Fire Door Letter Plates: When Are They Allowed in the UK?

A letter plate can look like a small fitting, but on a fire door it creates a real break in the door leaf. That is why fire door letter plates aren’t automatically allowed simply because they are described as fire-rated.

In the UK, the safest approach is to avoid cutting a letter plate into a fire-resisting door where a separate mailbox or wall-mounted post box can work. Where a letter plate is necessary, the complete door assembly, letter plate, intumescent materials, and installation method must be suitable for one another. The key rules become clearer when you separate fire performance from security compliance.

Key Takeaways

• Fire door letter plates should be avoided wherever a separate postal solution is practical.
• A permitted letter plate must have evidence from a relevant fire test, such as BS 476-22 or BS EN 1634-1.
• The door must have been tested to accept that type of letter plate and have similar construction.
• Intumescent liners and seals must match the tested system and follow the manufacturer’s fitting instructions.
• TS008 and PAS 24 relate mainly to security, so they don’t prove that a letter plate provides fire protection.

When are fire door letter plates allowed?

UK guidance doesn’t impose a simple ban on every letter plate fitted to a fire-resisting door. However, it treats the alteration as a risk to the door’s tested performance. Cutting an opening can affect integrity, insulation, smoke control, and the way heat moves through the leaf.

The Door and Hardware Federation’s Fire Code guidance for fire and escape doors says letter plates fitted to fire doors should have been included in satisfactory testing. The recognised test routes include BS 476-22, BS EN 1634-1, and BS EN 1634-2.

That evidence must relate to more than the letter plate on its own. A product tested in a timber door may not be suitable for a steel doorset, a composite door, or a different thickness of timber leaf. The door construction, frame, seals, hardware, and letter plate need to match the tested arrangement closely.

This is the point many property owners miss. A label saying “30-minute fire-rated letter plate” doesn’t automatically make every door safe. The product may have achieved a particular result in a controlled test, but that result only applies within the conditions of that test.

A fire-tested letter plate is only useful when the door has also been tested to accept it.

Where possible, a wall-mounted mailbox, communal post box, or free-standing postal box is a better solution. It avoids cutting the fire door and keeps the original leaf intact. This option is especially sensible where the door protects a shared escape route or separates flats from a communal corridor.

If a letter plate must be installed, ask for written evidence showing the product’s fire performance, the door types covered, the required intumescent components, and the permitted installation details. A general product description isn’t enough.

What standards apply to fire door letter plates?

Several standards can appear in product information, but they don’t all cover the same issue.

BS EN 1634-1 covers fire resistance testing for door, shutter, and similar building-element assemblies. It assesses how the complete assembly performs when exposed to fire. You can read a useful BS EN 1634-1 testing guide for an explanation of how these tests measure resistance over time.

BS 476-22 is another fire-resistance test standard referenced in UK fire-door hardware guidance. A test report under either route needs careful reading. Check the exact construction, fire rating, size, glazing, hardware, and letter plate arrangement rather than relying on a product name.

BS EN 13724 relates to letter plate dimensions and postal delivery requirements. It may help show that a letter plate is suitable for normal postal use, but it doesn’t prove that the fitting is fire-resistant.

Security standards are separate again. TS008 covers security performance for letter plates, including resistance to manipulation, fishing, and certain forms of attack. PAS 24 covers security for complete doorsets and windows in relevant applications. A letter plate can meet TS008 and still lack suitable fire-test evidence.

For new homes, Approved Document Q is relevant to security standards for doors providing access to a dwelling. A TS008-compliant letter plate may support the security requirements, but that doesn’t remove the need to protect the fire performance of a fire-resisting doorset.

The product should also come with the intumescent material used during testing. Intumescent components expand when heated and help close gaps around the opening. Replacing that material with a different seal, omitting it, or fitting it in the wrong position can invalidate the tested arrangement.

Fire doors in flats and communal buildings

Flat entrance doors need particular care because they often protect the route used by other residents to escape. A letter plate that allows smoke or flames into a communal corridor can affect more than one household.

