Do I need FENSA or CERTASS registration to install windows?

No — registration isn’t a legal requirement to fit windows, but compliance with the Building Regulations is. Replacement windows are controlled fittings, and any installer fitting them must demonstrate compliance, the simplest route being a FENSA or CERTASS registered installer who self-certifies the work under the Competent Person Scheme and provides a certificate.

If you’re registered with FENSA or CERTASS (both are government-authorised schemes carrying equal legal weight), you self-certify your own work and the scheme notifies building control on your behalf. If you’re not registered — for example a general builder or a fitter working occasionally — you can still legally install windows, but the work must be signed off another way: by submitting a building notice to the local authority’s building control before starting, so they can inspect and issue a completion certificate. The legal requirement is not about who does the installation; it is about whether the installation complies with Building Regulations. 

In short: registration saves you the paperwork and the building control fee, and it’s what most homeowners now expect when selling. But the windows themselves must meet the standards either way — and every product we supply is manufactured to meet current Part L thermal requirements, with written specifications available for any building control inspector if required. It’s an easier process to find an installer who is CERTASS or FENSA registered in the first place.