Customers often call us to ask whether external wall insulation is safe to install on their homes. EWI Pro systems are BBA approved, which means that they have been rigorously tested by the British Board of Agrément, who have deemed that they are safe and suitable for installation onto UK homes.
Cladding materials have had a lot of negative press recently, being the source of heated debates over how trustworthy certain materials are. While external wall insulation can be classed as a type of cladding, it’s worth noting that it is completely different to rainscreen cladding – the material that resulted in the Grenfell fire tragedy.
In today’s blog post we’re going to be discussing how our external wall insulation systems have been designed to ensure the highest level of safety.
Securing External Insulation Boards – Dual Fixing
The EWI Pro system is designed so that the external wall insulation boards are fixed to the substrate using the dual-fixing method of both adhesive and mechanical fixings. This ‘belt and braces’ design ensures the stability of the system so that in the unlikely event that the adhesive fails, the fixings are still there to hold the boards up.
The EWI Pro system also consists of two adhesives of different strengths. For example, our Premium Basecoat (EWI-225) is our strongest adhesive and so is always used with Mineral Wool insulation boards which are much heavier. Alternatively, the EPS Basecoat (EWI-220) is ideal for use with lightweight foam insulation boards such as EPS and XPS. Ensuring that the adhesive is of the correct strength for the weight of the insulation board is essential for a safe and secure system.
Fire Safety of External Wall Insulation Materials
How fire safe your system is will greatly depend upon the type of insulation that you choose.
Rockwool Mineral Wool boards are rated as Euroclass A1 non-combustible and are therefore the safest insulation material that you can have installed on your property. The Rockwool insulation boards work to contain the fire and prevent it from spreading throughout the building. As well as this, they don’t release toxic emissions or smoke when exposed to fire.
The EPS system has been designed in such a way so that in the event of a fire the EPS would simply melt within its cement-based plaster enclosure. The mechanical fixings would support and hold the structure in place, so although the system wouldn’t withstand the fire, it wouldn’t contribute towards the spread of it.
Wood Fibre, on the other hand, is known to char rather than burn. You’d think that being wood it would go up in flames very easily, however, timber burns very slowly and this charring effect actually creates an oxygen barrier which helps to slow down the spread of the flames.
Fibreglass Mesh for Reinforcement
We often talk about the use of reinforcement mesh in the context of ensuring that the render topcoat doesn’t crack. However, Fibreglass Mesh plays an important role within the external wall insulation system, enhancing its tensile strength to keep the boards securely tied to the wall.
Fibreglass Mesh strips are embedded within the basecoat layer and are overlapped by 10cm across each edge. This creates an added layer of reinforcement that spans across the entire surface area of the system.