How to take control of roofing specifications

The introduction of another new pitched roofing standard means it’s more important than ever for local authorities to take greater control of roofing specifications. Stuart Nicholson, roof systems director at Marley, explains more……

The durability and security of pitched roofing is coming under increasing scrutiny, with the launch of another new roofing standard. BS 8612: Dry-fixed Ridge, Hip and Verge Systems for Slating and Tiling came into force on 31st January 2018, following concerns about the quality of some cheaper systems. The new British Standard sets minimum performance criteria for dry fix systems for the first time, focussing on areas such as weather resistance, durability and mechanical fixing.

Specifiers may not have considered the quality differences between dry fix systems because as a method it is perceived to be inherently strong and durable, compared to using mortar. However, the increasing popularity of dry fix systems, since major revisions were made to BS 5534 in 2014, has led to a huge increase in the amount of products on the market, with many offered at a much cheaper price and claiming to do more or less the same job.

While they may look broadly similar, the quality and performance of the components used in dry fix systems can vary significantly, with some systems value engineered to bring the cost down. Inconsistencies in durability and weather resistance have even led to some reported product failures, such as ridge tiles not being fixed securely enough and ridge rolls not adhering to the top course of roof tiles properly. Additional problems have been reported of severe staining to gable ends of buildings, with water not draining away from walls due to poorly designed verge units.

Such was the concern about this, that the British Standards Institute developed the new Dry Fix Standard, BS 8612: Dry-fixed Ridge, Hip and Verge Systems for Slating and Tiling. The introduction of BS 8612 should improve consistency and reduce the amount of inferior systems on the market. However, as it is not a legal requirement, specifiers need to make

sure that compliant products are used on their projects. This is particularly important given growing concerns about so called ‘spec busting’ in the construction industry.

The problem of spec busting

‘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, product lead times and increasing pressure on contractors to drive down costs means that product substitution is a particular issue at the moment. The problem is that products which appear to be equal may not be and there can be significant differences in quality, guarantees, weather resistance and environmental performance. Dry fix systems are a good example of this.

Increasingly stringent standards, like BS 8612 and BS 5534, are improving the quality and security of pitched roofing but in order to ensure compliance with these standards, local authorities need to take greater control of specifications and minimise the risk of inferior products being used.

What do specifiers need to do?

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

2. When it comes to dry fix systems, even if you don’t name a specific manufacturer, the specification should state that relevant products used must meet BS 8612 or BBA requirements. This will protect the performance of the roof, as well as liability in the event of any future claim.

3. Update all specifications to ensure compliance with the new standard - don’t delay or presume that all products used will meet the BS 8612 requirements. Marley’s dry fix products, which fall under the scope of the new standard, have been put through rigorous testing to ensure they meet, or exceed, the expectations of the new BS 8612 standard.

4. Consider specifying a full roof system from a trusted manufacturer - including underlay, battens, tiles or slates, fittings and accessories. This is one of the easiest ways to ensure compliance with both BS 5534 and BS 8612 and minimises the risk of unmonitored product choice or substitution.

Specifying our complete pitched roof system gives peace of mind that all elements comply with British Standards, and can be backed with a 15 year system guarantee.

5. Be aware of changes to dry verge fixing. Under BS 8612, dry verge products can no longer be installed just with a nail fixing into the end grain of the batten. Instead, mechanical engagement must be on the faces of the batten. There are specific products available on the market to help with this, such as our new Batten End Clip.

6. If you want more information about roofing standards, you can complete our new British Standards CPD, which has been updated to include BS 8612, as well as BS 5534 and BS 5250.