How do rainscreen cladding systems prevent fire spread?

Rainscreen cladding has many benefits; it protects the building’s exterior from the elements, improves a building’s thermal performance, adds visual interest and (most importantly) prevents fire spread.

In a nutshell:

  • Rainscreen cladding protects the exterior of buildings from the elements
  • The system works through ventilation which prevents moisture build-up
  • Amendments to the Building Regulations in 2018 banned the use combustible materials on high-rise buildings
  • Non-combustible materials include: terracotta, ceramics, aluminium and mineral wool insulation
  • Compartmentalised cavity barriers prevent the spread of fire for up to 120 minutes depending on the system build up

How do rainscreen cladding systems prevent fire spreadRainscreen cladding works using a ventilation system; the gaps in between the system promotes the circulation of air behind the façade which dries and removes moisture build-up. By expelling moisture, the system also reduces the risk of damp and rot.

This ventilation is facilitated by an open cavity; although the cavity also presents a potential risk as it creates a chimney for fire to spread on the outside of the building. This can be tackled with vented intumescent fire barriers, which activate a strip that closes off the horizontal cavity at a certain temperature and offers up to 120 minutes of integrity.

Following recent changes to legislation, the government made amendments to the Building Regulations stating that ‘any insulation product, filler material (not including gaskets, sealants and similar) etc. used in the external wall construction should be of limited combustibility.’

In light of this, terracotta and aluminium are most commonly specified as cladding panels.

Another way in which rainscreen cladding systems can prevent fire spread is through the insulation layer. When it is made from non-combustible materials such as rock mineral wool, glass mineral wool or blowing wool, the layer helps to minimise the outbreak of fire.

It is important to always consult fire safety experts when specifying cladding products.

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