Could Rapid Build Housing mean Rapid Fire Spread? | Michael Tweed B.A. B.Arch RIBA MRIAI

Fire

09 August 2016

I’m worried!

A specific objective of the government’s housing plan is to meet the needs of homeless families by expanding the Rapid Build Housing programme to provide 1,500 units. Terminology used for the sole purpose of disguising actuality annoys me intensely and it seems to me the term “rapid build” as a description for timber frame houses is just such a term. Let’s call a spade a spade, rapid build houses are actually timber frame houses. And that’s what has me so worried.

My concerns over timber frame construction were first raised about 18 months ago when a colleague asked me to help advise on remedial works to a pair of semi-detached houses following a fire. This was a pair of timber frame houses with a timber party wall either side of a blockwork chimney stack. Luckily, and take my word for it this was pure luck, the fire which had started in the party wall was put out just in time to prevent catastrophic collapse of both first floors. As is was there was severe damage to the timber party wall and the floor joists. The solution we proposed and which was adopted was complete rebuilding of the party wall in blockwork.

In this case the fire had occurred following installation of a stove in the living room fireplace of one of the houses. To make the stove fit it was evident that the brick chimney breast had been altered, decreasing the thickness of the chimney breast walls locally in one spot. The extra heat produced by the stove over a traditional fire, coupled with the reduced thickness of the chimney wall apparently caused the timber party wall structure to smoulder unseen in the cavity between the two houses. After smouldering for some time the timber caught fire and it was only the ingress of smoke into a bedroom that alerted the owner of the house that the wall was on fire.

Thankfully, and I reiterate luckily, the occupants of both houses escaped unscathed. But it could easily have been much worse, with greater collapse to the structures or actual loss of life!

Then in the course of my research around fire risk and fire precautions for timber frame construction I came across a very worrying online article on the BBC New website (Link: Here). The gist of the article was that a 1999 test carried out by the Building Research Establishment (BRE) on a six-storey timber framed building in the controlled conditions of an aircraft hangar gave sufficient justification for the UK to relax old regulations prohibiting the use of timber frame houses. However, the BBC report points out that what wasn’t reported by the BRE was that in the early hours of the morning after the test the fire reignited and by the time firefighters returned to the hangar the top 4 floors were completely burned out. The similarity between the two incidents, where smouldering timber eventually ignited seems to me obvious. Any quick search of Google will produce lists of reports of significant fires in timber frame buildings.

A few months later, while working on house fire project, a fire occurred in a terraced timber framed house at Millfield Manor in Newbridge during April, 2015. It came as no surprise to me to learn that the fire had rapidly spread along the terrace completely destroying several of the houses. I thought perhaps the speed of the spread of fire, and vivid illustration of what had occurred summed up in the aftermath pictures showing some brickwork walls and most eerily of all the brick chimney stacks as the only things left standing would have given rise to widespread concern over the safety of timber frame construction.

But apart from a few voices crying in the wilderness, such as Mick Clifford, there’s nothing. Here we are now with our government endorsing the construction of 1500 timber frame houses! The Newbridge fire wasn’t the first such incident of rapid spread of fire in timber frame terraced houses either. In April, 2011 a fire occurred in a terrace of timber frame houses in Terenure with almost identical consequences and rapid spread of the fire from house to house. Perhaps it’s the cynic in me that believes no one will call stop until fatalities have occurred. (LINK: Here)

Is it that the government doesn’t want to look into these matters too closely? Were the Local Authority financial costs (let alone the personal costs to the owners and occupants) of Priory Hall on their minds as they contemplated the can of worms a full scale nationwide survey of the existing stock of timber frame houses might open? But what about the risk of not doing anything. Like the Stardust disaster, do we have to wait until lives are lost before something is done?

When timber framing is used for separating structures such as party walls or party floors the element of structure is a combustible material – timber. Fire separation relies entirely on the application of fire resisting materials (plasterboard and usually rockwool fire-bats) to either clad the timber or fire-stop cavities in the construction. Detailing the fire separation of timber party structures is complex hence construction is complex. Complexity requires greater vigilance to ensure the construction is correct every time. Because the elements of structure are timber the fire protection must be 100% every time. There is no room for error!

