A FENSA certificate is the official proof that your replacement windows or doors meet Building Regulations and were installed by a registered professional. We explain exactly what a FENSA certificate is, when you need one, how to check or replace yours, and how it applies to loft conversions.
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A FENSA certificate is an official document that confirms your replacement windows or doors were fitted by a registered installer and meet current Building Regulations. FENSA stands for the Fenestration Self-Assessment Scheme, a government-authorised body set up in April 2002 to improve standards in the window and door industry.
When an approved installer replaces your windows or external doors, they self-certify the work through FENSA. You then receive a simple digital or printed certificate proving the installation meets thermal performance rules, safety glazing requirements and ventilation standards. It also confirms the work was notified to your local authority, so you don’t need a separate Building Control inspection.
It is important to note that a FENSA certificate only applies to replacement windows and doors. You do not need one for:
It also isn’t a product warranty. It’s purely proof of Building Regulations compliance. Most homeowners file the certificate with their property documents, as solicitors will ask for it if you sell your home. If your installer was FENSA-registered at the time, you’ll always be able to request a re-issue if you misplace it. On this page we cover:
A FENSA certificate confirms that your replacement windows or external doors were installed correctly and comply with Building Regulations. It shows that the work was carried out by a registered installer and has been officially recorded without needing a separate inspection from your Local Authority Building Control team.
Here is what a FENSA certificate covers:
You only need a FENSA certificate when replacing windows or exterior doors in your home. In these cases, the certificate acts as official proof that the installation meets Building Regulations and was carried out by a registered installer. If you are unsure whether your glazing work requires certification, the points below explain the situations where a FENSA certificate is essential.
If you remove old windows or external doors and install new ones in the same openings, the work must comply with Building Regulations. A FENSA certificate is the simplest way to prove this, as the installer self-certifies the work.
Only installers who are part of the FENSA scheme can issue a certificate. Once the job is completed, the certificate is generated automatically and sent to you.
Solicitors will ask for a FENSA certificate for any replacement glazing fitted after April 2002. Without it, the sale may be delayed while you provide proof or arrange indemnity insurance.
The certificate confirms compliance with rules on energy efficiency, ventilation, safety glazing and structural performance, giving you clear documentation for future reference.
Not all window installations require a FENSA certificate. New openings created as part of a loft conversion, extension, or new build fall under Building Control, and some types of glazing work are exempt from certification entirely. The list below explains the most common scenarios where a FENSA certificate is not needed, so you can understand exactly which rules apply to your project.
If your windows or doors were replaced after April 2002, there is a good chance a FENSA certificate already exists. The easiest way to check is through the official FENSA online search tool, which lets you look up previous installations linked to your property. The process takes less than a minute and gives you clear confirmation of whether a certificate is on record.
Visit the FENSA certificate search tool and enter your house number and postcode. The system will scan the national database for any registered replacement window or door installations at your address.
If a certificate exists, the search results will show:
This provides full proof that the glazing was installed correctly and officially recorded. If your property does not appear in the search: There are a few common reasons why no result shows:
If no certificate is listed, you can still prove compliance by locating your Building Control completion certificate or contacting your local council for records.
If you’ve lost your FENSA certificate, or you’ve moved into a property and need proof that past window replacements met Building Regulations, you can order a replacement directly through FENSA. The process is simple, affordable and available even if you were not the homeowner at the time of installation.
A replacement certificate costs £25 including VAT (price correct at the time of writing). It is issued digitally, though some homeowners request a printed copy for their records. Before ordering, it’s important to understand that a replacement can only be provided if the original work was carried out by a FENSA-registered installer. If no FENSA record exists, you will need to rely on Building Control records instead.
Below is the full step-by-step process to follow to ensure you seamlessly get a replacement.
Go to the official FENSA Certificate Search tool on the FENSA website. This is the only place where you can access the national FENSA certificate database. The system covers all compliant replacement window and door installations in England and Wales since April 2002.
Type in your house number and postcode exactly as they appear on your property details. The search tool will scan the FENSA database and return all matches for your address. If your property has changed from a house to flats (or vice versa), try any earlier versions of the address as well.
