FENSA Certificate: A Stress-Free Sale Guide

A FENSA certificate is proof that replacement windows or external doors fitted in your home since April 2002 comply with UK Building Regulations. When you sell, your buyer's solicitor will ask for one for any glazing installed since then. If you have it, hand it over and the sale moves on. If you do not, you are not stuck — you can order a replacement copy from FENSA for about £30, apply to your council for a regularisation certificate (roughly £250–£500), or take out building-regulations indemnity insurance (often £30–£150). Missing paperwork rarely kills a sale, but sorting it early stops it becoming a last-minute panic.

What a FENSA certificate actually is

FENSA stands for the Fenestration Self-Assessment Scheme. It launched in April 2002, the moment replacement windows and doors came under the Building Regulations in England and Wales. The idea is simple: rather than every homeowner calling out building control every time they swap a window, an installer registered with FENSA can self-certify that the work meets the regulations and register it on your behalf. You get a certificate confirming compliance.

That certificate matters for two regulations in particular. One is thermal performance — modern replacement glazing has to hit a minimum energy-efficiency standard (the Part L requirements, currently a maximum U-value of 1.4 W/m²K for windows). The other is safety and escape: glass in critical locations must be toughened or laminated, and habitable rooms and certain bedrooms need a window that can act as a fire escape. FENSA registration says a competent installer has checked all of that.

Here is the thing people miss: FENSA is not a legal requirement in itself. The compliance is the legal requirement. FENSA is just the most common way to prove it. That distinction is what unlocks your options if the certificate is missing.

Why it matters when you sell

When your home goes under offer, the buyer's conveyancer runs through the standard enquiries. On the TA6 Property Information Form you complete, there is a direct question about replacement windows and whether you have the relevant certificates. If you tick "yes" but cannot produce the paperwork, expect the solicitor to come back and ask for it.

Why do they care so much about a window? Two reasons. First, if the glazing does not comply, the local authority has enforcement powers — in theory it can require unauthorised work to be put right. Second, and more practically, the buyer's mortgage lender wants a clean title with no loose ends. A missing FENSA certificate is a classic "loose end" that can hold up the lender's final sign-off. It is rarely fatal, but it is friction, and friction near completion is where deals wobble.

First check: do you even need one?

Not every window needs a FENSA certificate. Run through this quickly before you assume there is a problem.

• Fitted before 1 April 2002? No certificate needed — the regulations did not apply then. Original windows from the 1990s are fine as they are.
• Repaired rather than replaced? Replacing a broken pane or a handle in an existing frame is a repair, not a controlled installation. No certificate required.
• New-build or extension signed off under a full building control completion certificate? The windows were covered by that certificate. You do not need a separate FENSA document.
• Fitted by a CERTASS-registered installer instead? Then you have a CERTASS certificate, which is exactly as valid — see below.

If none of those apply and the windows went in after April 2002, you do need proof of compliance. So the next question is which route.

FENSA vs CERTASS vs building control — they all count

Sellers often panic because they were told "you need a FENSA certificate" when in fact they have a perfectly valid CERTASS one, or building control sign-off. All three prove the same thing. Do not let a buyer's solicitor imply that only FENSA counts — it does not.

Route to compliance	Who issues it	When it is created	Accepted on sale?
FENSA certificate	FENSA-registered installer	At time of installation	Yes
CERTASS certificate	CERTASS-registered installer	At time of installation	Yes — equally valid
Building control completion certificate	Local authority building control	After the council inspects the work	Yes
Regularisation certificate	Local authority (for past unauthorised work)	Applied for retrospectively	Yes
Building-regs indemnity insurance	Insurer	Any time (see conditions)	Usually accepted by lenders

So "I don't have a FENSA certificate" is not the dead end it sounds like. You might already have a CERTASS one in a drawer, or the work might pre-date the rules entirely.

You have lost the original — get a replacement first

Before you spend money on insurance or council fees, check whether the work was registered at all. If a FENSA-registered installer did the job, the record still exists in FENSA's database even if your paper copy has vanished. You can order a replacement certificate directly from FENSA.

The 2026 replacement fee is £30, paid online. A digital copy is usually emailed within about 24 hours; a posted physical certificate takes roughly 7 to 14 days. To find it, you can search the FENSA register by your address. If your installation shows up, a £30 replacement is by far the cleanest fix — it is a genuine compliance certificate, not a workaround, and no solicitor will quibble with it.

This is the step people skip, and it is almost always the right first move. Do not reach for indemnity insurance until you have confirmed the work was never registered in the first place.

How to check the FENSA register yourself in five minutes

You do not have to wait for a solicitor to tell you whether your windows are on record. FENSA runs a public register you can search by address, and it is the quickest way to know where you stand before you spend a penny.

