Most people shopping for new doors focus on style, material, security and price. FENSA rarely features in the decision until something goes wrong: a certificate is missing, a property sale stalls, or a building inspector flags unregistered work. 

This guide exists to prevent that. It explains what FENSA is, which door types require certification, and what the rules mean for homeowners, landlords and contractors across the UK.

What Is FENSA?

FENSA (Fenestration Self-Assessment Scheme) is a government-authorised Competent Person Scheme (CPS) established in April 2002 to regulate the replacement of windows, doors and roof products in residential properties. It operates across England, Wales, Scotland and Jersey. Over 13 million FENSA certificates have been issued since 2002, covering more than 50% of all UK homes.

The scheme allows FENSA-approved installers to self-certify compliance with Building Regulations on behalf of their customers. This removes the need for homeowners to seek separate approval from Building Control before work starts, provided the installer they choose holds current FENSA approval.

FENSA is operated by FENSA Ltd, a company authorised by the UK Government and part of the GGF Group (Glass and Glazing Federation). Its registered office is 40 Rushworth Street, London, SE1 0RB.

What Does FENSA Cover?

FENSA covers the replacement of external doors, external windows, roof windows and roof lights in existing residential dwellings under 18 metres in height in England and Wales. The property must sit on its original footprint, and the use or size of rooms must not be altered by the work.

What Is in Scope

• Replacement external windows (all materials, not only uPVC)
• Replacement external doors (including glazed and partially glazed types)
• Replacement roof windows
• Replacement roof lights

What Is Out of Scope

The following types of work cannot be self-certified under FENSA, according to the official FENSA CPS documentation:

• New conservatories or porches without heating
• Newly prepared openings where structural changes have been made
• Loft conversions or property conversions (e.g. splitting a house into flats)
• New builds or new extensions
• Repairs where the door or window frame is not replaced
• Non-residential commercial properties (retail, industrial, schools, medical centres)
• Grade I Listed Properties
• High-risk buildings over 7 storeys or 18 metres in height with more than one dwelling

Note that FENSA applies to replacements only. If you are fitting a door into a brand-new opening that requires structural work, you will need to apply to your Local Authority Building Control (LABC) regardless of whether your installer holds FENSA approval.

Which Door Types Require FENSA Certification?

The table below shows how FENSA applies to each door category sold at DoorsDirect2U. The key distinction is whether a door is external or internal, and whether it carries glazing that affects the thermal performance of the building envelope.

Door Type	Ext / Int	FENSA Required?	Key Notes
Patio Doors	External	Yes	Heavily glazed sliding or folding external doors. Replacement work is notifiable under Building Regs. Must comply with Part L (energy efficiency) and Part N (glazing safety).
French Doors	External	Yes	Double outward-opening glazed doors. Treated as external doors under FENSA. Replacement in an existing opening requires certification.
Bifold Doors	External	Yes	Accordion-style glazed panels opening onto a garden or terrace. Classified as external doors. FENSA certification applies for replacements in existing residential dwellings.
External Doors (front & back)	External	Conditional	Glazed or part-glazed external doors: FENSA applies. Solid doors with less than 50% glazing: registration with FENSA is not mandatory but remains best practice. Compliance with Building Regs still required either way.
Internal Doors	Internal	No	FENSA does not cover internal doors. They do not affect the external building envelope or energy efficiency in the way FENSA regulates. No FENSA certificate is required or available for internal door replacements.
Internal Fire Doors	Internal	No (separate regs)	Internal fire doors fall under Building Regulations Part B (Fire Safety), not FENSA. They must meet FD30 or FD60 ratings and be correctly installed. A FENSA certificate does not apply, but correct installation is still a legal requirement.
External Fire Doors (glazed)	External	Yes	An external fire door with glazing is subject to both FENSA (as an external door) and Building Regs Part B (fire safety). The installer must ensure compliance with both sets of regulations.

