FENSA Certificate: What It Is and How to Check Yours (2026)

A FENSA certificate is the document that proves your replacement windows or doors meet Building Regulations in England and Wales. It is issued when a FENSA-registered installer completes the job, logged on the FENSA register against your address, and asked for by solicitors whenever the home is sold.

FENSA comes up in every window replacement conversation, yet many homeowners are unsure what it covers, how to check a certificate, or what happens if an installer is not registered. Getting it right can save you money and legal headaches when you come to sell. Vitrum Solutions is FENSA registered, so every uPVC and aluminium window we fit is certified; you can request a free quote for your home.

What Does FENSA Stand For?

FENSA stands for Fenestration Self-Assessment Scheme. "Fenestration" simply means windows and doors. It is a government-authorised competent person scheme, set up by the Glass and Glazing Federation in 2002, that allows registered window and door installers to self-certify that their installations comply with Building Regulations, specifically Part L (conservation of fuel and power) and the safety glazing requirements now set out in Approved Document K.

In simple terms: when a FENSA-registered installer replaces your windows, they register the job with FENSA, which notifies your local authority on their behalf. You receive a FENSA certificate as proof of compliance, which is logged on the FENSA register and found by future buyers' solicitors through conveyancing searches.

When Did FENSA Certificates Come In?

FENSA certificates came in on 1 April 2002, when replacing windows and doors in England and Wales became controlled building work under the Building Regulations. Any replacement window or door fitted since that date needs either a FENSA certificate (or one from another competent person scheme) or a completion certificate from the council's building control team. Windows fitted before April 2002 do not need one.

How to Check a FENSA Certificate

The FENSA register is free to search and the check takes a couple of minutes. There are two different checks, depending on what you need.

Check a certificate for a property

Use this when you are buying a home, have lost your certificate, or want to confirm your installer registered the work:

• Open the Certificates page on fensa.org.uk
• Search by the property address, or by the certificate details if you have them
• If a certificate is found, you can order a copy online for a fee, paid by card

If nothing comes up, FENSA gives three possible reasons: the address or postcode was entered incorrectly, the job included more than replacing windows and doors, or the installer never notified FENSA when the work was finished. FENSA's Help Centre can advise on the next step.

Check that an installer is FENSA registered

Use this before you sign a contract:

• Visit fensa.org.uk and use the installer search
• Enter the company name or registration number
• The search confirms whether they are currently registered and in good standing

What Does a FENSA Certificate Look Like?

A FENSA certificate is a formal document that includes:

• The property address
• The installer's FENSA registration number
• The date of installation
• A description of the work carried out (number and type of windows or doors replaced)
• Confirmation of Building Regulations compliance
• A unique certificate reference number

The certificate is sent to you by post and email within approximately 20 working days of the installation being registered. A copy is also sent to your local authority's building control department and the record sits on the FENSA register.

How Long Does a FENSA Certificate Last?

A FENSA certificate does not expire. It is a permanent record that the installation complied with Building Regulations at the time it was carried out, and it stays with the property when you sell. The insurance-backed guarantee issued alongside it is a separate document; ours runs for 10 years.

FENSA Replacement Certificate: If Yours Is Lost

Lost certificates are common, and they usually surface during a sale when the buyer's solicitor asks for them. You do not need to contact the original installer. Search the property address on the FENSA Certificates page as above and order a replacement copy online; it is sent by email. If you need certificates for several jobs at the same address, each installation has its own record.

Why Does FENSA Exist?

Replacement windows and doors must meet minimum standards for:

• Energy efficiency: in England, replacement windows must achieve a U-value of 1.4 W/m²K or better, or a Window Energy Rating of band B or better
• Safety glazing: glass in critical locations (doors, low-level panels, windows near floor level) must be toughened or laminated
• Ventilation: habitable rooms must maintain adequate background ventilation, typically through trickle vents
• Means of escape: bedroom windows must open far enough to serve as a fire escape

Before competent person schemes existed, homeowners had to apply to their local council for building regulations approval before replacing windows, which meant inspection visits and fees. FENSA streamlines this by letting competent installers self-certify, so the council does not need to inspect.

