Roofing, Cladding & Insulation

PREVENTING THE SPREAD OF ROOF FIRES IN TERRACED AND SEMIDETACHED HOUSING

With recent reports raising concerns about inadequate fire barriers in the roofs of some newbuild homes, Stuart Nicholson, Roof Systems Director at Marley, says all social housing providers should review fire stopping specifications.

Fire barriers are an unseen, but very important, product when installing a pitched roof on terraced or semidetached housing. When a roof is compartmentalised, fire stopping is required between the top of the party wall and the roofcovering, acting as a seal to prevent spread of flames and smoke between properties in case of fire.

However, there have been some house fires in recent years where the fire has spread across the line of the party wall and caused damage to neighbouring properties. This issue of fire spreading in roof voids was addressed in separate reports from the BRE and BBC Watchdog, which raised concerns that some modern homes could have inadequate, incorrectly installed and, in some cases, no fire barriers at all. In fact, investigations found that 650 new homes in one region of the UK had missing, or incorrectly installed, fire barriers.

Whilst the research took place in private new builds, it is equally concerning for the social housing sector, which has a large proportion of terraced and semi-detached homes, multiple occupancy buildings and flats (which also require fire breaks in the roof). Clearly, any home without fire stopping is in breach of the Building Regulations and this is very worrying. However, the fact that, in some cases, fire barriers had been installed but they may not have worked effectively, is just as troubling.

Unfortunately, there are a few reasons why a fire barrier could end up being inadequate or incorrectly installed. Fire stopping is often achieved with a flexible mineral fibre quilt or sock, but a potential fire passage still exists at the line of the roofing battens, above the rafters, which can span across the junction between properties. In addition, standard details, such as spandrel panels in timber frame construction, may be used to satisfy fire separating requirements but don’t provide fire stopping to the underside of the roofcovering.

There are fire barrier products available on the market to close this gap but feedback from contractors suggests that these can be bulky and difficult to install in line with the roof tiles, especially with deep-profiled tiles.

It is also difficult to see if the fire protection is in the correct place once the tiles have been laid. This means there is a risk that social housing providers have specified a fire barrier and it is present, but it may not be installed correctly, or might not be sufficient to fully seal the gap.

What can social housing providers do to reduce risk?

1. Ensure fire stopping is specified in line with Part B of the Building Regulations

Approved Document Part B provides guidance on specifying and providing compartmentation within the roof.

2. Take more control of fire barrier specification

Give careful consideration to fire stopping in the roof of semi-detached and terraced housing, as well as fire breaking in blocks of flats. Provide specific detailing and a named product, don’t leave it open to interpretation by non-specialist contractors.

3. Specify an easy-to-install intumescent fire barrier, that can fill all gaps in case of fire

To give social housing specifiers peace of mind, we have launched our new Marley Roof Defence fire barrier. It is simple to install, which gives confidence that it is correctly fitted and will provide full fire protection, from one roof to the next, achieving up to a 60-minute fire rating.

The Roof Defence fire barrier features two strips of intumescent material bonded at 90°, with an inverted T design, that can simply be installed under tiles and between roof battens to close all gaps in the event of fire. Whereas some other systems are rigid, Roof Defence is flexible, lightweight and is supplied on a roll, so it can easily be taken onto a roof and rolled out over the party wall.

When activated by heat, the inverted T intumescent seal expands, filling the space between roofing battens and sealing all spaces under the tiles, slates, and other roofing elements. It has outperformed all fire testing requirements and fills every void from the party wall to the bottom tile, meaning smoke and fire cannot pass through.

Roof Defence can also be specified as a comprehensive fire barrier in larger roofs, or as a fire break in expansive buildings with large footprints such as apartment blocks, schools, care homes, offices and hospitals.

4. Consider specifying a full-pitched roof system with a fire barrier included

For ultimate peace of mind, social housing providers can specify a full Marley roof system, including JB Red battens, underlay, tiles or slates, fixings, accessories, Roof Defence fire barrier and optional solar PV, backed up by our 15-year warranty. This ensures that every roof on every property is fully compatible and compliant with all regulations, as well as reducing the risk of product substitution.  www.marley.co.uk/roofdefence