BUILDING FABRIC 25
AVOIDING PITFALLS FROM ROOFS
Marley’s Stuart Nicholson pinpoints the most common roof specification pitfalls, and advises housebuilders on how to avoid them for a best practice approach.
decade – with the introduction of more stringent British Standards, masses of new product innovations, and the development of single-source roof systems. However, with ongoing reforms to the building safety regulatory system and increasing focus on accountability in the housebuilding sector, more needs to be done to make sure that the BS 5534- compliant roofs that are being specified end up on the finished property. Roofing experts often get called out to investigate issues with newly constructed pitched roofs. Some of the problems seen include condensation caused by lack of ventilation, leaks, non-compliance with British Standards, incompatible dry fix systems, insufficient fixings for the level of exposure, tiles being used below minimum pitch, and health and safety risks from inferior battens. Often these issues are caused because there has been a change in the specifica- tion between the design and construction phase, or because inferior or incompatible products have been used further down the supply chain. This potential gap between design and
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actual built performance continues to be a concern and, to reduce risk, there needs to be a shift towards more robust roofing specifications that consider the impact of the full roof system, not just the tiles. This means that little is left to chance or value engineering, and housebuilders have more control over the quality and safety of the whole roof.
MORE NEEDS TO BE DONE TO MAKE SURE THAT THE BS 5534-COMPLIANT ROOFS THAT ARE BEING SPECIFIED END UP ON THE FINISHED PROPERTY
he quality and security of pitched roofing in housing has seen some huge improvements over the last
Below are some of the most common
roof specification pitfalls and how to avoid them.
RE-USING SPECIFICATIONS It is quite common for roof specifications to be re-used, but it can’t be stressed enough how important it is to create a new roof system specification for every project to avoid risks to liability, and keep pace with product advancements and changes in standards.
NOT CONSIDERING THE MINIMUM PITCH OF A ROOF TILE The minimum pitch that a roof tile can be used at can vary greatly depending on type of tile and the length of the rafters being used. This needs to be considered in the original specification, or it could lead to problems with weather tightness further down the line.
ALLOWING TOO MUCH SCOPE FOR PRODUCT CHOICE Specifying the roof covering but leaving the choice of dry fix systems and other components to roofing contractors means housebuilders are losing control over some of the most important structural and weatherproofing parts of a roof. This could lead to value engineering, or the use of generic products that may not be compatible with the specified tiles. The best way to avoid this is to specify
a full pitched roof system from one manufacturer, which reduces this risk and guarantees compatibility and compliance.
SPECIFYING A GENERIC ROOFING BATTEN This is one of the biggest areas of concern. All roofing battens should meet BS 5534 grading criteria, which allows them to be used as a secure foothold during installation. Unfortunately this
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