Door-by-Door Breakdown

Patio Doors

Patio doors are large-format external glazed units, typically sliding or folding, installed to connect a living space to an outdoor area. Because they form part of the external building envelope, replacing patio doors in an existing residential property is notifiable work under Building Regulations. The installer must certify compliance with Part L (conservation of fuel and power) for energy efficiency and Part N (glazing safety in critical locations).

A FENSA-approved installer handles both the installation and the legal notification to your local council. If your installer is not FENSA-registered, you are responsible for engaging Local Authority Building Control before work starts. Failure to notify LABC means the installation is technically unregistered, which can cause problems when you come to sell the property.

French Doors

French doors are double-leaf outward-opening doors with large glazed panels, typically installed at the rear of a property. FENSA treats them as external doors: replacing them in an existing opening of an existing dwelling requires certification. A FENSA certificate confirms the installation meets current thermal performance standards and has been registered with the local council.

French doors installed in a new extension or conservatory fall outside FENSA scope. That work requires a Building Regulation application through LABC.

Bifold Doors

Bifold doors are multi-panel systems that fold and stack to one or both sides of an opening, creating a wide connection between indoor and outdoor spaces. FENSA classifies them as external doors for certification purposes. Installing bifold doors as a replacement for an existing external opening in a residential property requires FENSA certification or LABC notification.

Bifold doors are increasingly popular for kitchen extensions and garden rooms. If the opening is created as part of a new extension, it falls under the extension building regulations rather than FENSA scope.

External Doors (Front and Back Doors)

Standard front doors and back doors are classified as external doors under FENSA. 

For part-glazed or fully glazed external doors, FENSA certification applies when replacing them in an existing residential property. The glazing must meet the safety and energy standards set out in the relevant approved documents.

For solid doors with less than 50% glazing, the official FENSA CPS documentation states that registration is not mandatory, though it can still be done voluntarily. This is the only door type category where FENSA registration is optional rather than required. Regardless of whether you register with FENSA, the installation must still comply with Building Regulations. Using a FENSA-approved installer for any external door replacement remains the simplest way to ensure compliance is handled correctly.

Internal Doors

Internal doors do not fall within FENSA scope at all. FENSA covers the external building envelope: elements that affect energy efficiency, weather resistance and structural integrity. Internal door replacements do not involve these factors in the same way.

No FENSA certificate exists for internal door installations, and none is required. You can replace internal doors without using a FENSA-registered contractor, and no notification to your local council is needed.

Fire Doors

Fire doors require careful handling because two separate regulatory frameworks apply depending on their location.

• Internal fire doors fall under Building Regulations Part B (Fire Safety). They must achieve the correct fire resistance rating: FD30 for 30-minute protection or FD60 for 60-minute protection. They must be correctly fitted with appropriate intumescent seals, self-closing mechanisms, and compliant hardware. FENSA does not apply to internal fire doors, but correct installation is still a legal requirement under Part B.
• External fire doors that include glazing are subject to both FENSA (as an external door) and Building Regulations Part B. The installer must ensure the door meets fire safety standards and that the installation is certified for energy efficiency and registered with the local council.

The 50% Glazing Rule: Why Solid Doors Are Treated Differently

FENSA draws a specific distinction for external doors based on glazed areas. The official FENSA Competent Person Scheme documentation states: “Doors with less than 50% glazed area can also be registered with FENSA, although this is not mandatory.”

This means that a solid timber or composite front door, or a steel back door with a small glazed panel, does not require FENSA registration, even though it is an external door. The reasoning is that the thermal performance contribution of such a door is less significant than a largely glazed unit.

Even so, the installation still needs to comply with Building Regulations in general, and using a FENSA-approved installer is still the most straightforward way to ensure compliance is correctly handled and documented. The certificate provides proof of compliance that solicitors, mortgage lenders and buyers will look for when the property is sold.

Who Is Responsible for FENSA Compliance?

The legal responsibility for ensuring window and door installations are registered with the local council rests with the homeowner. This is confirmed by FENSA directly: “It’s your responsibility to make sure installations are registered with the local council.” A FENSA-approved installer removes this burden by handling the notification automatically, but the ultimate accountability remains with the property owner.

