The typical cavity wall insulation guarantee lasts 25 years from the date of installation, provided the work is carried out by a certified installer under the CIGA scheme, according to the Cavity Insulation Guarantee Agency (GOV.UK, 2026).
The guarantee length applies to installations completed by companies registered with CIGA, which covers most professional cavity wall insulation jobs in the UK. If the installer is not CIGA-registered, the guarantee may be shorter or non-existent. The 25-year guarantee is transferable to new homeowners, adding value when selling a property. However, it only covers defects in materials or workmanship, not damage from external factors like structural movement or flood damage.
CIGA guarantee covers installation defects only
The CIGA guarantee protects against issues such as poor filling, gaps in the insulation, or moisture ingress caused by incorrect installation. It does not cover general wear and tear, damage from damp that existed before installation, or problems arising from alterations to the property. Energy Saving Trust advises checking the guarantee terms carefully, as some claims require proof that the property was suitable for cavity wall insulation at the time of installation (Energy Saving Trust, 2026). If a defect appears within the 25-year period, the installer or CIGA must rectify it at no cost to the homeowner.
Guarantee is non-transferable if not registered
If the original installer was not registered with CIGA, the guarantee is not automatically transferable to a new owner. For CIGA-registered installations, the guarantee stays with the property, not the homeowner, and can be passed on when you sell. TrustMark recommends checking the CIGA registration number on the guarantee certificate before purchasing a home with cavity wall insulation (TrustMark, 2026). Without a CIGA certificate, you may have no recourse if issues arise later.
Guarantee does not cover performance over time
The guarantee does not guarantee the insulation will maintain its original thermal performance for 25 years. Over time, cavity wall insulation can settle, become damp, or be damaged by rodents, reducing its effectiveness. The government’s Standard Assessment Procedure (SAP) assumes a lifespan of around 40 years for cavity wall insulation, but this is an estimate, not a guarantee (BRE, 2026). If you notice higher energy bills or cold spots, a professional survey can assess whether the insulation is still performing adequately, but the CIGA guarantee will not cover performance degradation unless it results from a defect.
Frequently Asked Questions
The typical cavity wall insulation guarantee lasts 25 years from installation, according to the Cavity Insulation Guarantee Agency (CIGA) and GOV.UK (2026). This applies only if the work is done by a CIGA-registered installer.
Yes, the 25-year CIGA guarantee is transferable to new homeowners, which can add value when selling the property. The Energy Saving Trust recommends confirming the transfer in writing.
The guarantee covers defects in materials or workmanship, such as poor filling or moisture ingress from incorrect installation, according to CIGA. It does not cover external damage like structural movement or pre-existing damp.
