Intumescent Coating DFT Calculator

Calculate required dry film thickness (DFT) for intumescent fire protection coatings on structural steel per BS 476 and EN 13381-8

Input Parameters

Results

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Required DFT
mm
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Estimated WFT
mm
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Number of Coats
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Coverage Rate
m2/L
Note: DFT values must be verified against the specific product assessment report (BS 476 test data or EN 13381-8 assessment). Section factor Hp/A is heated perimeter divided by area - higher values indicate lighter sections needing more protection.

Reference

BS 476 / EN 13381-8 Assessment Methods DFT depends on: section factor (Hp/A), fire rating, critical temperature Thin film (reactive): 0.25-5mm DFT, expands 20-50x when heated Thick film (epoxy): 2-25mm DFT, slower expansion WFT = DFT / Volume Solids Lower critical temperature requires thicker coating Higher section factor (Hp/A) requires thicker coating