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Cavity Wall Insulation

Information regarding the injection of cavity wall insulation including routes to compliance and current competent person schemes.


Cavity Wall Insulation Injection

The Government regards cavity wall insulation as one of the most effective energy savings measures that most people can carry out on their homes and apart from saving money it is a major contributor to reducing emissions of carbon dioxide through the conservation of fuel and power.

The injection of cavity wall insulation is a relatively simple process by which insulation is injected into this cavity through a series of holes. The injected insulation will have been designed so that any water that does enter the cavity can drain away, whilst the insulation still reduces the heat loss through the wall.

External walls can account for around 35 percent of heat loss from the average house, studies suggest that every square metre of cavity wall insulation will save more than a tonne of carbon dioxide over the average life of the building. For a semi detached house
with an external wall area of 80 square metres, this roughly equates to savings of 80 tonnes.

Insulation types

There are a number of different products each of which must pass strict technical requirements laid down by the British Board of Agreement (BBA) or an alternative independent approvals body.

Currently there are three main systems in common use, all of these are suitable for the purpose of cavity injection and with the exception of Urea Formaldehyde Foam (UF Foam) can be used in all areas of the UK. These are manufactured by a number of companies for which more information can be found on the web site of the Cavity Wall Guarantee Agency (CIGA) [external link]. These insulations are as follows:-

  • Mineral wool insulation is a cotton wool like material produced from either rock wool or glass wool, and is used in the majority of installations,
  • Polystyrene bead is made up of small expanded polystyrene beads normally injected with a binding agent, and
  • Urea Formaldehyde foam cavity wall insulation was introduced into the UK in the late 1960's and involves the injection of a water based chemicals system that once injected produces an insulating foam in the cavity.

The installation of cavity wall insulation is covered by requirements of the Building Regulations, however as long as you use an installer who is registered with the Cavity Insulation Guarantee Agency Limited [external] competent person scheme, you will not need to apply for permission from Building Control as the installer will notify their competent person scheme provider, who will in turn notify us.

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