Unlike conventional doors, a fire door is built to be more resistant to fire. It is also usually fitted with seals around the edges that can halt the spread of fire and smoke to unaffected areas of your building. One of the key components in a fire door is the intumescent strip.<\/p>\n
Quick Answer<\/h2>\n
Intumescent strips are fitted to fire doors or frames to expand when exposed to heat, helping to seal gaps and restrict fire spread. They only work properly when they are correctly specified, undamaged, compatible with the doorset and not painted over or removed.<\/p>\n<\/div>\n\n
What is an Intumescent Strip?<\/h2>\n
An intumescent strip is a heat-activated fire seal fitted to a fire door or frame. In high temperatures, it expands to close the gap between the door and frame, helping maintain the door\u2019s fire resistance rating.<\/p>\n
An intumescent strip is a fire-resistant seal fitted around the edges of a fire door or frame that expands when exposed to heat. When a fire occurs, the strip swells to seal the gap between the door leaf and frame, helping to prevent the spread of flames and hot gases for the rated fire resistance period (for example FD30 or FD60).<\/p>\n
The intumescent strip around the door expands and blocks any gaps around the door space on exposure to heat from a fire. With the gaps around the door closed, the spread of a fire can be contained, albeit for a while.<\/p>\n
Intumescent strips and smoke seals should be reviewed as part of routine fire door checks and more detailed fire door inspections<\/a>. Where doors have been installed, replaced or upgraded, the specification should also be considered alongside BS 8214 fire door installation guidance<\/a>.<\/p>\n There are several key reasons why you should ensure that your fire doors have intumescent strips, including:<\/p>\n Note that the primary function of intumescent strips on fire doors is to contain the spread of a fire and not the smoke. To prevent smoke from filtering into other parts of your building in the event of a fire, you also need to add smoke seals around your fire door.<\/p>\n Intumescent seals are typically made of intumescent materials.<\/p>\n An intumescent material is a substance that does not burn immediately on exposure to heat but usually expands in volume while decreases in density.<\/p>\n Intumescent seals can be made from a wide range of synthetic polymers and resin binders such as silicone or epoxy.<\/p>\n Intumescent seals are typically fixed into the door frame, but they can also be fitted into grooves along the door.<\/p>\n To determine the most ideal placement of intumescent seals, it is essential to consider your door design.<\/p>\n As mentioned earlier, intumescent strips will help halt the spread of fire in your property, but they will not hold the raging flames forever. The duration that these strips can hold fire back is usually determined by the thickness of the film used.<\/p>\n The standard intumescent strips available in the market can help contain a fire for either 30 or 60 minutes.<\/p>\n The required size of an intumescent strip is determined by the fire door manufacturer\u2019s test evidence and certification, not just by thickness alone. Typical strip widths include 10mm, 15mm and 20mm, but the correct size must match the door\u2019s fire resistance rating and specification.<\/p>\n On the other hand, if you need the seal to hold out for around 60 minutes, you should use an intumescent film that is at least 20mm thick.<\/p>\n The correct size is not chosen based on guesswork or door thickness. It must match the specific fire test evidence for the door assembly, including the door leaf, frame, hinges and hardware.<\/p>\n Different fire door assemblies require different types of intumescent seals depending on certification, acoustic requirements, and smoke control needs.<\/p>\n There are several types of intumescent strips used in fire doors, including:<\/p>\n The correct type must align with the door\u2019s fire test evidence and manufacturer certification.<\/p>\n A smoke seal is a film that is usually placed between the door and the entire door frame to stop toxic smoke from seeping into other areas of a building that have not yet caught fire. Unlike an intumescent seal that can stop the spread of fire and some smoke, a smoke seal only stops the spread of smoke but does not contain the spread of fire.<\/p>\n The main difference between a smoke seal and an intumescent seal is that once affixed to the door frame. Smoke seals are usually visible, whereas intumescent strips may be visible or concealed depending on installation method.<\/p>\n Note that fire safety experts advise that both smoke seals and intumescent seals are fitted on fire doors for total protection in case of a fire.<\/p>\n When buying a fire door for your building, it is recommended that you check whether it comes fitted with both an intumescent strip and smoke seal. If you buy a fire door with both components with a 30 minutes resistance rating, it should be labelled ‘FD30S’. If you are purchasing a fire door with a 60 minutes resistance rating, it should be labelled ‘FD60S’.<\/p>\n In most cases, intumescent strips should only be replaced by a competent person.<\/p>\n Fire doors are tested and certified as complete assemblies, which includes the door leaf, frame, hinges, glazing, hardware, and seals. The size, type, and position of the intumescent strip form part of that tested specification. Replacing a strip with the wrong size or type can invalidate the door\u2019s fire resistance rating.<\/p>\n Although replacement strips are widely available, it is essential that any replacement matches the original manufacturer\u2019s certification and fire test evidence. Simply choosing a strip based on width or thickness alone may not be sufficient.<\/p>\n If an intumescent strip is damaged, missing, painted over, or altered, it should be assessed as part of a formal fire door inspection. In many buildings \u2014 particularly residential and non-domestic premises \u2014 improper alterations could lead to non-compliance under fire safety legislation.<\/p>\n When in doubt, always seek advice from a competent fire door inspector or fire safety professional to ensure continued compliance and performance.<\/p>\n Under the Regulatory Reform (Fire Safety) Order 2005<\/a>, the Responsible Person must ensure that fire doors are properly maintained and remain effective.<\/p>\n Approved Document B<\/a> of the Building Regulations requires fire-resisting doors to be installed as tested and certified, including correct intumescent seals.<\/p>\n British Standard BS 8214<\/a> provides guidance on the correct installation and maintenance of fire door assemblies, including seals.<\/p>\n Failure to install or maintain intumescent strips correctly may compromise the door\u2019s fire resistance performance.<\/p>\n Intumescent strips are a critical component of any certified fire door assembly. In the event of a fire, they expand under heat to seal the gaps around the door leaf, helping to prevent the spread of flames and hot gases for the door\u2019s rated resistance period.<\/p>\n However, intumescent strips must be correctly specified, installed, and maintained in line with the door manufacturer\u2019s certification and current fire safety standards. Incorrect sizing, damage, or removal can compromise the performance of the entire fire door.<\/p>\n As part of ongoing fire door inspection and maintenance, intumescent strips should be regularly checked to ensure they remain intact, continuous, and free from alteration.<\/p>\n Properly fitted and maintained intumescent seals play a vital role in protecting escape routes, containing compartment<\/a> fires, and supporting overall building fire safety compliance.<\/p>\nWhy Should You Install Intumescent Strips on Your Doors?<\/h2>\n
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<\/p>\nWhat Are the Components Used in Fabricating an Intumescent Strip?<\/h2>\n
Where Should Intumescent Strips Be Fitted?<\/h2>\n
What Size of Intumescent Strips Should You Use on Your Doors?<\/h2>\n
Types of Intumescent Strips<\/h2>\n
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![\"Fire](\"https:\/\/fire-risk-assessment-network.com\/blog\/wp-content\/uploads\/2019\/09\/Fire-Door-Keep-Shut-Sign.jpg\")
<\/p>\nWhat Is the Difference Between Intumescent Strips and Smoke Seals?<\/h2>\n
Can You Replace Intumescent Strips Yourself?<\/h2>\n
Intumescent Strips and UK Fire Safety Law<\/h2>\n
Conclusion<\/h2>\n