Fire Doors in London Homes: When You Need Them and What the Rules Say

A fire door is a door assembly — door leaf, frame, ironmongery, seals, and glazing (if any) — that has been tested and certified to resist fire and smoke for a specified period. Unlike a standard internal door, a fire door is designed to slow the spread of fire and smoke through a building, giving occupants more time to escape.

Fire doors are rated by the duration of protection they provide in a standard fire test:

• FD30: 30 minutes of fire resistance. The standard for most residential applications.
• FD60: 60 minutes of fire resistance. Required in some higher-risk or higher-occupancy situations.

The rating refers to the complete assembly — door leaf, frame, hinges, seals, and closer — all must be certified components. You cannot create a fire door by fitting intumescent strips to a standard door; the whole assembly must be tested and specified together.

Loft conversions

This is the most common residential context where fire doors become mandatory. When a loft conversion creates a new habitable room above an existing dwelling, Building Regulations (Approved Document B) require measures to provide a protected escape route from the new level to the outside.

The standard approach for a house with three or more storeys after the conversion:

• Fire doors (FD30S — the S suffix means they also include a smoke seal) on all doors opening onto the staircase enclosure on all floors
• Mains-wired, interlinked smoke detectors on each floor level

For a two-storey house being converted to three storeys (adding a loft room), the fire protection requirement typically means FD30S doors on any room that opens directly onto the staircase — typically the bedroom and bathroom doors on the first floor, and the door to the new loft room.

The specific requirements depend on the configuration of the house and the staircase. Your Building Control officer will confirm what is needed for your specific property at the time of plan checking.

HMOs (Houses in Multiple Occupation)

Fire safety in HMOs is regulated more strictly than in single-household dwellings, and fire doors are central to that. The requirements depend on the HMO type and the local authority's specific guidance, but broadly:

Large HMOs (mandatory licence, 5+ persons): Typically require FD30S self-closing fire doors to each bedroom, bathroom, and kitchen. Doors from rooms to escape routes (corridors and staircases) must be fire-rated and fitted with door closers.

Smaller HMOs (additional licensing, 3–4 persons): Requirements are set by the licensing authority. Many London boroughs require fire doors throughout, even in smaller HMOs, because the shared escape route logic applies regardless of occupant number.

If you are converting a property to HMO use or applying for an HMO licence, a Fire Risk Assessment (FRA) should be carried out by a competent person. The FRA will identify the specific fire door requirements for your property.

Extensions and new builds

In new extensions and new build homes, Building Regulations require automatic fire door protection in specific locations:

• A door between an integral garage and the dwelling must be FD30S
• In houses of more than two storeys, the staircase must be enclosed and fire doors are required on habitable rooms opening onto it at each floor
• Doors between a boiler room (containing a heat-generating appliance) and the rest of the property may need to be fire-rated in some configurations

For single-storey extensions and for most two-storey residential work, fire doors are not typically required other than in the specific circumstances above.

Purpose-built flats and converted flats

For converted houses containing flats, fire doors are required:

• Between each flat and the common parts (entrance hall, staircase, corridors) — FD30S
• Between the common parts and any storage areas, boiler rooms, or risers

For purpose-built flats, the fire strategy for the building determines the requirements for the individual flat entrance doors and any internal compartmentation. This is typically specified as part of the building's original Building Regulations package and any alterations should not compromise it.

FD30: 30-minute fire resistance — the door resists the passage of flames for 30 minutes in a standard fire test.

S (smoke seal): The door also incorporates seals (typically intumescent brush seals or strip seals) that expand or compress when heated, and cold smoke seals that restrict smoke movement even before the fire reaches the door.

In residential properties, the S specification is almost always required alongside the FD30 rating, because smoke inhalation is responsible for the majority of fire deaths — not flames. FD30S gives a more complete level of protection than FD30 alone.

A compliant fire door assembly requires:

1. Certified door leaf: Typically 44mm solid core construction with a fire-rated core. Must be tested and certified as part of an assembly. Check for the certification label on the door edge.

2. Certified frame: The frame must be compatible with the door leaf. Many fire door failures in practice are caused by fitting a certified door into a non-compatible frame.

3. Intumescent seals and smoke seals: Typically fitted in a rebate around the door leaf or frame. Intumescent material expands when heated, sealing the gap and preventing flame passage. Cold smoke seals (typically brush seals) seal the gap at ambient temperatures.

4. Certified hinges: Typically three hinges minimum (the standard is often BS EN 1935 Grade 13 or equivalent). Cheap hinges can cause the door to sag or fail the test gap requirements.

5. Self-closing mechanism: Fire doors must be self-closing — a compliant door closer (EN 1154 CE marked) is required. The door must close fully into the frame from any open position without being manually pushed.

6. Hold-open devices (if used): If a fire door must be held open for practical reasons (eg. a kitchen door held open during normal use), only compliant electromagnetic or acoustic hold-open devices connected to the fire alarm system may be used. These release the door automatically when the alarm activates. Wedging a fire door open is prohibited.

7. Glazing (if fitted): Any glazing in a fire door must be fire-rated glass — ordinary glass will fail quickly in a fire. Wired glass, fire-resistant toughened glass, or intumescent glass are options depending on the performance required.

Fitting self-closing strips to a standard door: This does not make a fire door. The door leaf, frame, and ironmongery must all be tested and certified together.

Wedging fire doors open: This immediately removes all fire protection provided by the door. The door must always be free to close fully, or a compliant hold-open device must be used.

Missing or damaged seals: Over time, intumescent and smoke seals can become compressed, damaged, or missing. Inspect fire doors regularly and replace seals immediately if damaged.

Incorrect frame or hinges: A certified door leaf is only as good as the frame it sits in. Non-certified frames and undersized hinges are common causes of non-compliant installation.

Gaps too wide: The gap between the door leaf and the frame should be 2–4mm on all sides. Larger gaps indicate that the door or frame has moved and the seal performance is compromised.

For most single-family homes, a formal FRA is not a legal requirement, but the fire strategy is assessed by Building Control as part of the Building Regulations application for any relevant work (loft conversions, HMO conversions, etc.).

For HMOs, an FRA is a legal requirement under the Regulatory Reform (Fire Safety) Order 2005 — the landlord or managing agent is the responsible person and must ensure a suitable FRA is in place and reviewed regularly.

For common parts of converted flats, an FRA is also a legal requirement.

Fire doors are a mandatory and safety-critical element of loft conversions, HMO licensing, and several other residential construction contexts in London. They must be complete, certified assemblies — door leaf, frame, seals, hinges, and closer — all specified together. The self-closing mechanism must work correctly, the door must close fully from any position, and the seals must be intact. If you are doing a loft conversion, HMO conversion, or any work where Building Regulations require fire protection, ensure your contractor specifies compliant fire door assemblies from a reputable manufacturer and that Building Control confirms acceptance as part of the sign-off process.