But as the incident which brought timber frame construction to my attention showed it was something which happened after construction which led to the fire. Now consider, the only thing stopping spread of fire from one house to another is 25 – 30mm (that’s one inch!) of plasterboard either side of the wall. What about the unwitting occupant who doesn’t appreciate the nature of his party wall and the consequences of interfering with it, who thinks this is simply another dry-lined wall? Suppose heavy duty bookshelves, or a heavy plasma TV are fixed to the party wall? As holes are merrily drilled through the plasterboard the integrity of the fire resistance is surely diminishing with each hole.

And now let’s face the real truth about the Irish Building Control system since its introduction in 1992. The system of self-certification introduced then has been deeply flawed. All the timber framed houses have been built under this control regime. No Local Authority Fire Safety Certificates are required for fire design in houses. Up until 2014 compliance was indicated by an Architect’s Opinion on Compliance based on a visual inspection only.

Finally no one, and I believe most particularly our government, should be under any illusion that new regulations since 2014 (SI. 9 ) have improved the situation. As I’ve stated before it’s simply self-regulation with added paperwork!

Other posts of interest:

Fire Risk and Attic Conversions | Michael Tweed

One ‘L’ of a battle looming over DECLG Building Regulations | Michael Tweed

Fire Trap Home Buyers Beware | Still No Consumer Remedy

Fire Safety in Green, PassivHaus and Energy Smart Housing | CJ Walsh

Michael Clifford: “when will we address cracks in construction?” Irish Examiner

You can still buy a non-compliant home…and it’s all perfectly legal | SI.9 Loopholes

Is the scene set for another Priory Hall? | Look Back 11

3 thoughts on “Could Rapid Build Housing mean Rapid Fire Spread? | Michael Tweed B.A. B.Arch RIBA MRIAI

  1. Michael O'Neill

    I totally endorse the comments of the writer Michael Tweed.

    I believe that the only way you could be certain of separating walls in houses fulfilling their function as a fire and sound break (sound is another issue with lightweight drywall timber frame construction) is to go back to the old rule of thumb detail which I seem to recall was shown in the Proposed Building Regulations – the big navy blue book?

    This proposed detail raised solid masonry separating walls 375mm above the highest adjoining outer roof covering between semi-detached and terraced houses. This totally blocks the passage of fire from one property to another where they share this party wall and also prevents fire from licking over the party wall to ignite the felt on the other side.

    In visual terms the top of the party wall is effectively a parapet wall that follows the line of the roof. The wall is corbelled out at the eaves to stop the Eaves Boxing Cavity transmitting cold smoke, fumes, gases or fire.

    Spot checks need to be carried out to ensure the joints are full be and perpend and that the roof junction is correctly detailed and the parapet wall weathered. Additional detailing will be required to address cold bridging but in general this is a secure and robust solution for separating semi-detached and terraced houses.

    Part L worshipers have used concerns about carbon emissions to lay the remedy on the shoulders of homeowners while blithely ignoring the fuel bills of all the world’s armies and to avoid wet trades and promote built up lightweight drywall construction (timber or steel). What price energy savings when you expose the owners/ occupants to significant risk of death or maiming through rapid fire spread, cold smoke and fume transmission and catastrophic collapse?

    These deaths are foreseeable based on the near-tragedies to day which Michael Tweed and I have commented on here. The government has done nothing in real terms to address these foreseeable tragedies and prevent them from happening. Based on this apparent inaction it seems reasonable to assume that the Minister for the Environment and his fellow travelers are either in thrall to unscrupulous developer and builders or else totally incompetent to hold high office.

    The losers here will be the people who will die in house fires, their families, friends and relatives, before anything is done to correct this terrible state of affairs.

    Reply
    1. Brendan Thomas

      I agree completely that a reversion to the old principle of solid separating wall is the simplest and best solution, But should we expect a response? You answered that question already Michael with your ‘reasonable assumption’

      Reply

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