If you are having new windows or doors fitted, you will hear about FENSA certificates. This document is the official proof that your installation meets UK Building Regulations, and it has a direct impact on your legal liability and your ability to sell your home.
A FENSA certificate is the official proof that your replacement windows or doors meet UK Building Regulations. Without it, you could face fines from your local council and problems when selling your home.
What matters when you choose a FENSA certificate is that it is not optional, it is a legal requirement for replacement windows and doors in England and Wales under Building Regulations. When you hire a FENSA-registered installer, they self-certify the work and lodge the certificate with FENSA, which is then recorded on the central database. This protects you when selling: buyers’ solicitors will ask for it, and without it you may need retrospective building control approval or indemnity insurance.
| Certificate Type | Issuing Body | Purpose | Typical Cost |
|---|---|---|---|
| FENSA | FENSA | Self-certification for replacement windows/doors | Included in installer’s fee |
| Competent Person Scheme (other) | CERTASS, BBA, etc. | Alternative self-certification | Included in installer’s fee |
| Building Regulations Completion Certificate | Local Authority | Full building control approval | £200–£400 |
1. FENSA certificates prove Building Regulations compliance
A FENSA certificate is your proof that the installation meets the required standards. FENSA-registered installers self-certify that windows meet thermal and safety standards set out in the Building Regulations (FENSA, 2026). Without this certificate, your local council can demand that non-compliant installations be removed or corrected (GOV.UK, 2026). This is a legal requirement, not a recommendation.
- FENSA-registered installers self-certify compliance with thermal and safety standards
- Local councils can demand removal of non-compliant installations without a certificate
2. You must get a certificate for replacement windows
All replacement glazing in England and Wales requires Building Regulations approval (GOV.UK, 2026). FENSA covers most domestic replacement work, but not new-build properties or listed buildings, which require separate listed building consent (FENSA, 2026). This means that if you are replacing existing windows in a standard home, the installer must be registered with a Competent Person Scheme like FENSA.
- All replacement glazing in England and Wales requires Building Regulations approval
- FENSA covers most domestic replacement work, not new-build or listed buildings
3. Selling your home requires a FENSA certificate
When you sell your home, the buyer’s solicitor will ask for the FENSA certificate as part of the conveyancing process (Energy Saving Trust, 2026). Without it, you may need to buy indemnity insurance or apply for a retrospective building control application, which can delay the sale and cost you money (GOV.UK, 2026). guide to selling a home with non-compliant windows
- Buyers’ solicitors request the certificate during conveyancing
- Without it, you may need indemnity insurance or a retrospective building control application
4. FENSA installers handle the certification for you
If you hire a FENSA-registered installer, they handle the entire certification process. After the installation is complete, the installer registers the work with FENSA (FENSA, 2026). You should receive your certificate by post or email within a few weeks. This is included in the installer’s fee, so there is no separate charge for the certificate itself.
- The installer registers the work with FENSA after completion
- You receive a certificate by post or email within a few weeks
5. Missing certificates can be found on the FENSA database
If you have lost your FENSA certificate, or if you bought a property where the previous owner did not pass it on, you can check the FENSA database. FENSA holds a searchable online record of all registered installations (FENSA, 2026). You can search using your postcode and the installation date to find a copy of the certificate.
- FENSA holds a searchable online record of all registered installations
- You can check using your postcode and installation date
6. Retrospective certificates are possible but costly
If you have no FENSA certificate and the work was not registered, you can apply for a Regularisation Certificate from your local authority (GOV.UK, 2026). This involves an inspection of the windows to check they meet standards, and it can cost between £200 and £400 (GOV.UK, 2026). This is more expensive and time-consuming than having the certificate from the start.
- You can apply for a Regularisation Certificate from your local authority
- This involves an inspection and can cost £200–£400
7. FENSA covers energy efficiency standards
Part L of the Building Regulations sets minimum energy efficiency standards for replacement windows. Windows must meet minimum U-values, typically 1.4 W/m²K for double glazing (Building Regulations, GOV.UK, 2026). FENSA installers check compliance with these thermal and ventilation requirements as part of the self-certification process (FENSA, 2026).
- Windows must meet minimum U-values (typically 1.4 W/m²K for double glazing)
- FENSA installers check compliance with thermal and ventilation requirements
8. Not all glazing work needs a FENSA certificate
Some types of glazing work are exempt from the requirement. Like-for-like repairs and secondary glazing do not need a FENSA certificate (GOV.UK, 2026). Also, listed buildings and properties in conservation areas may require separate listed building consent from your local planning authority rather than a FENSA certificate (Historic England, 2026).
- Like-for-like repairs and secondary glazing are exempt
- Listed buildings and conservation areas may require separate listed building consent
9. FENSA is one of several Competent Person Schemes
FENSA is the most well-known scheme for window and door installers, but it is not the only one. Other approved Competent Person Schemes include CERTASS, BBA, and BM Trada (GOV.UK, 2026). All of these schemes are equally valid for demonstrating Building Regulations compliance, so you are not limited to FENSA-registered installers alone.
- Other schemes include CERTASS, BBA, and BM Trada
- All are equally valid for Building Regulations compliance
10. You can check an installer’s FENSA registration before hiring
Before you agree to any work, you should verify that the installer is currently registered with FENSA or another Competent Person Scheme. You can use the FENSA website to check their current registration status (FENSA, 2026). If an installer is not registered, they cannot self-certify, meaning you would have to use your local building control department instead, which adds cost and delay. guide to choosing a window installer
- Use the FENSA website to verify current registration status
- Unregistered installers cannot self-certify, so you must use local building control
A FENSA certificate is a legal requirement that protects you from fines and makes selling your home straightforward. Always check your installer is registered before work begins, and keep the certificate safe once it arrives. guide to Building Regulations for home improvements
Frequently Asked Questions
A FENSA certificate is official proof that your replacement windows or doors meet UK Building Regulations. It is issued by a FENSA-registered installer after they self-certify the work, as explained by GOV.UK.
Yes, a FENSA certificate is a legal requirement for replacement windows and doors in England and Wales under Building Regulations. Without it, your local council can demand corrections or fines, according to GOV.UK.
A FENSA certificate typically costs nothing extra as it is included in the installer's fee. If you need retrospective approval from a local authority, it can cost £200–£400, as stated by the Energy Saving Trust.
Without a FENSA certificate, buyers' solicitors will flag it, and you may need to buy indemnity insurance or apply for retrospective building control approval. This can delay the sale and add costs, as noted by GOV.UK.
Yes, you can get retrospective building control approval from your local authority if the work was done without a FENSA certificate. This costs £200–£400 and may involve an inspection, according to the Energy Saving Trust.
