Part B: We have to get this right

After 23 years in construction I thought I was pretty clued up on the many things that can go wrong in the industry. But I learnt something new last September that not even serving as minister in charge of Building Regulations had prepared me for. The insight came not from a high-powered seminar of construction experts but from a catastrophic fire on a housing estate in my constituency that left three local families homeless and around 60 other families worried about the safety and value of their homes.

These homes were just over 10 years old, built to Part B specification, but three in a row burnt down to the ground. How could it happen? Aren’t there rules about that? Why did the fire spread? Could it happen again? Plenty of good questions from worried residents, and one very puzzled local MP. It shouldn’t happen. And yet it does and it did.

The Fire Brigade and NHBC (who exercised the building control function, and whose guarantee had expired a few months before the fire), the trade association - the Structural Timber Association - and the Local Authority all had views to share. These were timber-framed, brick clad homes, of two and three stories, built in short blocks and terraces. A complete block of three homes was destroyed.  

The big challenge is the same as that which undermines high performance in energy-saving buildings too. That is the human factor

That’s why in parliament’s last weeks before the general election I was pestering ministers and officials about the significant gaps there are in the regulations, and the risks those gaps create. Now the building standards minister Stephen Williams has announced that there is to be a review of Part B to see what, if anything, should be done to tighten things up.

BRE has been commissioned to do some research, and look hard at the evidence. It turns out my local fire is one of a series, with some common features. I’ve certainly reached the conclusion that there are some simple changes that can be made to Part B to avoid those and which I believe could drastically reduce the risk in homes built in the future.

In this case, once high temperatures ignited timber in the cavity, the fire spread vertically to the fire stops at roof level, where flames quickly bypassed the barriers, spread into the roof, and along the block - notwithstanding the fire compartmentation between dwellings. There is no requirement in the regulations for fire stops at each floor level in a single home, so that led to very rapid fire spread through three stories. And the vapour membrane wasn’t just flammable, but, as a video of a Fire Brigade test showed, actually acted as a very effective wick for combustion.

As an older and now rather wiser MP I’ve urged the review to look at requiring fire stops at each floor level in single homes, and for the membrane to be non-flammable.

It isn’t all about tighter rules, though. Certainly they need to be in place, and careful workmanship and good practice are also needed to deliver the correct detailing to avoid fire spread in timber-framed buildings. Safe design can all too easily be undermined by poor installation.

I’ve written before about the need for designers to make today’s high-tech non-traditional house designs more intuitive for occupants. Progress has been painfully slow

However, the big challenge is the same as that which undermines high performance in energy-saving buildings too. That is the human factor. Fire penetration in timber-framed homes is most often triggered by the removal or cutting through of plasterboard designed to be integral to the fire compartmentation. In this case it happened during the course of alterations commissioned by the homeowner. So just as energy performance depends not just on the “as built” structure, but also the “as lived in” building, so too does effective fire resistance. Obvious, of course, but we don’t yet do nearly enough to equip residents with the understanding they need to use the buildings we construct for them.

I’ve written before about the need for designers to make today’s high-tech non-traditional house designs more intuitive for occupants. Progress has been painfully slow, so residents just use their “common sense” and open windows or turn up thermostats to change their environment. And they do just the same, it seems, with conveniently modular timber-framed homes, stripping out walls and refitting as they need, without considering for a second the additional fire risk the man with the blow torch poses as he fits the heating while the plaster is stripped out.

So let’s get the rules and regulations right, let’s carefully build to those rules, and let’s invest much more time in making sure building users have the information and understanding they need to live safely and cheaply in the homes we construct.

Andrew Stunell is stepping down as Lib Dem MP for Hazel Grove this month and is a former minister responsible for Building Regulations