The UK government’s guidance on the Fire Safety (England) Regulations 2022 specifically warns that a newly fitted letterbox must be suitable for use in a fire-resisting door and installed by a specialist contractor.

In buildings where the top storey is more than 11 metres above ground level, the Responsible Person must arrange checks of flat entrance doors at least every 12 months. Fire doors in communal areas require checks at least every three months. These inspections can identify damaged seals, missing closers, excessive gaps, or a letter plate that no longer closes properly.

A letter plate should close firmly after each delivery. Residents shouldn’t wedge it open, tape it back, or leave post trapped inside the flap. The government guidance also refers to an industry-standard gap of no more than 4 mm around the sides and top of a fire door. The bottom gap should be as small as practical while allowing the door to open without snagging.

A fire door inspection should consider the whole doorset, including:

• The door leaf, frame, hinges, closer, and latch
• Intumescent and smoke seals around the edges
• The letter plate, flap, fixing method, and surrounding material
• Damage, distortion, gaps, or unauthorised alterations
• Whether the door closes fully without sticking

If a flat entrance door has an old, loose, or damaged letter plate, don’t replace it with a standard domestic model. Ask a competent fire-door professional to identify a compatible system first.

How to check a letter plate before installation

Before approving fire door letter plates, collect the information needed to compare the product with the existing doorset. The first step is to identify the door’s rating and construction. Look for the manufacturer’s label, certification plug, or inspection records. An FD30 timber door, a steel personnel door, and a glazed communal door won’t necessarily accept the same hardware.

Next, request the letter plate’s test evidence. The documentation should state the standard used, the door construction tested, the fire rating achieved, and the installation conditions. It should also identify the intumescent kit supplied with the product.

The installer should then confirm that the proposed position and size match the tested arrangement. Lower-door positioning is often preferred for postal access, but the exact location still needs to follow the product’s instructions. Enlarging the cut-out or moving the plate can change the way the leaf performs.

Avoid these common mistakes:

• Fitting a standard letter plate because it has a metal flap
• Treating a TS008 rating as proof of fire resistance
• Reusing old intumescent material
• Cutting a larger opening than the test permits
• Installing the plate without recording the product details
• Drilling through seals, glazing, or structural parts of the doorset

For a commercial property, the decision should form part of the site’s fire-risk assessment and maintenance records. If the door protects an escape route, a competent person should review the proposal before work starts.

A free site survey can help identify whether a tested letter plate is appropriate or whether a separate postal box would be safer. UK Doors & Shutters works with fire doors, steel doors, shutters, and related access systems across Bolton, the North West, and wider areas. You can book a free installation survey to discuss the existing door and the available options.

What should you do if a letter plate is already fitted?

Don’t remove or replace an existing letter plate without checking the door’s certification and condition. An old installation may have been acceptable when fitted, or it may have no reliable evidence at all. The surrounding timber or steel can also suffer damage over time.

Check that the flap closes, the fixings remain tight, and the intumescent material hasn’t fallen out or become damaged. Look for heat damage, splits, loose screws, oversized gaps, and signs that someone has altered the door.

If the door is in a block of flats, report concerns to the managing agent, landlord, or Responsible Person. If it is at a workplace, notify the facilities manager or person responsible for fire safety. A repair that improves security but damages fire performance creates a different safety problem.

Where the evidence can’t be confirmed, a competent contractor may recommend replacing the complete doorset or moving postal access away from the fire door. That decision depends on the door’s rating, location, construction, and the building’s fire strategy.

Conclusion

Fire door letter plates are allowed in the UK only when the specific product and the specific doorset have suitable test evidence and the installation follows the tested method. Fire performance and security performance are separate requirements, so TS008 or PAS 24 alone isn’t enough.

Avoiding a cut-out is usually the clearest option. Where a letter plate is necessary, use a compatible fire-tested system with the correct intumescent components and professional installation. If you need advice about a fire door, steel door, or related security opening, Contact Us for practical support before altering the doorset.