Cavity Wall Insulation

What is it?

Cavity wall insulation is used to reduce heat loss through a cavity wall by filling the air space with material that inhibits heat transfer. This immobilises the air within the cavity (air is still the actual insulator), preventing convection, and can substantially reduce space heating costs. Cavity Wall Insulation can save you up to 30% on your bills.

Saves you money and can increase the value of your house and significantly increases Home Energy Rating.

Prevents condensation (water repellent and fights against damp penetration), fewer draughts, keeps you warm, naturally fire resistant and works against vermin, inhibits mildew and fungi.

Has insulated more than 1 million dwellings and is independently guaranteed and environmentally friendly.

Rockwarm arrange for the insulation of your property to be carried out by their teams of fully trained specialists, approved by certification of both the BBA (British Board of Agreement) and by KNAUF Approved Installers. (NB – we do not sub-contract work)

Holes are drilled into the mortar line of the outer brickwork pattern, approximately 1.4 metres apart.

With semi-detached properties a cavity brush will be placed in the cavity flush to the adjacent property to prevent any spillage of material into the neighbours cavity. The loose wool is then blown into the cavity until it is tightly packed and no gaps are left.

A pressure sensor on the blowing machine cuts off the flow of material when it has reached the correct density in the cavity.

The holes are then re-filled with matching mortar, and the site is thoroughly cleaned after the installation is complete.

The material


Rockwarm has chosen KNAUF – SUPAFIL as its preferred supplier of insulation materials. As one of the market leading insulation product.


A tailor-made product designed to meet individual customer requirements, Supafil is a premium quality, non-combustible, glass mineral wool insulation designed to be blown into existing cavity walls. Supafil Cavity Wall Insulation is a loose, shot free, non-combustible glass mineral wool insulation which requires no mixing on site.

Your property will be regularly visited during the installation by one of our Quality Inspectors. Their role is to assess the quality of the installation at key stages and ensure that Rockwarm’s Health & Safety guidelines and procedures are being followed at all times.