Most types of insulation should last for at least 20 years, and in many cases they will last for much longer than this. Many varieties of loft insulation, for example, should last for at least 40 years.
For cavity wall insulation, installations completed by registered professional installers are guaranteed by the Cavity Insulation Guarantee Agency (CIGA) for 25 years. A list of registered installers is available on the CIGA website:
For domestic injected polyurethane cavity wall insulation projects British Urethane Foam Contractors Association installer members can offer a 25 year insurance warranty. 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, by prior approval of the insurers. 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. www.bufca.co.uk
Professionally installed external wall insulation should come with a warranty of at least 10 years, though this will vary depending on the supplier/installer and manufacturer.