Fire doors – Common queries from our fire safety forum

Safelincs operates a fire safety forum where people’s fire safety questions are answered by professionals. One of the frequently-raised topics are Fire Doors. This blog compiles some of the key points raised by the forum.

A fire door is designed to function both as a door and as a barrier to a fully developed fire in a building

Whilst any closed door will help to delay the spread of a fire, those designated specifically as fire doors must be capable of resisting the effect of fire for a period set out in its specification – typically 30 minutes.

Strictly speaking a fire door should be referred to as ‘a fire resisting doorset’ or fire door assembly including a frame as well.

This is because the door and the door frame act together in the context of fire resistance. In information pertaining to fire resistance you will see the actual door referred to as the ‘door leaf’ or simply the ‘leaf’. Other components are hardware (closers, hinges, etc.) and seals which must be to fire rated standards.

There are two types of smoke seal

  • A brush type seal will prevent the escape of cold smoke around the edges of the fire door. Smoke inhalation can be more dangerous than the fire itself. It is important, when fitting smoke seals, that they do not hinder the full and effective closure of the door.
  • Intumescent fire door seals remain dormant under normal conditions but expand greatly in the heat of a fire to close the gap between the door and its frame. A fire door required to provide resistance to the passage of a well-developed fire must be fitted with intumescent seals. These seals activate at temperatures that are above human survival levels, so there is no danger of them expanding and trapping people trying to escape.

Safelincs’ fire door seals contain both an intumescent strip as well as a brush to stop both smoke and fire. There are rare occasions where a brush is not helpful (if traces of smoke are required to drift through the door gap to trigger an alarm on the other side of the fire door). In these very rare cases, please contact our staff and we will supply you with intumescent strips without brush.

Fire doors are rated in accordance with the length of time they will resist a fire

A door rated FD30 will resist the passage of fire for 30 minutes, an FD60 for 60 minutes and so forth. If a fire door is rated FD30s it will have been fitted with the appropriate seal containing both intumescent and brush to resist the passage of cold smoke for 30 minutes as well.
Safelincs sells rebated or surface-mounted intumescent fire door seals which resist fire for 30 or 60 minutes (suitable for FD30 or FD60 fire doors). All Safelincs seals are available for single and double fire doors and can be fitted in the frame or the door leaf.

British Standards set out details on the permitted gaps around a fire door

BS 8214:2008 states that the gap along the sides, top and between the leaves of a double door should be 3 mm +/- 1 mm. Under-door (threshold) gaps should be in accordance with the manufacturer’s installation instructions for the particular doorset design.
If the fire door is required to stop cold smoke as well (FDs) it should be fitted with a threshold seal underneath the door to stop the smoke. When fitted, threshold smoke seals should give an even contact with the floor but should not significantly increase friction that could hinder the opening or closing of the door.

When fitting a fire door, the door leaf can be shortened by cutting a section off at the bottom. However, the amount that can be removed at the sides is strictly limited. You need to contact the manufacturer about the maximum that can be planed off.

Fire doors should not be left open

Fire door closers have to be used to ensure that fire doors are kept shut, except when people are passing through them. There are a number of different types of closers on the market, including some which are concealed and unobtrusive – maintaining the character of a door – ideal for stylish offices or historic buildings.

It is illegal to prop fire doors open unless the door holder (also called fire door retainer) is capable of automatically releasing the door in case of a fire being detected. These work either acoustically (‘hearing’ the fire alarm) or by being wired into a building’s fire alarm system.

If users (for example, disabled people) find fire doors with closers difficult to open, ‘swing free’ devices can be used

In some circumstance the force needed to open a fire door against the resistance of the fire door closers is too great for the user to manage. Bedroom doors in care facilities for the elderly or disabled and some rooms in clinics or hospitals are examples. Such doors can be fitted with “swing free” devices. These allow the door to be easily opened or closed without any door closer resitance. They also stay open in any open position required. They are linked to a fire alarm system and will resume their self-closing function in the event of a fire.

The entrance doors to flats, within a block of flats, should be fire doors

Where there a re jointly used exit routes the individual entrance doors in blocks of flats should usually be fire doors to safeguard residents in the building.

Fire doors can be painted with ordinary paint; however, fire door fittings need to be fire-rated

Door fittings include hinges, door closers and glazing. Locks just need to be CE marked (the CE marking indicating compliance with EU product legislation). Fire doors seals can be painted over although excessive thickness of paint should be avoided.

Fire doors can be fitted with glass panels

If glazing is required, this has to be carried out using fire resistant glass. There are two main types: Georgian wired and clear glass. Safelincs offers different glass types and a range of common fire door glazing dimensions. Its manufacturing plant will fit the fire door windows and certify the fire door and glazing with a BWF (British Woodworking Federation) certificate.

Fire doors can be fitted with a security viewer

Security viewers can be fitted to fire doors and offer 60 minutes of fire protection. Safelincs offer two models that will cover doors between 35mm and 62mm thick.

Fire doors should be professionally installed

Although a competent builder or joiner can install a fire door, the recommendation would be that the work is carried out under the auspices of the Accredited Fire Door Installers Scheme. This scheme has been developed by the British Woodworking Federation (BWF) in association with FIRAS (installer certification scheme), with the purpose of ensuring that fire door installations are carried out correctly, safely and in compliance with current Building Regulations.

