid member 18, 118 of Figures 1 and 2. However, the in-fill member 220 is now a masonry brick.

In construction, the timber wall 312 is erected with the rigid member 318 attached to the surface 326 of the wall 312, as described herein before. To create the cavity 316, the masonry wall 314 is constructed at a distance from the timber frame wall 312. In the example, shown in figure 4(a), this distance is 50 mm. The rigid member 318 has a width of 30 mm across cavity 316.

When the masonry wall reaches a brick height at or near the rigid member 318 the in-fill member, brick 220, is located upon the uppermost brick 354 and mortared 356 in place, such that the inner surface 62 of the brick 220meets the inner surface 328 of the rigid member 318. A facing brick 64 is cut and located behind the in-fill member 320, and the wall 314 is continued by locating a further brick 352 upon the in-fill member 220 and the facing brick 64. As the in-fill member 320 is mortared into wall 314 and abuts the rigid member 318 at its surface 328, a seal is created across the cavity 316.

FIgure 4(b) illustrates the same arrangement. The in-fill member 320 remains the same size of brick and the facing brick 64 is of a wider dimension. In this way, a majority of the in-fill member 320 protrudes from the inner surface 322 of the masonry wali 314 into the cavity 316. The member 320 remains stable as it is mortared 356 into the wail 314 both from below 66 and above 68.

Referring now to Figure 5 of the drawings there is illustrated a further embodiment of the present invention. This shows a cavity barrier, generally indicated by reference numeral 410. Like parts to of those of Figure 1 have been given the same reference numeral with the addition of 400 to aid clarity.

Barrier 410 closely resembles the cavity barrier 10, having a rigid member 418 with run-off 430 together with a mineral wool filled polythene sleeve 420. In this embodiment the sleeve 420 is attached to a flange 70 as is known in the art. The flange is attached to an upper surface 72 of the member 418. The adjustable member 420 is then supported on the surface 430 and again, is required to fill only a narrow gap, created between the rigid member 418 and the wail 412. This embodiment provides an easier method of affixing the mineral wool sock 420 to the rigid member 418.

Referring now to Figure 6 of the drawings there is illustrated a further embodiment of the present invention. This shows a cavity barrier, generaily indicated by reference numeral 510. Like parts to of those of Figure 1 have been given the same reference numeral with the addition of 500 to aid clarity.

Like the rigid member 218, rigid member 518 has a distal surface 528 in a shaped configuration. Surface 528 provides a channel 546 bounded by upper 548 and lower 550 sills. Channel 546 can easily be machined from a piece of solid timber and the member 518 is mounted on the wall 512 as described previously. Tn-fill member 520 is a length of mineral wool covered in a polythene sleeve as described previously. The member 520 is inserted into the channel 546, which is sized to be a snug fit, and held by typical fixing means i.e. nails. When the second wall 512 is constructed the in-fill member 520 is compressed against the surface 526 to provide a seal. It is noted that the in-fill member 520 is sized such that it can naturally droop, while both being supported by the rigid member 518 and maintaining contact with the second wail 512.

Referring now to Figure 7 of the drawings, there is illustrated a party wall joint, generally indicated by reference numeral 80.

Like parts to Figure 1 have been given the same reference numeral with the addition of 600 to aid clarity. In this arrangement, two walls meet providing a T junction. A cavity 616 extends between the walls and across the junction 80.

Accordingly a cavity barrier 510 is located in each leg of the junction 80 to prevent smoke, heat and fire spread across the junction 80. Barriers 510 are Illustrated for example only, being mounted as described previously. It is noted that barrier SlOb is machined differently so that the channel 546 is now directed downwards. Such an arrangement positions the in-fill member 520 against the first wall 614a and thus allows longer strips of mineral wool to be used without expecting the wool to be entirely compressed in the space between the rigid member 518 and the first wall 612b.

