Out of all the measures in place to protect a building from fire, fire doors are among the most visible and frequently used. However, many people do not know the full extent of their role within a fire protection strategy.
As well as providing a safe evacuation route, fire doors help prevent a fire from spreading throughout a building through compartmentation. Compartmentation is a process where buildings are divided into manageable ‘compartments’ and reinforced by either fire-resistant materials or structural measures such as fire doors or cavity barriers. Intumescent strips are added to fire doors to ensure they provide fully-compliant compartmentation.
Intumescent paint expands when exposed to extreme heat. This means that in the event of a fire, intumescent strips will close any gaps between a fire door and the frame so that flames and smoke cannot pass into other rooms. Depending on the type of intumescent strip, you can expect to get 30 to 60 minutes of fire resistance with this installation. However, intumescent strips can be rendered ineffective if fire doors are neglected or misused – a common occurrence in buildings with multiple occupants. For example, in 2019 it was estimated that 64% of premises visited by fire services had fire doors wedged open.
CLM Fireproofing will ensure your fire doors are fully compliant
with industry regulations, helping you to protect your building and its occupants.
This article will first provide an overview of industry best practice surrounding intumescent strips, helping building owners and health and safety professionals understand their importance within a passive fire protection system. It will also include some basic installation guidelines, so those responsible for fire safety maintenance can be confident in their compliance with fire door regulations.
Intumescent strips are fitted to fire doors, and when exposed to extreme heat they expand to close any gaps or edges that might facilitate the spread of smoke and fire.
Intumescent strips for fire doors are generally designed to provide around 30 – 60 minutes of fire resistance. This means they contain the spread of fire for a specific period so that occupants have enough time to safely evacuate a building.
All fire doors are rated based on their fire resistance features. This is known as an FD rating and is measured based on several different criteria. FD 30 and FD 60 are the main categories of fire doors. FD 30 means a fire door has a minimum of 30 minutes of fire resistance. A door with a rating of FD60S offers a minimum of 60 minutes of fire resistance and is a smoke sealed door. It is generally accepted that to provide the required level of fire resistance, all fire doors should be reinforced with either intumescent strips, cold smoke seals or a combination of both.
According to the British Standard 476 fire safety standards, most doors need to be S-type (smoke sealed) doors. Having a fireproof door installed with intumescent strips can help the door qualify for these standards. Seals need to limit leakage to a rate of 3 cubic metres of smoke through 1 metre of door edge per hour. If you require additional clarification on fire door requirements, we advise you to contact the manufacturer of your fire door’s make and model.
The main point of reference for compliant fire door installations is their fire rating, which would be provided by the manufacturer in the form of testing data. These ratings depict the amount of time that a door can withstand fire damage. For example, a fire door with the rating of FD30 means it has a fire resistance rating of 30 minutes (these can range between FD30 to FD240). To learn more, consult our guide to fire door regulations.
A building’s regulations will also stipulate where its fire doors are, as well as where intumescent strips need to be installed. In a standard fire door the door leaf has to be able to move within the frame, and for this to be possible there has to be a small gap around the perimeter. Furthermore, regulations specify that this gap between a fire door and a frame should be between 2-4mm to accommodate an intumescent strip or smoke seal.
As of January 2023, responsible persons in a multi-occupancy residential building are legally obliged to carry out quarterly checks on fire doors in common areas. According to government guidance, a responsible person must consider ‘if there are any gaps around the door frame and that seals and hinges are fitted correctly’. Later in this article, we will provide more insight into inspecting and maintaining intumescent strips.
Fire door seals are fitted to the stiles and head of a door set, either in the grooves of the doorframe or mounted on the surface. They are designed to swell once the ambient temperature exceeds 200°C, which will usually occur within the first 10-20 minutes of a fire. Properly installed intumescent strips will fill gaps between the door and frame to achieve fire compartmentation.
Regulations surrounding intumescent strips also require specific installation and fitting based on your building and fire door type. For example, some doors require a cold smoke seal to protect people and property from smoke damage.
Intumescent strips are fairly easy to install, provided the fire door in question has the right grooves in place. Otherwise, you will need to create grooves using a router that matches the width of the intumescent strip.
Once you have your groove in place, you can measure and cut your strip to ensure it’s the right width for the door. You should then check to see that the groove is clean and free of any dust or debris,otherwise, the strip’s self-adhesive back may not stick into the groove properly. Upon fitting the strip, you should test to see if the door still closes properly. You may need to use a door closer so it shuts properly. If so, fire safety regulations stipulate that it must be a Grade 3 door closer or above.
Painting over an intumescent strip could violate its integrity and render a fire door non-compliant. As painting an intumescent strip is unlikely to serve any purpose outside of aesthetics, we advise against this course of action and suggest that any strips that have been painted be replaced.
Like all other fireproofing materials, intumescent strips should never be “set it and forget it.” Intumescent strips can crack, warp, or partially detach from a door with age. They can also sustain damage from door use or building repairs. Therefore, they should be inspected every three months (as of January 2023), or following any alterations as part of a wider refurbishment project. This inspection must include checking the proper placement and efficacy of intumescent strips and seals. Any damaged or missing strips should ideally be replaced with a new one of the same size, type and brand as the original.
It’s important to carry out this inspection alongside other fire door maintenance tasks, such as checking hinges, locks, and other door elements. The door frame must be free of damage or gaps and it must close soundly. It must also have a minimum of three hinges that are in good working order. This helps ensure the fire strips maintain the same level of effectiveness as the original installation.
CLM Fireproofing are the UK’s leading experts in passive fire protection, with over 35 years of experience in the industry. Our FIRAS-accredited specialists offer fully compliant fire door inspection, installation and maintenance services (including intumescent strip fitting). Contact the CLM Fireproofing team today to find out more.