Before they ask:
Lost your FENSA certificate for replacement windows?
Replacement windows fitted in England and Wales from April 2002 normally need building regulations compliance, usually evidenced by a FENSA or CERTASS certificate. You can look yours up online in minutes, and a replacement copy is around £25.
- How long
- Minutes to look up
- Typical cost
- Around £25 for a copy
- Who asks
- Buyer's solicitor
This is one of the few enquiries on the list you can genuinely close in an afternoon, which is a good reason to do it before anyone asks.
The rule
From 1 April 2002 in England and Wales, replacement windows and glazed external doors came within the building regulations. Compliance is normally evidenced in one of two ways:
- A self-certification scheme certificate — FENSA and CERTASS are the two you will encounter most often — issued because the installer was registered and self-certified the work.
- A building control completion certificate, where the work was notified to the council instead.
How to find yours
Both FENSA and CERTASS operate online lookups. You search by address and, if the work was registered, you can order a duplicate certificate. It typically costs around £25 and arrives quickly.
This is worth doing before you list, for a reason that has nothing to do with the certificate itself: it tells you the date the windows were registered, which answers a question you will otherwise be guessing at on the property information form.
If nothing comes up
Three possibilities, in order of likelihood:
- The windows predate April 2002. No certificate exists and none is expected. Say so.
- The installer was not scheme-registered and notified building control directly. Your council building control record would have it — but read the note below first.
- The work was never notified. This is the one that needs your conveyancer.
Before you ring the council. If the windows may have gone in without any notification, do not approach building control about it before speaking to your conveyancer. Indemnity insurance is a common route for unnotified work, and insurers generally require that nobody has raised it with the local authority. See the indemnity trap.
What the energy certificate can tell you
Your EPC records the glazing type, and on more recent certificates it distinguishes between glazing installed before 2002 and during or after 2002. That is not proof of compliance, but it is a useful pointer to whether a certificate should exist at all — and it is free to look at.
Older certificates do not record the install date, in which case the EPC cannot settle the question either way.
Common questions
What if the windows went in before 2002?
Then the self-certification schemes did not exist yet and no certificate will be found, which is a perfectly normal answer. Say when they were fitted, as best you know. This is one of the easier enquiries to close once you can date the work.
What if the installer was not registered?
Work by a non-registered installer should have been notified to building control directly, which would produce a completion certificate instead. If neither exists, this becomes the same conversation as any other missing building regulations sign-off — and the same warning applies about contacting the council before speaking to your conveyancer.
Does this cover doors too?
External doors with significant glazing are generally within scope on the same basis as windows. If a door was replaced at the same time as the windows it is usually on the same certificate.
Is a FENSA certificate a guarantee?
No, and this trips people up. It evidences building regulations compliance. Any workmanship guarantee or insurance-backed guarantee is a separate document from the installer, and buyers sometimes ask for that as well.
Last reviewed 13 September 2026. England and Wales.
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