FENSA, CERTASS and Assure certificates explained

Almost everyone calls it "a FENSA certificate". What people actually mean is a Building Regulations compliance certificate for replacement windows or doors — and FENSA is only one of the three schemes that can issue one.

Why the certificate exists

Since April 2002, replacement windows and external doors in England and Wales have been notifiable work under the Building Regulations. The work has to be certified as compliant, and there are two ways to get there.

The two routes

A Competent Person Scheme. A registered installer self-certifies their own work and the scheme issues the certificate, usually within a few weeks. No local authority involvement and no separate fee.

Local authority building control. You notify the council yourself, pay their fee, and they inspect and issue a completion certificate. This is the route on a supply-only order, because no registered installer was involved.

The three schemes are equivalent

There are three Competent Person Scheme providers for replacement glazing: FENSA, CERTASS and Assure. All three are UKAS-accredited and government-authorised, all three certify against the same Building Regulations, and a certificate from any of them satisfies a solicitor. FENSA is simply the oldest and best known, which is why its name became the generic term.

Assure is authorised by the Ministry of Housing, Communities and Local Government for the replacement of windows, roof windows, rooflights and doors in England and Wales. You can verify any installer's registration using the company search on the relevant scheme's own website — and you should, rather than taking a logo on a van at face value.

Where we sit

We are registered with Assure. If we install your windows or doors, we self-certify the work and your compliance certificate follows automatically — you do not contact building control and you do not pay a council fee.

If you buy supply only, no scheme covers it, because certification attaches to the installation rather than to the product. You notify building control yourself. What that involves.

Scotland and Northern Ireland

Competent Person Schemes are an England and Wales mechanism. Scotland operates its own building standards system with completion certificates through the local authority, and Northern Ireland has its own building control arrangements. If you are outside England and Wales, take the certification route from your own local authority.

Why it matters when you sell

A buyer's solicitor will ask for the certificate for any window or external door replaced since April 2002. Not having one means an indemnity policy, a price retention, or a delay — at exactly the worst moment. If you have lost yours, the scheme can usually reissue it. If the work was never registered, regularisation through the council after the fact is possible but more expensive and more irritating than doing it at the time.