FENSA and Competent Person Schemes: What Certification Covers When You Replace Conservatory Glazing
Replacing windows or doors on an existing conservatory usually falls under Building Regulations — and a Competent Person Scheme like FENSA is the mechanism most installers use to self-certify that work.
In this guide
If your conservatory’s windows or doors are being replaced, that work is normally subject to Building Regulations — and the certificate you’re given afterwards is the paper trail proving it was done, and signed off, correctly.
Why replacement glazing is controlled at all
Replacing windows, doors or roof glazing is not simply a like-for-like swap in the eyes of Building Regulations — the replacement needs to meet current thermal performance and safety glazing standards, even where the original installation predates those standards. This applies to conservatory glazing just as much as to the main house, which is why a seemingly simple job like replacing a failed double-glazed unit can still trigger a formal compliance requirement.
What a Competent Person Scheme actually does
Gov.uk’s guidance on Competent Person Schemes explains that members of these schemes can self-certify certain types of building work, meaning you do not have to get a local council or private approved building inspector to separately check the work. This matters practically: without self-certification, you would otherwise need to arrange and pay for a building control inspection yourself to get the same compliance confirmation. Different schemes cover different trades, so it’s worth choosing an installer registered with a scheme that actually supports the type of work being carried out on your conservatory.
FENSA specifically, and how it fits in
FENSA (the Fenestration Self-Assessment Scheme) is the best-known Competent Person Scheme covering window and door installers in England and Wales, and is the scheme most homeowners will encounter when replacing conservatory glazing specifically. An installer registered with FENSA (or an equivalent scheme) can certify their own work as compliant with Building Regulations, notify the local authority on your behalf, and issue you a certificate confirming this — without a separate building control visit being required.
What you should receive once the work is finished
After a compliant installation, you should be issued a certificate confirming the work has been notified and certified under the relevant Competent Person Scheme. This document matters beyond the moment of installation:
- It’s evidence for a future buyer’s solicitor that replacement glazing was carried out lawfully, avoiding delays or retrospective certification costs when you come to sell.
- It may be requested by your home insurer in the event of a claim connected to the glazing.
- It confirms the specific safety and thermal standards the installation was actually tested against.
Keep this certificate with your other property paperwork, in the same place as any planning permission or building regulations records for the conservatory itself — missing documentation is a genuinely common snag in property sales involving a conservatory (see our separate guide on buying a house with a conservatory).
If your installer isn’t registered with a scheme
Using an installer who isn’t part of a relevant Competent Person Scheme doesn’t automatically mean the work is unlawful, but it does mean the self-certification route isn’t available to them — and Building Regulations compliance still needs to be demonstrated some other way, typically by applying to building control directly and paying for an inspection. This is worth factoring into any quote comparison: a lower quote from a non-registered installer may not include the cost, or the hassle, of arranging that separate building control sign-off yourself.
FAQs
Does every conservatory glazing job need a FENSA certificate?
Most replacement glazing work is notifiable under Building Regulations, but the specific requirements can depend on the exact scope of work. If in doubt, ask your installer directly which scheme they’re registered under and confirm before work starts, rather than after.
Is FENSA the only Competent Person Scheme covering windows and doors?
No, other schemes also cover this type of work. What matters is that your installer is registered with a scheme that actually covers the specific trade and work being carried out, not necessarily FENSA by name.
What if I’ve lost my certificate from a past installation?
It’s usually possible to request a duplicate or confirmation from the relevant scheme, since records are typically held centrally rather than only by the original installer, who may no longer be trading.
Sources
This guide draws on the following primary sources, current as of 16 September 2026:
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Compare Conservatories is an independent guide. We may earn a fee from some links; this never affects what we write. This article is general information, not legal advice on any specific property — always confirm with your Local Planning Authority.