We are delighted to be able to offer Rockwool insulation as part of our external wall insulation systems. Rockwool are currently the world leaders in the manufacture of mineral wool insulation, manufacturing their stone wool from a blend of naturally-occurring volcanic diabase rock. This rock is heated to an incredibly high temperature and spun (much like candy floss) into a fine wool that then can be used as an insulation material for many different purposes.

Rockwool historically have made rolls of loft insulation and cavity batons; however the insulation we sell is specifically made for solid wall insulation.

The stone wool is compressed into dual density rigid boards. The outer most surface of the insulation board is compressed to a higher degree than the rest of the board. This means the surface is that bit stronger and therefore it provides more compressive strength when used in the insulation system.

The Advantages of Rockwool

Rockwool has some significant advantages over other insulation materials which are discussed briefly below:

  • Rockwool stone wool fibres can withstand more than 1000°C without melting – this means it can slow the spread of fire in a property where it to catch fire.
  • Rockwool has fantastic thermal insulating properties. 120mm of our dual density slabs when attached to the exterior of a property will take the u-value down to 0.3 which means the building will then conform to building regulations. For the occupants, it means improved thermal comfort since the property will stay at more even temperatures and also lower energy bills.
  • Rockwool stone wool has great acoustic insulating properties, so it can really can help with sound reduction if installed on a busy road for example.
  • The final advantage is that Rockwool is breathable, therefore it allows moisture to travel across the wall which can help dissipate damp (from in the house).

In order to use Rockwool stone wool in our external wall insulation systems, you do need to use slightly different materials, because the adhesive required to stick the boards on to the wall needs to be slightly stronger. Since the Rockwool is also breathable, we don’t sell acrylic render for use on this system as it slightly defeats the object!

Looking for a Quote for Rockwool? Try our calculator tool!

How to Install a Rockwool EWI System

When installing Rockwool as part of a Mineral Wool external wall insulation system, we recommend the use of our Premium Adhesive. This is our strongest and most breathable adhesive; it contains strands of fibreglass within the material, which enhances its tensile strength and adhesive capabilities. The Premium Adhesive is used to secure the Mineral Wool boards to the substrate, before metal mechanical fixings are drilled in to provide an extra secure fit. Metal fixings must be used in conjunction with Rockwool because this is a much heavier insulation material and plastic fixings wouldn’t be able to take the weight of the boards.

From then on, the Premium Adhesive can be used on top of the boards as a basecoat, with strips of overlapping fibreglass mesh embedded within it, before it is finished with either our Silicone or Silicone Silicate renders. We advise using these renders as they are our most breathable and therefore will work well in conjunction with the Rockwool which is, as stated above, a highly breathable insulation material.

Looking for a comparison between all three of our insulation materials? Have a read of our blog post ‘the best insulation material for EWI?’. We’ve also previously written all about our Wood Fibre insulation and the advantages of that on another blog post, so have a read before making a decision!

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