Other Double Glazing Certificates

FENSA is the best-known scheme but not the only one. The government authorises several competent person schemes for replacement windows and doors. Besides FENSA, the others on the GOV.UK list are Certass, Assure Certification, NAPIT, Certsure and Blue Flame Certification.

A certificate from any of them proves Building Regulations compliance just as a FENSA certificate does, and all are equally valid for a sale. If your windows came with a Certass certificate rather than a FENSA one, nothing is missing; check it on that scheme's own register instead.

What Happens Without a FENSA Certificate?

This is where FENSA matters most. If your windows were replaced without a FENSA certificate (or equivalent building regulations approval from the local authority), several problems arise.

When selling your home

Conveyancing solicitors routinely check for building regulations compliance certificates for any replaced windows. If certificates are missing, the solicitor will flag it, and the buyer's solicitor may:

• Ask you to obtain retrospective approval from the local authority (called a regularisation certificate), which involves an inspection and a council fee (check the current charge with your local authority's building control team)
• Ask for an indemnity insurance policy to cover the buyer against potential enforcement action, paid as a one-off premium
• Use the missing certificates as a negotiating point to reduce the price
• In extreme cases, advise the buyer to withdraw from the sale

Building regulations enforcement

Local authorities can serve a notice requiring non-compliant work to be altered or removed. Since April 2024, under changes made by the Building Safety Act 2022, that notice can be served up to 10 years after the work was completed, so uncertified windows remain a risk for much longer than they used to.

Insurance implications

Some home insurance policies expect building work to be properly certified. A non-certified installation could complicate a claim connected to the windows, for example a break-in through a non-compliant window, or water damage from incorrectly installed units.

No insurance-backed guarantee

FENSA-registered installers must provide an insurance-backed guarantee (IBG) on every installation. Without a registered installer you will not automatically receive one, so if the company goes bust you have no guarantee protection. How the guarantee works, what it leaves out and how to claim on it are set out further down this guide.

Red Flags When Choosing an Installer

• "We don't bother with FENSA." The installation will not be legally certified. Walk away.
• "We'll sort the certificate later." A registered installer notifies FENSA as a matter of routine once the job is finished. Vagueness here can mean they are not registered.
• "You can get a certificate from the council instead." Technically true, but you then pay the council's building control fee for an inspection that a registered installer would cover as standard.
• Very low prices. Installers far cheaper than competitors may be cutting costs by avoiding scheme registration and the compliance that goes with it.

FENSA and Energy Efficiency

One of FENSA's core functions is making sure replacement windows meet minimum energy standards. In England, a replacement window must meet one of two routes:

• U-value route: a whole-window U-value of 1.4 W/m²K or better
• Energy rating route: a Window Energy Rating of band B or better

Glazed doors more than 60% glazed need 1.4 W/m²K or a Door Set Energy Rating of band C; other doors need 1.4 W/m²K or band B. In practice, modern windows from reputable systems comfortably meet these standards. For example:

• Rehau TOTAL70 uPVC windows can achieve an A+ rating
• Cortizo Cor 70 Hidden Sash aluminium windows achieve a Uw from 0.84 W/m²K
• Schuco AWS 70.HI aluminium windows have a frame U-value (Uf) from 1.6 W/m²K, with the whole-window figure confirmed for your glazing at survey

The energy requirement is one reason FENSA registration matters: it ensures your windows genuinely cut heat loss, which helps your EPC rating and long-term energy bills.

FENSA vs Building Control

If your installer is not registered with FENSA or another competent person scheme, you must use the local authority building control route instead. Here is how they compare:

• Cost to homeowner: FENSA is included in the installation; building control means a council fee paid by the homeowner.
• Inspection: with FENSA the installer self-certifies; with building control a council inspector visits during and after installation.
• Timeline: a FENSA certificate arrives within about 20 working days; building control can take several weeks including inspection scheduling.
• Insurance-backed guarantee: required and included with FENSA; not included with building control, so you must arrange it separately.
• Convenience: with FENSA the installer handles everything; with building control the homeowner must apply and coordinate inspections.

For most homeowners, a FENSA-registered installer is simpler, cheaper, and gives better protection through the mandatory insurance-backed guarantee.

