FENSA Register: What Homeowners Need to Check
If you are replacing windows or doors in your home, you will hear the word FENSA mentioned early in the conversation. The FENSA register is the official record of certified window and door installations across England and Wales, and the certificate that comes with it is something you will need when you come to sell your property. This guide explains exactly what FENSA is, how to check the register, and what to do if the work on your home was never certified.
What Is FENSA?
FENSA — the Fenestration Self-Assessment Scheme — was established in 2002 by the Glass and Glazing Federation and approved by the government as a competent person scheme. Its purpose is straightforward: to allow registered window and door installers to self-certify that their work meets building regulations, without the homeowner needing to separately apply to the local authority building control department.
Before 2002, if you replaced a window, the work technically required building control sign-off to confirm it met energy efficiency and structural requirements. In practice, almost nobody applied, and compliance was rarely checked. FENSA was created to change that — giving the industry a self-regulation mechanism and homeowners a clear paper trail.
Today, any company that replaces windows or doors in England or Wales should either be registered with FENSA (or an equivalent scheme such as CERTASS) or the homeowner should use local authority building control instead.
What Does FENSA Cover?
FENSA certification applies to replacement windows and doors in existing dwellings. Specifically:
- Replacement of existing windows (including roof windows and skylights)
- Replacement of external doors
- Replacement of roof windows in existing roofs
It covers compliance with Part L of the building regulations (thermal performance — the window must meet minimum U-value standards) and certain structural and safety requirements.
FENSA does not cover:
- New build properties (covered by building control separately)
- Windows in extensions (require planning permission or permitted development compliance and building control)
- Windows in listed buildings (which require Listed Building Consent regardless of the glazing specification)
- Structural changes to window openings (enlarging or moving an opening requires building control)
If you are in a listed building and having windows replaced, FENSA is not the relevant mechanism. You will need to obtain consent from your local planning authority, and the work may need to be inspected by building control or your conservation officer.
Why Do You Need a FENSA Certificate?
There are two main reasons the FENSA certificate matters.
First, it is a legal requirement. Building regulations apply to replacement windows and doors. The FENSA certificate is evidence that the work complies. Without it, you or your contractor are potentially in breach of building regulations.
Second, you will need it when you sell your home. When you instruct a solicitor to sell your property, they will carry out searches and enquiries that include asking for evidence of building regulations compliance for any work done since 2002 that required it. If you replaced windows — at any point since 2002 — and cannot produce a FENSA certificate or a local authority completion certificate, your solicitor will flag this as a defect.
At that point, you have two options: obtain a retrospective Local Authority Building Control certificate (which requires an inspection and takes time and money) or take out indemnity insurance. Neither option is as straightforward as simply having the certificate in the first place. This situation is very common with properties where windows were replaced by an unregistered trader — often in the mid-2000s uPVC boom — and no paperwork was ever issued.
How to Check the FENSA Register
The FENSA register is publicly accessible at fensa.org.uk. You can use it in two ways.
To check whether a specific installation is registered:
- Go to fensa.org.uk and click 'Check a Certificate'
- Enter the property postcode
- The search returns any FENSA-registered installations at that address, including the date, installer and certificate number
- You can download a copy of the certificate from the same page
This is useful if you are buying a property and want to verify that window replacement work was properly certified, or if you are a homeowner who has misplaced your original certificate.
To check whether an installer is FENSA registered:
- Go to fensa.org.uk and click 'Find an Installer'
- Search by company name, postcode or registration number
- The result confirms whether the company is currently registered and in good standing
Always verify this before instructing a window installer. A FENSA-registered company's registration number will appear on their website, their quote documents and their invoice. If a company tells you they are FENSA registered but cannot produce a number, be cautious.
What If My Windows Were Not FENSA Certified?
If window replacement work was done at your property without FENSA certification — or without any building control involvement — you have several options.
Retrospective Local Authority Building Control (LABC) certificate. You can apply to your local building control department for a regularisation certificate. This involves a formal application, a fee (typically £150-£300 depending on the council) and an inspection. If the work is found to comply, a certificate is issued. If it does not comply — because the windows are below the required thermal standard — you may be required to upgrade or replace them to obtain the certificate.
Indemnity insurance. If the windows cannot easily be inspected or if regularisation is impractical, solicitors sometimes accept an indemnity insurance policy that covers any future local authority enforcement action. This is a common workaround at the point of sale, but it does not fix the underlying compliance issue.
Replacement. If the windows are now old, non-compliant or in poor condition, replacing them with properly certified new windows is often the most practical solution. The new installation will be FENSA-certified and the historical issue disappears.
FENSA vs Local Authority Building Control
These are two routes to the same destination — demonstrated compliance with building regulations for replacement windows.
FENSA
Local Authority Building Control
Who certifies
Registered installer (self-certification)
Local authority inspector
Timing
Certificate issued after installation
Application before work; inspection after
Cost to homeowner
Included in installer's price
Fee payable to local authority
Suitable for
Standard replacement windows and doors
Structural changes; new openings; listed buildings
For a straightforward window replacement in an ordinary residential property, FENSA is almost always the simpler and faster route. The LABC route is appropriate when the scope of work goes beyond straightforward replacement, or when a homeowner prefers independent building control oversight.
Frequently Asked Questions
Does every window replacement need FENSA?
Every replacement window in England or Wales must comply with building regulations. FENSA is one route to demonstrating that compliance — the other is local authority building control. In practice, almost all standard residential replacement windows are handled through FENSA.
Every replacement window in England or Wales must comply with building regulations. FENSA is one route to demonstrating that compliance — the other is local authority building control. In practice, almost all standard residential replacement windows are handled through FENSA.
Can I check if my existing windows are FENSA certified?
Yes — use the Check a Certificate tool at fensa.org.uk and enter your postcode. If the installation was registered, the details will appear. If nothing comes up, the work may have gone through local authority building control instead, or it may never have been certified.
Yes — use the Check a Certificate tool at fensa.org.uk and enter your postcode. If the installation was registered, the details will appear. If nothing comes up, the work may have gone through local authority building control instead, or it may never have been certified.
What if I am in a listed building or conservation area?
FENSA does not apply to listed buildings — those require Listed Building Consent for any alteration to windows. If you are in a conservation area but not in a listed building, FENSA may still apply to replacement work, but you should check with your local planning authority whether an Article 4 Direction or other restriction applies before proceeding.
FENSA does not apply to listed buildings — those require Listed Building Consent for any alteration to windows. If you are in a conservation area but not in a listed building, FENSA may still apply to replacement work, but you should check with your local planning authority whether an Article 4 Direction or other restriction applies before proceeding.
Working with a FENSA-Registered Installer
AMB Joinery is FENSA registered. Every replacement window we install in England and Wales is certified, and you will receive your FENSA certificate within 30 days of completion. Find out more about our approach to FENSA-compliant window installation or contact us to arrange a free survey.
