Intumescent strip
Contents |
[edit] Introduction
Intumescence is a chemical process which involves the swelling of crystals on heating and is often accompanied by a violent escape of moisture.
In a building, the heat of a fire can make intumescent material expand and bubble, sealing gaps, such as those between a door and its frame or around glazing. This is of great importance for fire safety as it can help reduce the spread of smoke and flame, allowing occupants additional time to escape before the fire spreads or there is a dangerous level of smoke.
Placed around a door opening, a strip of intumescent material can stop the spread of fire and smoke for up to an hour. However, these strips should be inspected regularly for any tears or damage. If damage is evident, the strips should be replaced as soon as possible as their performance in a fire may have been compromised.
Intumescent strips are particularly useful in apartment buildings and offices that have shared stairwells and fire escapes. They are usually fitted into the door frame but are sometimes recessed into groves cut into the door. It is possible to fit normal doors with an intumescent strip but this will not make them fire doors.
[edit] Types of intumescent strip
[edit] Fire only
Fire-only intumescent strips are activated on contact with fire, expanding and bubbling as the temperature rises.
[edit] Fire and smoke
This type of intumescent strip expands and seals in the same way. However, it incorporates a brush strip which stops the spread of smoke even before expansion has occurred through heat activation. This is important as, for example, doors at a distance from the fire may not be subject to the heat at the fire’s origin therefore their intumescent strips will not have yet been activated by heat. However, if fitted with a fire and smoke intumescent seal, cold smoke can be prevented from spreading before the heat and flames have reached the door.
[edit] Selecting the right seal
The correct seal type and size for any particular door can be determined by reference to door-test data. Once cut to the right length, most intumescent seals have a self-adhesive backing to allow a secure fit into the groove.
[edit] Related articles on Designing Buildings
- Cavity barrier.
- Concrete vs. steel.
- Finishes.
- Fire protection engineering.
- Fire resistance.
- Fire safety design.
- Installing fire protection to structural steelwork (GG 85).
- Intumescent coatings in buildings
- Intumescent fire and smoke seal.
- Metal fabrication.
- Paints and coatings.
- Passive and reactive fire protection to structural steel (IP 6 12).
- Substrate.
Featured articles and news
BSRIA Sentinel Clerk of Works Training Case Study
Strengthening expertise to enhance service delivery with integrated cutting-edge industry knowledge.
Impact report from the Supply Chain Sustainability School
Free sustainability skills, training and support delivered to thousands of UK companies to help cut carbon.
The Building Safety Forum at the Installershow 2025
With speakers confirmed for 24 June as part of Building Safety Week.
The UK’s largest air pollution campaign.
Future Homes Standard, now includes solar, but what else?
Will the new standard, due to in the Autumn, go far enough in terms of performance ?
BSRIA Briefing: Cleaner Air, Better tomorrow
A look back at issues relating to inside and outside air quality, discussed during the BSRIA briefing in 2023.
Restoring Abbotsford's hothouse
Bringing the writer Walter Scott's garden to life.
Reflections on the spending review with CIAT.
Retired firefighter cycles world to raise Grenfell funds
Leaving on 14 June 2025 Stephen will raise money for youth and schools through the Grenfell Foundation.
Key points for construction at a glance with industry reactions.
Functionality, visibility and sustainability
The simpler approach to specification.
Architects, architecture, buildings, and inspiration in film
The close ties between makers and the movies, with our long list of suggested viewing.
SELECT three-point plan for action issued to MSPs
Call for Scottish regulation, green skills and recognition of electrotechnical industry as part of a manifesto for Scottish Parliamentary elections.
UCEM becomes the University of the Built Environment
Major milestone in its 106-year history, follows recent merger with London School of Architecture (LSE).
Professional practical experience for Architects in training
The long process to transform the nature of education and professional practical experience in the Architecture profession following recent reports.
A people-first approach to retrofit
Moving away from the destructive paradigm of fabric-first.
New guide for clients launched at Houses of Parliament
'There has never been a more important time for clients to step up and ...ask the right questions'
The impact of recycled slate tiles
Innovation across the decades.
EPC changes for existing buildings
Changes and their context as the new RdSAP methodology comes into use from 15 June.