If your address has a FENSA record, you will see details such as:
A button will appear allowing you to order a replacement certificate. You do not need proof of ownership; buyers, sellers, landlords and new occupants can all request duplicates.
You will be taken to a secure checkout, a replacement certificate currently costs £25 including VAT. Payment is made online using a debit/credit card and once paid, the certificate is issued automatically. Prices occasionally change, so it is good practice to check the exact cost on the FENSA website before ordering.
Most replacement FENSA certificates are emailed to you within minutes. Some installers may also provide the option of a printed copy sent by post, although this is less common.
You should save the certificate with your house documents, as you will need it if you ever sell the property.
You cannot get a genuine FENSA certificate retrospectively. FENSA certificates are only issued at the time the work is completed, and only when the installer was FENSA-registered and has notified the installation through the scheme.
If the installer did not register the job at the time, or if they were not part of FENSA, no certificate can be created afterwards. However, you can still prove compliance in other ways.
If the original installer was registered and correctly notified of the work, you can order a replacement certificate from the FENSA website. This is not retrospective; it is simply a re-issue of an existing record.
In this case, FENSA cannot help. Instead, you will need to rely on one of the following:
In most cases, no. Loft conversions are assessed under full Building Regulations, which means any new windows installed as part of the conversion are inspected and signed off by Building Control, not FENSA.
This applies to Velux roof windows, dormer windows and any new structural openings created during the build. Building Control checks everything from fire escape compliance and safety glazing to thermal efficiency, insulation and structural integrity, so the glazing is already certified through this process. A FENSA certificate only applies to replacement windows in existing openings, which is why it is rarely needed for loft conversions.
Although loft conversions themselves do not usually require a FENSA certificate, there are situations where FENSA remains relevant within the same project. If you replace existing windows elsewhere in the house while the loft work is underway, those replacements fall under FENSA rather than Building Control.
This includes swapping out old frames for new double glazing on lower floors, upgrading bedroom windows unrelated to the loft structure, or replacing non-fire-escape windows that are not part of the new loft space. You may also need a FENSA certificate if you replace windows yourself without arranging a Building Control inspection, or if your loft company brings in a FENSA-registered installer to update older windows separately from the conversion.
As a simple rule, if the window was newly installed as part of the loft build, Building Control will sign it off; if the window was replaced outside the scope of the loft conversion, FENSA may apply.
When selling a property, buyers and solicitors will almost always ask for proof that any window replacements complied with Building Regulations. This is routine and applies even if the glazing work happened many years ago. If your home has a loft conversion, you may have Building Control sign-off for the new loft windows, but no FENSA certificates for older replacement windows elsewhere in the house. This is a common situation and can be resolved in several ways.
A buyer is mainly looking for reassurance that the work was lawful and safe. If you cannot provide a FENSA certificate, you can still supply alternative documentation that satisfies most conveyancers:
If you are replacing windows or completing a loft conversion, it helps to understand how FENSA applies. These quick answers cover the most common homeowner questions, from guarantees to Velux windows and the difference between FENSA and Certass.
No. A FENSA certificate is not a warranty or guarantee. It is proof that your replacement windows or doors met Building Regulations on the day they were installed and that the work was notified to your Local Authority.
Most FENSA installers must provide a separate insurance-backed guarantee, issued by the installer’s insurer, not FENSA itself.
Certass and FENSA are both government-authorised competent person schemes for replacement windows and doors. They perform the same role:
If your installer is Certass-registered rather than FENSA-registered, you will receive a Certass certificate rather than a FENSA certificate. Both are equally valid for selling a home or proving compliance.
Usually not. Loft conversions are signed off through Building Control, which inspects all new structural openings, roof windows, fire escape glazing, insulation and thermal performance. New Velux windows, dormer windows and structural openings created during the loft build are covered by this process, so a FENSA certificate is not required.
Velux or rooflight windows fitted as part of a loft conversion or extension do not need FENSA certification because they are included in the Building Control inspection.
However, if you simply replace an existing Velux window in the same opening outside a loft conversion project, and the installer is FENSA-registered, the replacement may fall under FENSA rules.
