UPDATE ON USING COMBUSTIBLE MATERIALS ON BALCONIES

At the end of June 2019, the UK Government issued an advice note regarding balconies on residential buildings and fire safety. The advice note followed the amendments made to the Building Regulations at the end of 2018, which we wrote about in this blog post.

A fire at a block of flats in Barking at the beginning of June is widely seen as being the driver for the issuing of new advice. The balconies on the development were clad in timber.

The latest advice note from the Ministry of Housing, Communities and Local Government (MHCLG) is available here.

What does the new advice note say about balconies?

Paragraph 1.4 of the advice note says:

“The view of the Expert Panel is that the removal and replacement of any combustible material used in balcony construction is the clearest way to prevent external fire spread from balconies and therefore to meet the intention of building regulation requirements…”

There is no reference to balconies as ‘specified attachments’ (a term used in the Building Regulation revisions at the end of 2018), or how a flat roof that forms part of the thermal envelope and acts as a balcony should be considered.

Using XPS insulation in inverted warm roofs acting as balconies

As with any sensitive topic like fire safety, consultation with the appropriate authorities and professionals should always take place when considering any design and specification. On this issue, that could be a fire engineer, the local fire service, or the Building Control Body carrying out inspection and approval work.

Paragraph 2.1 of the new advice note says:

“Balcony fires can spread to the adjacent balconies or into the building. If combustible materials have been used in the balcony or external wall system, it is possible that fire may spread rapidly across the façade. The risk is increased if combustible materials are used extensively (i.e. in floors and facades of balconies and in certain geometries).”

It does not mention flat roofs, but the use of the word “extensively” in connection to floors may lead people to interpret that a thermal insulation layer comprising combustible material is not acceptable.

However, we would still maintain that this only applies in the case of a balcony being outside the thermal envelope of the building. The ‘floor’ of a balcony could comprise timber boarding or another combustible finish. As we wrote in February 2019:

“If the balcony is insulated then that means it is over a heated space. It therefore becomes a thermal element in its own right – i.e. a flat roof – and is subject to all other necessary Building Regulations requirements – including fire safety.”

Paragraph 2.4 of the new advice note would appear to support this view, as it says:

“Building owners need to ensure that any balconies do not compromise resident safety by providing a means of external fire spread.”

Preventing external fire spread in flat roofs

An inverted warm flat roof, featuring extruded polystyrene or any other type of combustible insulation, would achieve this aim. It is not part of the external wall construction, and the specified build up would achieve the external fire spread requirements for a flat roof.

However, the advice note does not provide this level of clarification, and the possibility remains for confusion over flat roof constructions that accord with the regulations, but which have been designated as balconies as part of the scheme design.

We will continue to work with our industry colleagues to try and achieve the level of clarity needed to avoid this confusion. In the meantime, should you or your Building Control Body have any questions or concerns about the use of Polyfoam XPS products on projects where this sensitive area of regulation applies, contact us to discuss the design and specification.

Published June 2019.

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