A FENSA certificate is one of the documents most often requested by a buyer’s solicitor – and one of the most often missing. If you have replaced windows or doors, are buying a home where someone else did, or have just been asked for one by a conveyancer, this 2026 guide explains exactly what a FENSA certificate is, when you legally need one, how to check for and replace one, and what your options are if the paperwork simply does not exist. It draws on GOV.UK guidance, the Building Regulations themselves and the newly published 2026 edition of Approved Document L, with input from the suitably qualified, accredited surveyors on the Survey Merchant panel.
A FENSA certificate is a compliance document issued after replacement windows, doors or roof windows are fitted in an existing home in England or Wales. It confirms the installer was FENSA-registered, the work met Building Regulations (including thermal performance, ventilation and safety glazing), and the installation was registered with your local authority.
FENSA stands for the Fenestration Self-Assessment Scheme. According to FENSA’s own history, it was created in April 2002, when Building Regulations were extended to cover replacement glazing, and it describes itself as the first Competent Person Scheme for the window and door industry. By 2018 it reported more than 13 million certificates issued. Because it has been around the longest, “FENSA certificate” has become shorthand for any window compliance certificate – but, as we explain below, it is not the only valid one.
Strictly speaking, no – but compliance with the Building Regulations is. Since April 2002, replacing windows, doors, roof windows or roof lights in a dwelling has been “notifiable” work in England and Wales. GOV.UK’s guidance on replacements and repairs to your home is clear: the work must be notified to a Building Control Body unless it is carried out by an installer registered with a Competent Person Scheme.
There are therefore two lawful routes:
So a FENSA certificate is one of several acceptable proofs. What a solicitor, lender or surveyor actually wants is evidence that notifiable work was signed off by someone entitled to sign it off.
FENSA only covers the replacement of windows and doors in existing homes. It does not cover new-build glazing, which is inspected as part of the whole-house building control process, nor work that is already dealt with under a wider building regulations application. The table below sets out the most common scenarios.
| Scenario | FENSA (or equivalent scheme) certificate? | Notes |
|---|---|---|
| Replacing windows in an existing house or flat | Yes | Notifiable since April 2002; scheme certificate or building control sign-off needed. |
| Replacing an external door or doorset | Yes | Includes front, back, patio and bi-fold doors. |
| Replacing roof windows or roof lights | Yes | Covered by the same GOV.UK notifiable list. |
| Windows in a new-build home | No | Covered by the overall building control completion certificate. |
| Windows in a new extension | No (separately) | Checked under the extension’s building regulations application. |
| Conservatory or porch under 30 m² that is exempt | Usually no | Exempt structures are outside FENSA; check the exemption conditions carefully. |
| Repairing a window (new glass unit, hinges, handles) | No | Repairs are not notifiable; full frame replacement is. |
| Property in Scotland or Northern Ireland | No | FENSA operates in England and Wales only; separate building standards apply. |
It is worth understanding what the certificate does and does not say, because it is frequently over-read. A FENSA certificate confirms that, on the installation date, a registered installer self-certified the work as compliant with the relevant parts of the Building Regulations. For replacement glazing in an existing dwelling the key requirements are:
Crucially, the certificate is a declaration by the installer, not an independent inspection. It is not a guarantee of workmanship, nor a statement that the units are still performing years later. Blown (misted) sealed units, failed trickle vents and poor sealing are all things a house survey will pick up regardless of what paperwork exists.
You can search for and order a copy of any FENSA certificate through FENSA’s certificate service, either by property address and postcode or by the details on an existing certificate. If a search returns nothing, it usually means one of three things:
FENSA also states that it verifies every registered installer’s guarantee is insured, so the FENSA record can be useful if the original installer has since ceased trading.
If you use a FENSA-registered installer, the certificate is included in the price of the job – there is no separate fee to the homeowner. GOV.UK’s guidance states that if you have not received a certificate within 30 days of completion you should contact the Competent Person Scheme operator your installer is registered with. A replacement copy currently costs £30 including VAT when ordered online from FENSA.
| Item | Typical cost (2026) | Typical timescale |
|---|---|---|
| Original FENSA certificate via registered installer | Included in installation price | Should arrive within 30 days of completion (GOV.UK) |
| Replacement FENSA certificate | £30 inc. VAT (FENSA online service) | Days to a few weeks, depending on postal delivery |
| Building notice / full plans route (non-registered installer) | Local authority fee – varies by council and job size | Inspection during the work; certificate after sign-off |
| Regularisation certificate for unnotified work | Council fee, typically higher than a standard application; plus any opening-up or remedial work | Weeks to months |
| Indemnity insurance policy | One-off premium; Homebuilding & Renovating quotes a typical £80–£500 range | Usually arranged within days by the seller’s solicitor |
Costs other than FENSA’s published fee vary by council and insurer, so treat them as indicative and obtain quotes.