Referring now to Figures 8(a) and (b) of the drawings there is illustrated further embodiments of the present invention. These show a cavity barrier, generally indicated by reference numeral 710. Like parts to of those of Figure 1 have been given the same reference numeral with the addition of 700 to aid clarity.

S Like the rigid members 218,518 rigid member 718 has a distal surface 728 in a shaped configuration. Surface 728 provides a channel 746 bounded by upper 748 and lower 750 sills. Channel 746 can easily be machined from a piece of solid timber and the member 718 is mounted on the wall 712 as described previously.

In-fill member 720 is an intumescent material. The member 720 is inserted into the channel 746. In Figure 8(a), the in-fill member 720 is located deep inside the channel 746 such that its outer surface 90 is set back from the surface 728 of the rigid member, inside the channel 746. In this arrangement the intumescent material 720 is protected by the overhang 92 of the sill 748. Figure 8(b) illustrates the intumescent material 720 filling the channel 746. The surface 90 now lies with the surface 728 and the material 720 is protected by the timber of the rigid member 718.

A principle advantage of the present invention is that it provides a cavity barrier which is more rigid and less prone to loosening and collapse than the cavity barriers of the prior art.

A further advantage of at least one embodiment of the present invention is that it provides a cavity barrier having the benefits of a timber batten while also providing the flexibility of the polythene sleeved mineral wool sock without having the disadvantages of either approach.

Modifications may be made to the invention herein described without departing from the scope thereof. For example, while the rigid member has been described as a solid timber batten the member may be made of other fire resistant materials. However, S it must maintain its rigidity in order to support the in-fill member! which may be flexible. Additionally, while the in-fill member is described as being formed of steel or timber/board for the embodiment where the member locates within the masonry wall, it will be appreciated that resilient rubber may also be used.

Other known materials such as wire reinforced mineral wool, calcium silicate, cement based or gypsum based members.

E!urther while the descriptions and diagrams have been shown with an inner timber frame wall being the first wall and the second wall being formed from a masonry wall, it will be appreciated that many of the embodiments may apply to timber frame party walls wherein both the first and second walls are of timber construction.

Claims

CLAIMS1. A cavity barrier for use in a cavity gap between first and second walls of a building construction, the barrier S comprising: a rigid member for fixing to the first wall and arranged to extend across a portion of the gap; and an in-till member for bridging the remaining portion of the gap between the rigid member and the second wall, the in-fill member being adjustable to ensure the barrier spans the gap.
2. A cavity barrier according to claim 1 wherein, the in-fill member comprises a flexible material.
3. A cavity barrier according to claim 1 or claim 2 wherein, the in-fill member comprises a compressible material.4. A cavity barrier according to any preceding claim wherein, the rigid member is a timber batten.3. A cavity barrier according to any preceding claim wherein, the rigid member includes fixing means to affix the member to the first wall.
4. A cavity barrier according to any preceding claim wherein, the rigid member has a width in a range of 20 to 35 mm to extend a significant distance across the cavity.
5. A cavity barrier according to claim 4 wherein, the rigid member has a width of 25 mm.
6. A cavity barrier according to any preceding claim wherein, an upper surface of the rigid member is at a tilt angle with respect to the first wall.

S
7. A cavity barrier according to any preceding claim wherein, the rigid member includes a channel.
8. A cavity barrier according to any preceding claim wherein, the rigid member is treated with a water repellent.
9. A cavity barrier according to any preceding claim wherein, the rigid member is treated with an insect and fungi preservative.
10. A cavity barrier according to any preceding claim wherein, the rigid member is treated with a fire retardant.
Ii. A cavity barrier according to any preceding claim wherein, the in-fill member comprises a fire resistant material.
12. A cavity barrier according to any preceding claim wherein, the in-fill member comprises an intumescent material.
13. A cavity barrier according to any one of claims I to 11 wherein, the in-fill member comprises a length of mineral wool contained within a polythene sleeve.