• Search by your postcode and house number. If an installation comes up, note the date and the installer — that confirms the work was registered and a £30 replacement copy is available.
• Nothing found? That does not automatically mean the work was illegal. It may have been done by a CERTASS installer (check that scheme's records too) or signed off directly by building control. Dig out your completion paperwork or ask your conveyancer to check the local authority records.
• Still nothing anywhere? Now you know the work was genuinely unregistered, and you can move to indemnity insurance or regularisation with a clear head.

Doing this early turns a vague worry into a concrete fact, and a concrete fact is far cheaper to fix than a last-minute unknown. It also means that when the buyer's solicitor raises the question, you already have the answer ready — which is exactly the kind of thing that keeps a buyer confident and a chain calm.

No certificate exists — your two real options

If the work was genuinely never registered — a cash-in-hand fitter, a since-vanished company, or a DIY job — you have two routes. They suit different situations, and it matters which you pick.

Option 1: Indemnity insurance (fast and cheap)

Building-regulations indemnity insurance is a one-off policy that protects the buyer and their lender against the cost if the council ever takes enforcement action over the unauthorised windows. It is the quickest fix — a policy can be arranged in a day or two, and it typically costs somewhere between £30 and £150 depending on the property value. It lasts in perpetuity and passes to future owners.

Be clear about what it does and does not do. It does not prove the windows are safe or compliant. It simply insures against the financial fallout if enforcement ever happens. Most lenders accept it, which is why it is the go-to fix when a completion date is bearing down on you.

Two firm rules with indemnity insurance. First, you can usually only take a policy out if the installation was more than 12 months ago — councils lose most enforcement powers after a year, which is precisely why insurers are willing to cover it. Second — and this is the mistake that ruins the whole plan — do not contact the local authority about the windows first. The moment you approach the council, you invalidate the ability to buy indemnity cover, because the risk you are trying to insure against is no longer unknown. Decide your route before you pick up the phone.

Option 2: Council regularisation (slower, but genuine compliance)

A regularisation certificate is the local authority's formal sign-off on work that was done without approval at the time. You apply to building control, they inspect what was installed (which may mean exposing part of the frame or fitting so they can check it), and if it meets the standard they issue a certificate. This is real compliance, not just insurance against enforcement.

It costs more — typically £250 to £500 depending on the council and the number of windows — and it takes longer, often several weeks, because an inspection has to be arranged. But it is the honest, permanent answer, and some buyers (or their solicitors) prefer it to indemnity insurance because it removes the underlying problem rather than papering over it. If the windows are clearly good quality and you have time, this is the route I would lean towards. If you are racing a chain, indemnity insurance keeps things moving.

A worked example — what the missing certificate actually costs you

Picture a three-bed semi in Sheffield, on the market at £240,000. The sellers had the whole house re-glazed in 2016 by a local firm that has since gone bust, and the FENSA certificate never made it into their file. The buyer's solicitor raises it two weeks before exchange.

• Step 1 — search the FENSA register: no record found. The firm was not FENSA-registered. So a £30 replacement is off the table.
• Step 2 — decide the route: the chain is moving and the buyer wants to complete within the month. The sellers choose indemnity insurance rather than a multi-week council inspection.
• Step 3 — buy the policy: a one-off building-regs indemnity policy costs £85, arranged the same afternoon by their conveyancer. Crucially, they had not contacted the council, so cover was available.
• Outcome: the buyer's lender accepts the policy, the enquiry is closed, and the sale completes on time. Total cost: £85 and a couple of emails.

Compare that with the alternative timeline: sellers who ignore the enquiry, the buyer gets nervous, the lender flags the title, and two weeks of silence turns a minor admin point into a wobbling chain. Same £85 fix — but handled late, it costs stress and sometimes the buyer.

When the windows genuinely do not comply

Occasionally the problem is real: the glazing is old, the seals have failed, or a DIY job used the wrong glass in a critical location. In that case neither a replacement certificate nor indemnity insurance addresses the underlying issue honestly, and a regularisation inspection may fail.

If the windows are near the end of their life anyway, the cleanest answer can be to replace them properly through a FENSA-registered installer, who then issues a fresh, valid certificate — problem solved permanently. If you would rather not spend on a house you are leaving, price the property to reflect it and disclose honestly. Some buyers are perfectly happy to take on tired windows at the right price. And if the property has bigger issues than glazing — condition, a broken chain, a probate deadline — selling to a cash house buyer that takes the property as-is sidesteps the certificate question entirely, because these buyers are not relying on a high-street mortgage lender to sign off the title.

