Prevent roofing defects

Prevent roofing defects

To build more homes with fewer complaints from customers what is needed is competence, technical knowledge and experience – and these do exist, if you know where to look, says David Patrick, Head of Marketing at Redland.

A 2015 survey by the Home Builders Federation and the National House Building Council (NHBC) revealed that 93% of buyers report problems to their builders, with 35% of these finding eleven or more issues.

The problem of excessive defects, and how to prevent even more occurring if we build more houses each year, was the subject of investigation by the All Party Parliamentary Group for Excellence in the Built Environment. It published a 44-page report on the matter, More Homes, Fewer Complaints, in July 2016.

There’s certainly no silver bullet. The report makes several recommendations, many of them related to regulation but it doesn’t address the elephant in the room: modern procurement methods mean homes are built by a disparate collection of contractors, sub-subcontractors and their suppliers. Far more could be done to harness the knowledge and technical capability of those who supply the materials and products that make up a home.

Long time coming

We could look back thirty years to see the beginnings of this way of working when Sir Stuart Lipton and Peter Rogers were developing Broadgate near London’s Liverpool Street Station. They came up with a new way of procuring buildings: rather than having a main contractor build everything with a directly-employed workforce, they split the building works up into packages with the main contractor overseeing lots of specialist contractors.

The 1980s also saw the design-build form of procurement start to take hold, where the builder takes an outline design and performance specification and carries out the detailed design himself. Critics of this form of contract translate this approach as giving carte blanche to seek out the cheapest possible products and materials that will just meet the required criteria.

Changes in contract forms also saw the disappearance on many house building sites of an important character: the Clerk of Works. Traditionally employed to look after the client’s interest, the role of the Clerk of Works was to generally make a nuisance of themselves by being a stickler for detail.

Today it is more often than not the time-pressed site manager who assumes that role on a housing site. And if you talk to professional snagging firms – which started to appear in the early 2000s as defects in new homes rose – the one thing that impacts on the number of defects in a new property is the calibre of the site manager.

Main defects

NHBC ‘s latest statistics about claims made by new home owners related to 2014*, when there were 7,100 valid claims made equating to around 6 claims per 1,000 homes. This was lower in both total number and frequency than for 2013.

However, the NHBC’s annual accounts show that its bill for claims paid out rose in 2014/15 to £87m, up from £79m in 2013/14. There is a caveat here, however, in that storm damage was a big contributor in 2014/15.

Though the total number of claims was down, the number of valid claims made in the first two years rose in 2015. The biggest problem area was services, fixtures and fittings, accounting for 37% of claims, followed by superstructure 35%, roofs 12% and ancillary buildings and external works 11%.

The most common cause of superstructure claims in the first two years is problems with doors and windows, followed by DPCs and cavity trays, brick and blockwork, render and chipboard flooring.

Claims made in years three to 10 of NHBC warranty cover are dominated by two elements: roofing and superstructure. In 2014, these accounted for 55% and 37% of all claims by number respectively. Regionally however, the picture varies somewhat with roofs accounting for 58% of claims in England and Wales, 39% in Scotland and 28% in Northern Ireland.

Roofing claims

Over 50% of roofing claims related to problems with mortar. This is an issue which NHBC has been tackling since 2011 when it reported that 60% of all its claims in 2010 had related to pitched roofs and over half of those were due to mortar. And this, of course, culminated in the most recent revisions of CP 142, now enshrined in BS 5534: 2014, the Code of Practice for Slating and Tiling in the UK.

In 2010, the NHBC had spent £11m on roofing claims and estimated that the total cost could be at least £30m when adding in repairs undertaken directly by builders. NHBC does not reveal the current cost of pitched roof claims, although it has said that the awareness and information campaign it has been conducting has not yet led to a reduction in claims.

Although not legally mandatory, compliance with BS 5534: 2014 is considered not only best practice, but also provides the best defence in the event of failures or disputes. The NHBC is especially vigilant in respect of the standard and, since July 2015, all new housing projects, regardless of size or phase; must comply with BS 5534: 2014 to qualify for its 10 year Buildmark Warranty.

“Far more could be done to harness the knowledge and technical capability of those who supply the materials and products that make up a home.”

In 2015, statistics on claims revealed some areas of growing concern around workmanship and pitched roofs: 14% of claims related to flashings and upstands at abutments and 9% were connected to projections through roofs such as roof lights or dormer windows.

When it comes to the superstructure of the house, the primary trigger for external wall claims in the longer term was damp penetration which had been caused by badly fitted cavity trays and render failure. In fact, half of all claims were due to problems with cavity trays or DPCs. Chimneys and flues were also a common source of claim.

One of the messages to emerge from the various guidance notes issued by NHBC is that sometimes there can be conflicts between different sources of regulation: British Standards, Building Regulations and the NHBC’s own standards. For the inexperienced site manager, the picture can be confusing.

What this tells us is that there is no substitute for experience and competency: in those running sites, in the specialist contractors installing the various elements and in the suppliers who, if reputable, will have technical experts who are au fait with the plethora of regulations.

The More Homes, Fewer Complaints report makes two recommendations around issues of quality and workmanship: that housebuilders should adopt a new quality culture and that the industry should significantly increase skills training programmes.

These are both areas in which suppliers can offer expertise, advice and training. More communication and information flow up and down the supply chain is the only way to banish problems with defects forever.

*NHBC’s 2015 homebuyer claims data will be available early 2017.

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