Question to the Department for Energy Security & Net Zero:

To ask the Secretary of State for Energy Security and Net Zero, what steps he is taking to inform the public about the level of risk of (a) moisture and (b) timber degradation following the application of sprayed foam insulant to typical domestic timber roofs.

The Building Safety Regulator published research in March 2024 on the moisture risks from spray foam insulation, which showed that there are many situations where moisture risks are likely to be low, including when insulations are made in line with BS 5250:2021. This research did indicate there is a potential for risks to develop dependent on the specifics of roof assembly, temperature, and humidity conditions.

The research can be found here: https://www.gov.uk/government/publications/moisture-risk-of-spray-foam-insulation-applied-to-timber-sloped-roofs.

All measures installed under government schemes must be installed by TrustMark registered installers and meet the industry standard for installation. If a product has been installed to the standard it should not require removal as a surveyor should be able to use the inspection protocol now available to make an assessment.

Where the measure has not been installed correctly, homeowners should contact their installer or use the TrustMark dispute resolution process to seek redress (https://www.trustmark.org.uk/homeowner/information-guidance/if-things-go-wrong).