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Fire protection engineering · article 6 of 10

Intumescent vs cementitious fireproofing

Thin, decorative intumescent coatings or economical cementitious sprays? A side-by-side comparison of appearance, ratings, durability, application and cost to choose the right fireproofing.

World Steel engineering team · Updated 2026-10-16 · 2 min read

Fire protection systems compared (illustration)

Two different principles

Intumescent coatings are thin films that expand in a fire. Cementitious fireproofing (sprayed fire-resistive materials, SFRM) is a thick layer of cement or gypsum with light aggregates that insulates from the start.

Comparison

Intumescent vs cementitious
CriterionIntumescentCementitious (SFRM)
AppearanceSmooth, paint-like, any colourTextured – usually concealed
Typical ratings30–120 min (epoxy longer)1–4 h
WeightNegligibleAdds load
ApplicationShop or site, airless spraySite, wet spray
DurabilityGood with topcoat; epoxy very goodLow-density grades fragile; dense grades robust
Cost at long ratingsRises steeplyUsually the lowest
InspectionDFT gaugesThickness and density (ASTM E605)

How to choose

  • Exposed, architectural steel → intumescent.
  • Concealed steel above ceilings, long ratings → cementitious.
  • Export steel that should arrive protected → shop-applied intumescent.
  • Hydrocarbon fires → epoxy intumescent or dense cementitious systems tested for them.

Most projects combine both – and boards for columns in public areas.

FAQ

Which is cheaper?

For short ratings on heavy sections intumescent can be competitive; for long ratings on concealed steel cementitious is usually cheaper.

Need the thickness and cost for your project?Send the member schedule and fire ratings – our engineers prepare a fire protection proposal.
Request proposal

Preliminary calculations are provided for estimation purposes only. Final coating thickness and fire protection system selection must be verified against the approved product documentation, applicable project requirements and relevant engineering assessments.

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