Polyurethane foam for cavity wall insulation

Member Article

Polyurethane foam: a multi-purpose solution for cavities

When it comes to cavity wall insulation there is only one product that provides an all round solution and that is injected polyurethane foam insulation. Not only does it provide superior thermal insulation but it also helps bond the inner and outer leaves together to provide additional stability to the building fabric. In fact, there are many advantages to installing polyurethane foam.


Polyurethane foam is a two-component liquid system which produces a highly-efficient blanket of insulation. The cured foam offers outstanding performance by combining low thermal conductivity characteristics (approximately twice as efficient as fibreglass) with an air barrier that eliminates heat loss through air leakage. By outperforming all other forms of cavity fill it is particularly cost-effective and is easily applied to a wide variety of substrates.

Structural stability:

The polyurethane foam insulant helps to bond the inner and outer cavity leaves together, providing structural stability to the building. This is particularly important where wall-ties have failed, or are starting to deteriorate as this can help avoid costly remedial or replacement work prior to any treatment being carried out. The processed raw material is injected as a fluid or ‘syrup’ which flows throughout the whole cavity, avoiding the clumping or blockages sometimes associated with conventional materials or poor quality installation. This ensures that the cavity is fully filled reducing the risk of condensation, mould growth and other problems associated with cold spots arising from missing insulation.

Moisture impermeable:

In severe or coastal exposure zones more conventional cavity insulation materials may not be an option as the exposure ratings may make them unsuitable. However, the moisture impermeable, non-slumping properties of polyurethane foam enables it to be installed in all exposure zones. In the UK there are 5.2 million homes in flood risk areas. Flood waters penetrating properties can cause serious damage to the building substrate, the cavity wall ties and internal finishes. Where housing is susceptible to flooding, the installation of polyurethane foam to the cavity helps to stem the flow of water through the walls. The material’s closed-cell nature renders it very resistant to moisture ingress and it can often be used when other forms of cavity fill are not suitable.

Hard to treat Construction:

Injected polyurethane foam cavity insulant can be used to insulate hard-to-treat housing. This could include properties with narrow cavities, stone cavities, failing wall ties, or a metal frame or timber framed construction, where other cavity insulation materials are often precluded.

The English Housing Survey published in 2014 sited 4.9 million homes both in private and public sector ownership as not meeting the Decent Homes Standard in 2012. Many of these can be brought up to current standards of thermal insulation simply by installing polyurethane foam.

BUFCA Warranty:

The British Urethane Foam Contractors Association is the national trade association representing the spray applied and injected polyurethane foam industry. BUFCA has a network of contractors skilled in the installation of sprayed or injected polyurethane foam.

When choosing a member, specifiers can be assured of the highest standards of quality and service. Installers are required to abide by the Association’s Code of Professional Practice which aims to further good technical and professional conduct and promotes sound relationships between members and their customers. A survey is carried out before installation to check that the building fabric is sound, with any necessary rectification works carried out.

There is a twenty-five year insurance warranty which BUFCA installer members can offer for domestic injected polyurethane cavity wall insulation projects. The warranty offers reassurance to customers and becomes effective if there is a fault with the installation or the product and the installer or product manufacturer has ceased to trade.

The BUFCA warranty is available for installations funded as part of Energy Company Obligation or Green Deal Home Improvement Funded work. Other domestic and commercial jobs can also be considered, subject to prior approval by the insurers.

Technical datasheets and literature on the use of injected polyurethane for walls is available from the BUFCA website at www.bufca.co.uk.

This was posted in Bdaily's Members' News section by BUFCA .

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