Guaranteed results

Mark Parsons of Russell Roof Tiles explains how, in the light of challenges posed to NHBC guarantees by roofing, a pick and mix approach to specification isn’t always the best option.

With more and more new homes being built, it is essential that there is a focus on constructing properties are constructed to a high specification. Raising standards is one of the cornerstones of the National House Building Council (NHBC), the UK’s leading standard-setting body and provider of warranty and insurance for new homes. The NHBC is supporting builders, both large and small, to improve quality for buyers.

The latest housing statistics from the NHBC New Home Statistics Annual Review showed that in 2015, 75 per cent more new homes were registered than in 2009. In total 156,140 new homes were registered – representing an eightyear high in housebuilding. The NHBC also reported in November that post-referendum new home registrations are in line with 2015. This consequently translates into increased sales of building products.

One of the continuing challenges to the NHBC and its Buildmark cover (a 10-year guarantee against structural damage to certain parts of the home) is roofing defects. In 2015 roofing accounted for 12 per cent of claims in the first two years and 55 per cent of all claims in years three to 10.

Roofing contractors are often disproportionately blamed for many of these problems. In fact, it is estimated that only about 25-30 per cent of the problems are workmanship-based, and much of the remaining 70-75 per cent can be designed out by the correct detailing, better coordination of the trades (e.g. fascia board heights), or the use of dry-fix systems.

In Britain, we’re experiencing an overwhelming change in climate, especially in the last decade. With winds of over 100 mph being recorded in localised areas of the country there is no room for substandard roofing installation. To reflect these changes, the latest version of BS 5534 British Standard for Slating and Tiling was created. The standard details the mechanical fixing requirements of roof tiles, ridge and hip tiles. Most roof tiles will require an increased number of fixings, with all interlocking tiles requiring a minimum of one fixing, and all perimeter tiles requiring at least two.

The ever-changing British weather is not the only challenge to modern roofing. A mix andmatch approach to products can be problematic.In terms of specification for tiles, accessories and fittings, mismatched products frequently cause problems.

Would you buy a car with a range of different parts, some branded and some not? Using different parts actually designed and manufactured for a completely different make of car? That is the challenge that the roofing industry faces. How can you guarantee the reliability of a product with different components, supplied by different manufacturers, that are expected to work together seamlessly?

Guarantees are essential, giving everyone in the supply chain added reassurance. How can we be confident about building products unless we guarantee them? In law, a guarantee is an agreement given, without any extra charge, to repair, replace or refund on goods which do not meet the specifications set out in the guarantee. A warranty is an insurance policy which provides cover for the unexpected failure or breakdown of goods, usually after the manufacturer or trader’s guarantee has run out.

If we, as members of the construction industry, seriously want to cut down on defective roofs, it is not good practice to mix products. Many leading products are designed and tested for use in combination with each other over many years.

Russell Roof Tiles advises contractors that to achieve the best effect, tiles should be mixed from different batches, normally a minimum of three. This is because while the size, shape and weight of tiles are controlled during the manufacturing, the colour shading is not 100 per cent the same in every batch. The shading can be affected by a number of different factors during the manufacturing process.

Products should be installed using normal standards of good workmanship and meet the requirements of the British Standards for slating and tiling (BS 5534 and BS 8000-Part 6). The substitution of one manufacturer’s components with other products at any stage of construction often invalidates a guarantee.

In the roofing industry, warranties as a whole need to be addressed, both in terms of specification and in the mixing and matching of different manufacturers products – a challenge the industry has to tackle head on, and work closely with the NHBC to overcome.

Mark Parsons is technical director at Russell Roof Tiles.