Take control of roofing specifications

// the building envelope

Phil Wallis, technical manager from Marley Eternit, explains why it is more important than ever for housing associations to protect roofing specifications from product substitution

‘Spec busting’ is the practice of substituting construction products that have originally been specified by the architect, designer or client.  In many cases, a specified brand of product is changed for what is perceived to be an equivalent and is usually done for reasons of cost, availability or preference. 

This issue of spec busting is a concern across the whole construction industry and in the 2017 NBS Specification Report, 57% of specifiers who had problems with specifications said that it was down to materials being substituted. 

When it comes to roofing, the increasing pressure on contractors to drive down costs and ongoing challenges with product lead times, means that product substitution is a particular issue at the moment.  It is therefore important for housing associations to be aware that products which appear to be equal may not be and there can be significant differences in quality, guarantees, weather resistance and environmental performance.

Pitched roofing is an area coming under much greater scrutiny with increasingly stringent British Standards, so housing associations should take greater control of specifications to ensure all elements of a roof stay compliant.  


The first step is to avoid specifying generically by type rather than product name, e.g. roofing batten, as this allows the opportunity for products to be sourced further down the line by contractors involved.

One example of this is with dry fix systems.  Although up until now, they haven’t traditionally been specified by brand, the end of January sees the launch of a new Dry Fix Standard, BS 8612.  This defines minimum performance criteria for dry fix products, following concerns about inconsistencies in quality.  Therefore housing associations will need to make sure that they specify either a particular brand, or state that it must be a BS 8612 compliant dry fix system.

Another way to take more control over roofing specifications is to choose a full pitched roof system from one supplier – including underlay, battens, tiles or slates, fittings and accessories.  This gives maximum control of the supply chain, minimising the risk of unmonitored product choice or substitution. Specifying a complete pitched roof system from Marley Eternit also gives peace of mind that all elements comply with British Standards, and can be backed with a 15 year system guarantee.

For more information, or help with roofing specifications, visit www.marleyeternit.co.uk

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