FENSA Guarantee: How to Claim on an Insurance-Backed Guarantee

The insurance-backed guarantee sits behind the installer's own workmanship guarantee. While the installer is trading, a fault goes to them first. The insurance steps in when the installer has ceased trading, and the claim then runs through four steps.

Step 1: Confirm the installer has ceased trading

Look the company up on Companies House (find-and-update.company-information.service.gov.uk) to confirm it is dissolved or in administration. The guarantee provider will usually check this before it processes a claim.

Step 2: Contact the guarantee provider

Call or email the provider named on your guarantee certificate. Have ready:

• Your guarantee certificate or policy reference number
• The property address
• A description of the fault
• Photographs of the problem, where they help

Step 3: Assessment

The provider will usually assess the fault, often with a site visit, to confirm it is an installation defect covered by the guarantee rather than wear and tear or accidental damage.

Step 4: Repair

Once a claim is approved, the provider settles it under the terms of the policy, typically by arranging the remedial work. Your certificate sets out exactly how your provider handles this.

How long a claim takes

A claim moves through acknowledgement, the assessment visit, the decision and then the repair, so allow weeks rather than days from first contact to a finished job. The claim procedure on your certificate sets out the provider's own steps and contact details. If the fault leaves the home insecure or letting in water, say so when you first make contact.

What the Guarantee Does Not Cover

Knowing the limits matters as much as knowing the cover. Policies differ, so check your own certificate, but an insurance-backed guarantee typically does not pay for:

• Faults in the products themselves. Glass, hardware and profile are covered by the manufacturer's terms, which vary by system. Vitrum Solutions confirms them in writing with every quote.
• Fair wear and tear. Hinges, handles and locks that wear through years of normal use.
• Accidental or user damage. Impact damage, forced locks or slammed doors.
• Damage from later building work. An extension or new render that damages the windows after they were fitted.
• Condensation on the room side of the glass. That is a ventilation issue rather than a defect.

How Vitrum Solutions Handles FENSA

Every window and door installation we carry out is FENSA certified. It is a fundamental part of our service, and here is what it means for you:

• We register every installation with FENSA within 5 working days of completion
• You receive your FENSA certificate by post and email within 20 working days
• A copy goes to your local council automatically, with no action required from you
• Every installation includes an insurance-backed guarantee from the Consumer Protection Association (CPA), covering you for 10 years even if our company ceases trading
• All our installations meet or exceed current Building Regulations for energy efficiency, safety glazing and ventilation

Whether you are installing uPVC casement windows, aluminium bifold doors or composite entrance doors, FENSA certification is included in every quote with no additional charge.

Frequently Asked Questions

Is FENSA a legal requirement?

FENSA is one of several approved routes to show Building Regulations compliance, not the only one. Building Regulations compliance itself is a legal requirement for all replacement window and door installations in England and Wales, and using a FENSA-registered installer is the simplest way to achieve it.

Can I install windows myself and get a FENSA certificate?

FENSA certificates can only be issued by registered installation companies. If you install windows yourself, you must apply to your local authority for a building regulations completion certificate through the building control route, which involves an inspection and a fee.

What if I bought a house and the windows don't have FENSA certificates?

First search the address on the FENSA register and the other scheme registers, because the certificate may simply have been lost. If the windows were replaced after 1 April 2002 and no certificate exists, you have two options: obtain a retrospective regularisation certificate from the local authority (the council charges a fee and inspects the work), or buy an indemnity insurance policy that covers you and future buyers against enforcement action.

How long does a FENSA certificate last?

A FENSA certificate does not expire. It is a permanent record that the installation was compliant when it was carried out. The insurance-backed guarantee issued with it typically lasts 10 years.

Do I need FENSA for a single window replacement?

Building Regulations apply to every replacement window or door, however many are being replaced. Even a single window replacement in England and Wales needs either a competent person scheme certificate such as FENSA or building control approval.

Does the insurance-backed guarantee transfer if I sell my home?

The guarantee is issued for the installation at your property and runs for 10 years. The transfer terms sit in the policy wording on your certificate, so read them before you sell. Either way, hand the guarantee certificate to your buyer with the FENSA certificate, because their solicitor will ask to see both.