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FENSA certificates and building regs explained

Replacement windows are covered by building regulations, and the paperwork proving they comply matters — especially when you come to sell. Here is what a FENSA certificate is, why you need one, and what to check when your installer hands over the documents.

Why replacement windows are regulated

Since 2002, replacing windows and doors in England and Wales has been notifiable work under the building regulations. New windows must meet minimum standards for thermal performance, ventilation, safety glazing and, in some rooms, means of escape. The rules exist to keep homes warm, safe and properly ventilated. Meeting them is one reason a modern unit deals so well with the everyday problems new windows solve, from draughts to condensation.

What is a FENSA certificate?

FENSA is a government-authorised scheme that lets registered installers self-certify that their work meets the building regulations, without you having to involve your local authority's building control separately. When your windows are fitted by a FENSA-registered company, they register the job and a certificate is issued confirming compliance. Certass is a similar competent-person scheme; either is acceptable. If your installer is not part of a scheme, the work has to be signed off by building control instead, which usually means a fee and an inspection.

What paperwork you should receive

After a compliant installation you should end up with:

• A FENSA (or Certass) certificate confirming the work meets building regulations. This usually arrives by post or email within a few weeks of the fit.
• Your insurance-backed guarantee, which protects the workmanship even if the company were to cease trading.
• The manufacturer's product guarantee for the frames and sealed glass units.
• Energy-rating information for the glazing, so you can see how it performs.

Keep these somewhere safe. On installation day your fitter should tell you when the certificate will follow — see our installation day guide for how the handover works.

Why it matters when you sell

When you sell your home, the buyer's conveyancer will ask for FENSA certificates covering any windows replaced since 2002. Missing paperwork can slow a sale or force you to buy indemnity insurance. Getting the certificate at the time, and filing it with your house documents, saves that headache years down the line. It is one more reason to take care vetting your installer first and to make sure certification is part of the price — a point worth confirming during your window survey.

What if the certificate does not arrive?

If a few weeks pass and nothing turns up, chase your installer first — they hold the registration. You can also confirm a certificate exists through the FENSA website using your address. If you hit a wall, our aftercare and snagging guide explains how to escalate an unresolved issue. Planning several improvements at once? A broader home improvement quote comparison can help you keep all the compliance paperwork in one place.

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