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Fire Door Guide
Fire Door Seals & Intumescent Strips Explained
Fire door seals are components used around suitable fire door assemblies to help manage the gaps between the door leaf and frame. Intumescent seals and smoke seals perform different functions, and some products combine both in one strip.
Use this guide as a practical introduction, then check the relevant tested system and manufacturer documentation before selecting or installing a product.
Use This Guide
Understand the principle first
Use this guide as a practical introduction, then check the relevant tested system and manufacturer documentation before selecting or installing a product.
Fire Door Guide
Quick Guide
Fire door seals are components used around suitable fire door assemblies to help manage the gaps between the door leaf and frame. Intumescent seals and smoke seals perform different functions, and some products combine both in one strip.
Key Points
What You Need to Know
Intumescent Seals
React to heat and expand.
Smoke Seals
Restrict cold smoke through operating gaps.
Combined Seals
Can provide both functions in one product.
Correct Size
Seal dimensions and position matter to the door assembly.
Key Principle
What Are Intumescent Fire Door Seals?
Intumescent seals contain material that expands when exposed to heat. In a suitable fire door assembly, this expansion helps protect gaps around the door leaf and frame as the fire develops.
Seal dimensions and locations form part of the fire door evidence and should not be changed without confirming that the replacement is appropriate.
Practical Guidance
What Are Smoke Seals?
Smoke seals are intended to limit the passage of smoke through the operating gaps around a door. They may use brushes, blades or other sealing methods depending on the product.
An intumescent-only strip should not automatically be treated as providing smoke control unless the product is designed and specified for that purpose.
Selection & Application
Combined Intumescent and Smoke Seals
Many fire door products combine an intumescent core with a smoke seal. This can provide both fire-related and smoke-control functions where required by the door specification.
Replacement products should match the required size, type, position and performance of the door assembly.
Important Detail
Inspection and Replacement
Damaged, painted-over, missing or poorly fitting seals can affect the intended performance of the door assembly. Regular checks should consider the seals alongside gaps, hinges, closers, glazing and other door components.
When replacing seals, verify the door specification or supporting evidence rather than choosing a strip solely by appearance.
Relevant Products
Explore Related Product Ranges
Use the guide to understand the application, then browse the relevant Fire Protection Direct product categories.
Frequently Asked Questions
Frequently Asked Questions
It is a heat-reactive seal fitted to a suitable fire door assembly to help protect the gap between the door leaf and frame during a fire.
Intumescent material reacts to heat, while a smoke seal is intended to restrict smoke through the operating gap. Some products combine both.
No. The replacement should be appropriate for the specific fire door assembly and its supporting evidence.
Painting or coating seals can affect some products. Follow the door and seal manufacturer guidance.
Yes. Fire doors should be managed and inspected appropriately, including their seals and other critical components.
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