Once the fire door has been installed, it is also important that you carry out regular maintenance checks to ensure that it remains fit for purpose. Ask the installer for guidance on the issues to look for. If you choose to keep the door open with a fire door retainer, close the door at night to avoid the door warping.

Fire doors should not be confused with fire exits

Fire exits are there to ensure a safe escape for people in the event of a fire. That is they have to open easily from the inside and need to open fully. Final fire exits leading to the outside of a building do usually not have to be fire resistant. An exception are fire exits leading to major external evacuation routes. However, fire doors are also fire exits if they are on the route to the final fire exit, eg in corridors.

Difference Between Fire Doors and Fire Exits

The issue of fire doors and fire exits can be confusing for non-professionals in fire safety. If you have to replace some of the doors in your premises with fire doors or you have to improve egress from a building with panic bars on fire exits, it will be helpful to have a clear understanding of the differences between fire doors and fire exits.

A fire door is an internal door, whose purpose is to i) create/protect an escape route through a building in a fire situation; and ii) compartmentalise a fire, to stop flames and smoke spreading from one section of the building to another. Examples of locations of fire doors include stairwells, where they protect the stairs from corridors opening on to them; kitchens/catering facilities, storage areas that house combustible materials such as paper and card, and boiler rooms.

Fire doors have to be kept close at all times unless certified fire door retainers are installed (not just a door wedge!) which hold the fire door open until a fire alarm is set off.

Certified fire doors of solid timber construction are designed to resist the smoke and flames of a fire for a minimum specified length of time, typically 30 minutes (FD30), when closed. Because a fire door is not simply a block of wood in a frame but an assembly of fire resistant parts – door leaf/leaves, door frame, hardware (e.g. locks, latches, hinges, etc), any glazing, smoke/intumescent seals and an automatic closing device – it is also known as a fire doorset.

A fire exit door on the other hand, is an external door; it can be left open and does not have to be fire resistant. The purpose of the fire exit door is to allow a quick and un-hindered escape through a well lit door into a place of safety while stopping un-authorised access from the outside. Fire exits doors should open easily and, wherever possible, in the direction of traffic flow. If it is a security door that is usually kept locked but will be used by members of the public in an emergency situation, it will have to be fitted with a panic or push bar. By enabling the swift passage of people to a place of safety, the final exit door will have performed its function; it does not have to be a fire door to accomplish this. Fire exit doors can also be opened from the outside, if for example a panic bar with a key lock override is fitted. Fire exits must never be obstructed and have to be clearly marked and well lit. Best practice dictates that fire exit signs are fitted above fire exits.

Why are Fire Door Closers Important?

In order for fire doors to function properly, they should remain closed when the door is not in use. As obvious as this sounds, in a busy office building it can be difficult to ensure that fire doors are being closed. Therefore automatic fire door closers are installed to ensure that, after a door is opened, it naturally returns to a closed position where it can offer the maximum fire safety.

Fire door closers are a legal requirement in most settings

How do fire doors closers work?

Door closers work by using the energy built-up when opening the door, to close it. Fire door closers have different closing strengths depending on the weight of the fire door. The closing strength is otherwise known as the EN power size. Smaller and lighter fire doors do not need as much strength in the fire door closer to shut the door. Many door closer models have an adjustable power size. The configuration of the door closers will also depend on the design of the door (inward/outward closing).

How do I check my door closer is working?

This fire door maintenance checker is a useful guide for checking all parts of your fire door to make sure they are compliant and operational. An unlatched or non-operational door closer will not shut the fire door if a fire breaks out. This could have disastrous consequences.

Which fire door closer do I need?

There are a number of different types of fire door closer available including closers that are even concealed within the doors themselves. Free-swing closers enable the doors to be held safely in an open position or to swing freely on the hinges. This can help to improve accessibility, particularly for anyone with mobility difficulties or in busy areas. In the case of a fire, the fire alarm will trigger these hold-open devices and allow the door closer to close the door.

If you are not sure which fire door closer you need, compare features and prices in this overview of fire door closers. Alternatively, contact our customer support team on 0800 612 6537.

Retrofitting or Replacing Fire Door Seals

Following a fire risk assessment, doors are sometimes re-designated as fire doors if the door and frame are substantial enough to be justifiably counted as a nominal fire door. The same applies to older fire doors which do not follow the latest specifications. In these cases, fire door seals are retrofitted, and to avoid having to cut a rebate in either the door or the frame, surface mounted fire door seals can be fitted. These are stuck to the frame or door with their self-adhesive backing and sometimes nailed as well to give them increased longevity.

Where a fire door rebate already exists, or the existing rebated fire door seal has been damaged, rebated intumescent fire door seals can be fitted.

We offer a range of fire door seals: fire only, or combined fire and smoke. Both variants contain intumescent material that swells if a fire breaks out to seal the gap around the fire door. Seals that cover smoke also contain a brush-type smoke seal to stop smoke travelling through the gap before the intumescent material expands. There are some applications where a gap should not have smoke seals: e.g. if the fire door has been installed on the exit of a room which has no smoke detectors on its own. In this case, the fire alarm system can only be triggered if smoke can leak out around the fire door and set off the fire alarm system in the circulation spaces, but these cases are quite rare.

Fire door seals are fitted on three sides of a fire door with the gap underneath the door not being covered, though there are products available to prevent smoke from escaping under doors if necessary.

If new fire door seals are fitted for the first time, make sure that fire door hinges, fire door closers and, where necessary, intumescent door lock protection are fitted as well.