Hidden Heroes; Unassuming cavity barriers can be the most important
Last updated September 14th, 2022
Hidden Heroes; How the most unassuming of construction materials, such as cavity barriers can be the most important. Why cavity closers and fire cavity barriers should get your undivided attention in specification
‘Everything should be made as simple as possible, but not simpler.’
Hidden Heroes; There are things in life we take completely for granted and yet make life possible, or should I say, their failure can make life very uncomfortable.
Here’s a good exercise on a rainy January Sunday afternoon. Think about how much our lives depend on a handful of unexciting objects that rarely get our attention. You may note things like the right size spanner, a Philips head screwdriver or that one allen key you need to dismantle an IKEA chest of drawers. Particularly emotional examples include the right size batteries for that toy on Christmas morning, or, if you’ve been unlucky enough to experience it, the central heating pump that fails on Christmas Eve.
My personal favourite is the much-needed 13A fuse that I can’t find in the kitchen drawer.
Such a small, unassuming, quite boring object. But if you stop and think about fuses in general, you realise that our civilisation is literally built on them. They are everywhere, (including other versions such as miniature circuit breakers). Without them, we can find ourselves without the TV, the kettle or computer. Far more importantly, they protect our appliances from overload and destruction, or in the extreme, prevent fires and loss of life and property. And yet such essential protection comes incredibly cheap- you can buy a pack of four 13A fuses for £1.10 at your local hardware or DIY store.
We often behave in a similar way when specifying materials on a project. It is human nature to focus on products that make a ‘big impact’ visually and work together in harmony to reach the elusive goal of creating architecture rather than building. But this cannot be at the expense of rational and careful use of the correct materials. It can be the difference between a successful building and a failure. More critically, it can even mean the difference between health and mortality.
Roman architect, civil and military engineer Marcus Vitruvius Pollio, worked during the reign of Emperor Augustus and served under Marcus Agrippa (after whom is named The Pantheon in Rome). He is well known to this day for his genius thesis known as the ‘Vitruvian Triad’, a beautifully simple idea comprising three Latin words: firmitatis, utilitatis, and venustatis. These defined the essential qualities he believed every structure should possess and translate as Commodity, Firmness and Delight.
Commodity – careful design of spaces and accommodation i.e. good planning.
Firmness – Stability and quality of construction i.e. correct in detail and materials.
Delight – Beauty and timeless quality.
It is the quality of firmness that concerns us here. Ensuring that the materials chosen and detailed receive the appropriate attention and care. As the 20th Century German architect Ludwig Mies Van Der Rohe famously observed, ‘God is in the detail’.
The Hidden Heroes: Cavity Closers and Fire Cavity Barriers
*Richmond House – 23-flat building in the Worcester Park development in south-west London.- Inside Housing 09/09/20
“There was no effective obstacle to prevent fire spreading into the roof, which there should have been,” the report said.
The above inferno in a low-rise apartment building was the result of the absence of cavity barriers. This meant there was nothing to prevent spread into the roof and wholesale destruction of the building. Thankfully no lives were lost, but possessions were destroyed, and lives disrupted.
What are cavity closers and fire cavity barriers?
Cavity closers are insulated profiles closing off the cavity at reveals, acting as a DPC. They are used with standard brick construction, timber frame and other constructions.
Fire cavity barriers are defined in Part B of the Building Regulations as “A construction, other than a smoke curtain, provided to close a concealed space against penetration of smoke or flame, or provided to restrict the movement of smoke or flame within such a space”.
The most tragic example of such failure, of which everyone is aware is Grenfell Tower. One of the findings was that no cavity barriers had been installed. Part B of the building regulation clearly states that different compartments should be separated by fire cavity barriers. But this wasn’t the case with Grenfell. Fire penetrated the cavity and was drawn up the building. There was nothing to stop it at each floor and apartment.
Therefore, it is critically important that proper attention is paid to ensure the correct specification and detail. Because such failure cannot be allowed. Cavity closers and barriers are inexpensive, effective and highly functional. Once installed, these modest objects will carry on protecting the building and its occupants for decades without failure. They deserve our profound respect and attention for the heroic qualities they possess.
The carrier is made from part recycled uPVC and can be 100% recycled at end of its life, whilst the mineral wool insulant is noncombustible and nonpolluting. They also require zero maintenance during the lifetime of the building, but we do advise that cavity closers be replaced if or when new windows are installed. This also allows for any increase in thermal efficiency to meet new standards with newer technology.
As with any simple product, the application can be a little more complex. Getting the right ‘fit’ is essential, and we are happy to advise with the optimal use of product for your project. Please see our contact details below.
We also have an RIBA assessed CPD that covers all the essentials when considering these products:
It is titled ‘Saving energy, protecting life, health and property’, because put simply, that is exactly what they do.
William Golding was quite correct; the greatest ideas are the simplest.
Article written by Paul Iddon ARB RIBA, Vice-Chair Manchester Architects, Managing Direct PSI
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