Buyers often panic when a seller produces a CERTASS certificate rather than a FENSA one. There is no need. Both are government-authorised Competent Person Schemes listed by GOV.UK for exactly this work, and a certificate from either carries the same legal weight. A building control completion certificate is equally valid – and, because it follows an inspection by the local authority or an approved inspector rather than installer self-certification, some surveyors regard it as the more robust document of the three.
| Route | Who certifies? | Council notified? | Independent inspection? | Insurance-backed guarantee? |
|---|---|---|---|---|
| FENSA | Registered installer (self-certification) | Yes, via scheme | Scheme audits a sample of jobs | Yes – FENSA checks installers’ guarantees are insured |
| CERTASS / Assure / other schemes | Registered installer (self-certification) | Yes, via scheme | Scheme audits a sample of jobs | Typically yes; check the scheme |
| Local authority building control | Building Control Body after inspection | Yes – direct application | Yes | No – separate warranty needed |
This is the question that generates most of the stress around FENSA, so let us be precise. Missing paperwork does not make a sale impossible, and it does not automatically mean the windows are unsafe or non-compliant. It does mean the buyer has no evidence of compliance, and the local authority retains enforcement powers. Here are the realistic options.
Many “missing” certificates were never missing: they were issued under CERTASS, are sitting on the FENSA database under a previous owner’s name, or were never posted. A quick search of the scheme databases and a call to the installer resolves a surprising number of cases.
Under regulation 18 of the Building Regulations 2010, the owner of a building can apply to the local authority for a regularisation certificate for unauthorised work carried out on or after 11 November 1985. The council may require you to lay the work open for inspection, carry out tests or take samples, and will issue the certificate once satisfied that the relevant requirements are met or that no further work is needed. The regulation describes the certificate as evidence – though “not conclusive evidence” – of compliance. Our detailed guide to the regularisation certificate process covers fees and pitfalls. For replacement windows, the inspector will typically want to see the units’ energy rating labels or manufacturer data, trickle vents, safety glazing marks and the condition of lintels.
The most common fix in a sale is a building regulations indemnity policy, paid for by the seller. It protects the buyer (and lender) against the financial cost of enforcement action by the local authority. It does not pay to fix defective windows, and policies are usually invalidated if anyone contacts the council about the work – so do not apply for regularisation and buy indemnity cover for the same work. Lenders generally accept a policy for older installations. See our explainer on when indemnity insurance is appropriate.
Historically a local authority had only 12 months after completion to serve a notice under section 36 of the Building Act 1984 requiring non-compliant work to be removed or altered. Section 39 of the Building Safety Act 2022 amended that period to 10 years and strengthened the penalties for contravening building regulations. In practical terms, buyers in 2026 should treat recent unnotified window replacements with more caution than they might have a few years ago, and sellers should expect solicitors to press harder for proper evidence.
Where the units are at the end of their life anyway – misted double glazing, rotten timber subframes, no trickle vents – it can be more sensible to negotiate a price reduction and replace them using a registered installer, which produces a fresh certificate and a new guarantee. A survey gives you the evidence to negotiate the house price after your survey.
Yes. There is no legal bar on selling, and the TA6 Property Information Form simply asks the seller to disclose whether windows have been replaced since April 2002 and to supply any certificates. If you cannot, say so honestly; your solicitor will usually offer an indemnity policy, and the buyer may accept it, request a regularisation certificate, or ask for a price adjustment. Mis-stating the position on the TA6 is far riskier than admitting the certificate is missing. Our guide to what a conveyancer does explains where this fits in the sale process.
A FENSA certificate tells you about the day of installation; a survey tells you about today. Whether you commission a Level 2 or Level 3 survey, a suitably qualified, accredited surveyor will typically:
Survey Merchant’s panel includes surveyors regulated or accredited by bodies such as RICS, CIOB and RPSA, matched to the type of survey you need. Whichever route you take, use a suitably qualified, accredited surveyor rather than relying on paperwork alone.
Three developments matter for anyone dealing with window compliance this year:
A FENSA certificate answers one narrow question. A good survey answers the ones that actually affect your money: are the windows sound, is there damp or ventilation trouble behind them, and what will it cost to put right? Survey Merchant helps you get that answer quickly and at a fair price.
Ready to find out what your windows – and the rest of the property – are really like? Explore our building surveying services or contact Survey Merchant for a fixed-fee quote today.
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