The honest balance: don't over-engineer a small problem

It is worth keeping perspective. In the great majority of sales, a missing FENSA certificate is a five-minute conversation and an £85 policy, not a deal-breaker. Councils very rarely pursue enforcement on domestic windows fitted years ago, and buyers' solicitors deal with this exact issue every week. The people who come unstuck are almost always the ones who leave it until the last moment or, worse, phone the council first and lock themselves out of the cheap insurance route.

Equally, do not go the other way and hide it. Ticking "no windows replaced" on the TA6 when you clearly had the whole house done is a misrepresentation that can come back on you after completion. Be straight, sort the paperwork early, and it stays a footnote.

What buyers' solicitors actually accept — and the timeline that matters

Conveyancers are not out to trap you. They deal with missing window certificates constantly, and they have a settled list of what satisfies them: a FENSA or CERTASS certificate, a building control completion or regularisation certificate, or an indemnity policy that the lender accepts. Provide any one of those and the enquiry is closed. What they cannot accept is silence, or a flat "I don't know", because that leaves the lender exposed.

The timeline is the part worth planning around. An indemnity policy can be arranged in a day. A replacement certificate takes up to a couple of weeks by post, though the digital copy is quicker. A council regularisation, because it needs a physical inspection, can take several weeks and occasionally longer if the council is busy. Line that up against a typical sale — 16 to 24 weeks on the open market from listing to completion — and you can see why the regularisation route only works if you start it early. Leave it until the enquiries stage and you are forcing yourself into the insurance option by default, which is fine, but it should be a choice rather than an accident.

One last practical point that saves sellers money: gather every scrap of glazing paperwork into a single folder the day you decide to sell — old invoices, guarantees, the FENSA or CERTASS certificate, any building control letters. Installer guarantees often name the scheme the firm belonged to, which tells you instantly where to look on the register. Buyers and their solicitors read a tidy, complete file as a sign the whole house has been looked after, and that goodwill is worth more than the paperwork itself when it comes to holding a sale together.

Frequently asked questions

Do I legally need a FENSA certificate to sell my house?

Not FENSA specifically. What you legally need is proof that replacement windows fitted since April 2002 comply with Building Regulations. A FENSA certificate is the most common proof, but a CERTASS certificate, building control completion certificate, regularisation certificate, or indemnity insurance can all satisfy the buyer's solicitor.

Can I get a FENSA certificate issued retrospectively?

No. A FENSA certificate is created at the time of installation by a FENSA-registered installer and cannot be issued after the fact. If the work was never registered, your routes are council regularisation or indemnity insurance instead. If it was registered and you have simply lost the copy, order a £30 replacement.

How much does it cost to fix a missing certificate?

A replacement copy of a registered certificate is about £30. Indemnity insurance typically runs £30–£150 as a one-off. A council regularisation certificate is usually £250–£500 plus the cost of any inspection. The right choice depends on whether the work was registered and how much time you have.

Should I contact the council if I have no certificate?

Not before you have decided your route. Approaching the local authority about unauthorised windows can invalidate your ability to take out indemnity insurance, which is often the cheapest and fastest fix. Speak to your conveyancer first and choose your approach before contacting building control.

Will a missing certificate stop my sale?

Rarely. It can slow a sale if left unaddressed, because the buyer's lender wants the title clean. But because indemnity insurance and replacement certificates are quick and cheap, most sales absorb the issue with minimal fuss — provided you deal with it early rather than the week of exchange.

Does indemnity insurance mean my windows are safe?

No. Indemnity insurance only protects the buyer and lender financially if the council ever takes enforcement action. It says nothing about whether the glazing meets the standard. If you want genuine compliance, a council regularisation inspection is the honest route.

The bottom line

A FENSA certificate is proof, not a hurdle. If you have it, selling is unaffected. If you have lost it, a £30 replacement usually settles the matter. If it never existed, indemnity insurance or council regularisation closes the gap for a modest sum — as long as you choose your route before you call the council. The only real failure here is delay: handled early, this is a footnote in your sale; handled late, it becomes the thing that spooks a nervous buyer.

If you are getting a property ready to sell and want to understand the wider picture — what your home is worth, how the process runs and where the genuine delays come from — start with our guides to how much your house is worth, the property jargon explained, and how to sell your house fast. Get the paperwork straight before you list and the sale itself has far fewer places to snag.

Ready Steady Sell is run by founder Lisa Hayes and helps UK homeowners sell with less stress and fewer surprises — including the small compliance details, like FENSA certificates, that trip up otherwise smooth sales. This guide is general information; check current fees with FENSA and your local authority, and take advice from your conveyancer on your specific sale.