What is Mineral Wool?

The mineral wool used for cavity wall insulation is made from mechanically granulated spun glass (or rock wool), which is then treated with a binder, and/or a water repellent, during manufacture.

This product is produced under strict quality control to ensure compliance with the British Board of Agrément (BBA) Certificate. Once installed, mineral wool is sufficiently stable to remain an effective insulant for the life of the building.

• Mineral wool has a very low thermal conductivity making it ideal for use as an insulator.
• It is non-combustible and therefore will not aid the spreading of a fire.
• It is resistant to water penetration and will not transmit water across the cavity or from below d.p.c. level by capillary action.
• It does not act as a water vapour barrier, therefore will aid the release of moisture through the wall.

Installation Procedure

• A pre-installation survey is carried out to assess the suitability of the property for the installation of cavity wall insulation.
• Where a semi-detached or terraced property is to be treated, the insulation is contained by inserting a cavity barrier at the dividing line dividing the properties.
• Injection holes of 22mm or 25mm diameter are drilled at a predetermined pattern/distance (depending on individual BBA certificate).
• Mineral wool is blown into the cavity via a flexible hose fitted with an injection nozzle, using an approved blowing machine.
• Filling proceeds from the bottom to the top of the wall and from one end of the elevation to the other.
• After injection of the insulant the holes are made good to match the existing finish as closely as possible.

Post Installation Checks

All necessary air vents are checked e.g. those providing under-floor ventilation and combustion air. In all cases flues are carefully checked on completion of the installation by means of an appropriate test to ensure they are not obstructed by the insulant.

Further information and useful links

• Find a Insulation Installer near you
• Find a Builder near you

• National Insulation Association
• Energy Savings Trust (est.org.uk)
• Cavity Insulation Guarantee Agency (ciga.co.uk)
• Building Regulations an explanatory booklet (odpm.gov.uk)
• Party Wall Guidance (rics.org)
• Impact of the Party Wall Act 1996 (communities.gov.uk)