Mineral Wool insulation is a great choice for an external wall insulation install; it’s rated as A1 noncombustible, it’s breathable and it has excellent thermal performance.

However, when it comes to EWI it’s essential to get the fixings right to ensure a high level structural stability. Especially with Rockwool (Mineral Wool) insulation, which is a much heavier material than, for example, EPS which is a lightweight expanded polystyrene.  

Mineral Wool is a premium insulation material, but along with the benefits it offers it requires a level of responsibility when installing it.

Metal Fixings for Mineral Wool

Because Mineral Wool is that much heavier, it’s necessary to use metal fixings to secure it to the substrate. The fixing also needs to be thread through a support disc to help spread the load across a greater area.

Reinforcements are essential for installing Mineral Wool insulation. Below you can see a picture of how the fixing should look when installed properly.

As you can see, the fixing is made up of three components. The metal pin, the plastic body and the fixing disc.

The central portion of the plastic ring is the plastic body of the fixing – this is where the metal pin is threaded through. The outer ring of plastic around this is the reinforcement disc:

fixings mineral wool

 

In the following picture, you can see the plastic body of the fixing installed without the metal pin or the reinforcement disc:

wrong fixing mineral wool

 

Fixings come with an exterior plastic body to prevent thermal bridging. Plastic is a poor thermal conductor, and so when installed in an insulation system it works to prevent heat escaping from the walls directly through the fixings.

Thermal bridging is highly detrimental to an insulation system, so every action needs to be taken to ensure that it is reduced to a minimum; using fixings with plastic bodies ensures that the system remains as a effective as possible.

Adhesive for Mineral Wool

At EWI Store, we always advise installers that for Mineral Wool insulation it’s imperative that they use the Premium Basecoat adhesive (rather than our EPS adhesive) for securing the boards to the substrate. This is because the Premium Basecoat contains portland cement which has much higher adhesive capabilities.

 

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