The horrific fire at Grenfell Tower has highlighted the importance of fire safety in new and updated dwellings. And while the shocking events in London were in part down to an unfortunate and tragic combination of quite different factors, as well as the height of the tower itself, it has also raised concerns for those building or renovating their own home about the best ways to ensure this kind of thing doesn’t happen to their individual home.
Clearly the situation in London is going to throw a lot of attention on fire safety elements within Building Regulations and two things are likely to happen:
- Building control inspectors are likely to give more attention than before to fire safety issues and as a result designers need to ensure they come up with satisfactory details;
- The actual Building Regulations are most likely to be amended and improved and as a result designers and homeowners need to be on top of them as their projects continue.
The images from London were so shocking that they are likely to fundamentally (and quite rightly) change our attitudes towards fire safety in homes, influencing the approach of designers, builders, building control inspectors, warranty providers and homeowners commissioning a project. This will influence building and renovating in the short term and long term.
Addressing Fire Safety in Your Design
So what can you do today? The best advice is to raise any concerns with your designer, your builder, and perhaps most importantly your Building Control inspector. Get it high on their agenda so that they can suggest ways to mitigate risk, choose products accordingly and so on.
It’s not really true to say that the current Building Regulations are insufficient to create safe, fire-resistant homes. Clearly, however, the Building Regulations provide a minimum standard (Grenfell Tower, as far as we know, met building control standards). It’s also worth bearing in mind that it’s almost impossible to entirely design out fire risk from new homes given the variety of the materials used in construction – but some materials are clearly better than others.
Insulation and Cladding
There is one immediate issue that the fire itself raised into sharp relief that apply specifically to renovators and some self builders: the use of external wall insulation and cladding. The main thing homeowners, designers and builders are trying to avoid is the element of what appears to be flammability or combustibility in the external walling system.
The system used on the Grenfell fire appears to have been a composite panel – an aluminium outer sheet with a polyethylene insulating core. Polyethylene (PE) is either high density (HDPE) or low density (LDPE) and most DIYers and builders would know it as the insulating sleeve commonly used around heating pipes. It is very rarely used as a mainstream insulation choice in the residential construction sector.
Specifying Materials with Fire Safety in Mind
The construction dispute specialists Probyn Miers issued an excellent paper on fire safety in relation to external cladding. It relates specifically to external composite panels, but the comments (pasted below) on specific materials will be of interest to those specificying insulation. It offers some reassurance to those currently specifying and building/renovating homes.
EPS (expanded polystyrene) will initially soften and shrink away from a small flame, but will then melt and burn. The voids created by melting admit oxygen, which intensifies the fire. Molten flaming droplets can spread the fire. All the material between the metal facings is likely to be consumed, leading to loss of structural stability. At the outset of the fire, development is fairly slow and contained. In a well-established fire, the material will contribute to the fire development. Delamination and collapse may be sudden. EPS was recognised as the worst of the plastic foams in fire conditions.
Extruded polystyrene (XPS) is a thermoplastic product equivalent to the flame retardant grade of EPS, but behaves similarly to EPS in fire conditions.
PUR is combustible. However, it forms a char layer which tends to inhibit further combustion. The char layer is relatively fragile. It may break off to expose fresh combustible foam. PUR also contributes to fire growth in a fully-developed fire, giving off black smoke and toxic fumes, including hydrogen cyanide above 850oC.
PIR, a variant of PUR having improved fire properties, is difficult to ignite and exhibits a pronounced charring which enables it to withstand fire for longer, but is ultimately combustible.
Phenolic foam (which manufacturers such as Kingspan use) is difficult to ignite. It chars, gives off fumes and burns with black smoke, but flame spread, smoke and toxic fume generation are moderate.
Rockwool mineral fibre, inorganic rock fibres bonded together with small amount of combustible binder, is non-combustible.
The full document, which is very useful and prescient in light of recent events, is well worth a read.
*Note. I’m going to add to this strand in the coming days as we discover more. I’d very much welcome comments too so we can build the knowledge bank for Homebuilding & Renovating members.