Homeowners

When you replace an external glazed door in your home, you must either: (a) use a FENSA-approved installer who will certify and register the work on your behalf, or (b) apply to your Local Authority Building Control yourself, pay for an inspection, and obtain a Building Regulations completion certificate independently.

If you proceed without either route, the installation is unregistered. This creates legal exposure, particularly at the point of sale. Conveyancers routinely request evidence of compliance for replacement windows and doors, and an unregistered installation can delay or derail a transaction.

Landlords

Landlords have the same obligations as homeowners for properties they rent. Any replacement external glazed doors in a rental property must be compliant and properly registered. Because rental properties are regularly let, sold, and remortgaged, maintaining clear records of FENSA certificates is both a legal and a practical necessity.

Note that FENSA covers only habitable, heated areas of a domestic building. Doors installed in unheated outbuildings, garages or commercial units attached to a residential property fall outside FENSA scope.

Contractors and Tradespeople

Contractors installing replacement doors on behalf of homeowners or landlords should either hold FENSA approval or advise their clients to obtain LABC sign-off. 

The FENSA Competent Person Scheme states that installers operating under FENSA “have a duty to comply with all aspects of the Building Regulations, not just the core elements of the work they are undertaking.” FENSA carries out random inspections of completed installations via RISA (Rushworth Inspection Services and Auditing Limited) to verify ongoing compliance.

For contractors who complete enough jobs to justify membership, FENSA fees start at a one-off joining fee of £279.88 (ex VAT), with annual fees of £178.85 plus assessment costs and £2.05 per job notification. A contractor completing 40 installations per year pays less than £506 ex VAT annually for full FENSA membership and certification.

What Does a FENSA Certificate Actually Confirm?

A FENSA certificate is not a guarantee of the quality of materials or workmanship. It is proof of four specific things:

• The installation complies with Building Regulations
• The installation meets current energy efficiency standards
• The installation has been registered with the Local Council
• The installer’s guarantee is backed by insurance

The insurance-backed guarantee (IBG) is particularly important. Since 2014, FENSA-approved installers are required to provide IBG policies. If an installer ceases to trade within the lifetime of the warranty, the IBG ensures the policy remains in force. Installations completed before 2014 may not carry an IBG.

If you need a copy of a FENSA certificate for a previous installation, you can request one via the FENSA certificate search tool at forms.fensa.org.uk/fensa-certificate.

Why an Indemnity Policy Is Not a Substitute for a FENSA Certificate

When a property is sold without proper door or window certification, solicitors sometimes suggest an indemnity policy as a workaround. FENSA warns against treating this as a solution.

Sam Davies, FENSA Technical Manager, is direct on the issue: “An indemnity policy gives a false sense of reassurance. It doesn’t check the installation, it doesn’t verify compliance, and it doesn’t protect the homeowner. The real risk remains, buried in the fabric of the property.”

An indemnity policy covers financial exposure if a local authority takes action against an unregistered installation. It does not verify that the installation is safe, energy efficient, or structurally sound. It does not fund remedial work. It simply papers over the absence of proper certification.

FENSA’s position is clear: replacing windows or doors is notifiable work under Building Regulations. Without notification through a FENSA certificate or an LABC application, the work is technically unregistered, and by extension, unregulated.

How to Find a FENSA Approved Installer

FENSA maintains a free installer search tool on its website. You can search by postcode, company name or registration number to find verified FENSA-approved installers in your area. Visit www.fensa.org.uk and use the ‘Find a FENSA Approved Installer’ tool.

Before appointing an installer, FENSA advises homeowners to:

• Ask family and friends who have used door or window installers whether they received a FENSA certificate
• Check the installer’s references by speaking to previous customers directly
• Obtain at least 3 quotes and ensure you are comparing like-for-like specifications
• Get the FENSA certificate commitment, warranties, and completion date in writing as part of a formal contract
• Confirm the installer’s guarantee is covered by insurance before signing

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