Facades & Fire Safety: Linear Route. Simple is not always best for over 18s

Facades linear route

Designing and installing a fire safe facade system, in principle, seems simple. Every component is already individually tested and graded for response to fire. By selecting materials which perform well in these tests, a high level of fire safety should be guaranteed. This is certainly the approach that the linear route to fire safety compliance takes, however, as we will explore, there are potentially significant draw backs from relying on these individual product ratings.

The linear route to compliance requires insulation to be of limited combustibility for English & Welsh properties, or non–combustible for Scottish ones. Importantly, if this route is taken it is not possible to mix and match materials so that combustible materials are used up to 18m whilst limited combustibility / non-combustible materials are installed at or above this height.

As virtually a tick box exercise, it’s understandable that some see this route as the easy, uncomplicated “catch all” solution. However, with façade systems, and building designs, becoming increasingly diverse and complex, the interactions between the various components can have a crucial impact on fire safety.

As the linear route does not consider the performance of the cladding system as a whole, it may not automatically deliver the best safety solution. It can also have a detrimental effect on other aspects of the build, such as thermal performance and overall wall thickness. As the real value of space blog series has shown, this can have a significant impact on returns on commercial buildings.

For more accurate results it is therefore advisable to use data from large scale testing of the entire facade system. When compared with small scale tests, this approach should provide much more reliable data on how a particular build-up will actually perform in the event of a fire.

If opting for this route, one thing to remember is that just because the insulation is of limited combustibility or non-combustible don’t think that you’ll automatically achieve compliance e.g. when combined with a combustible external cladding material.

Regardless of the insulation, there are separate requirements for the external wall surface i.e. for the façade itself, in relation to the building’s height, use and boundary. For instance, where the boundary of a building is no greater than one metre, the façade should be Class 0 / Low Risk / Euroclass B–s3d2 or better.

The next blog, which goes live on 15th December will explore the two performance based routes, which use large scale testing, in more detail, and show how it is still possible to take a look at the performance of the whole system even when large scale testing is limited or unavailable.

If you’d prefer to get into the detail of the full technical bulletin right away simply click here.

See the other posts in the Facades & Fire Safety Series:

Facades & Fire Safety: Which Way?
Facades & Fire Safety: Under 18? It’s all about classes and cavities
Facades & Fire Safety: Performance Route – Going Big on Testing

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Kingspan Insulation is a market leading manufacturer of optimum, premium and high performance rigid insulation products and insulated systems for building fabric and building services applications.

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