Glossary / intumescent

intumescent

A material that swells when heated and can close a gap. Some listed vents use intumescent cores. A paint-on coating is not an Oregon R327 wall covering.

Last verified 2026-08-23. JSON (CC BY 4.0)

Do not use as a synonym: fireproof paint.

Related

• listed
• ignition resistant
• vents
• astm-e2886
• Mesh versus listed vents

Where this term is used

6 guides use this term.

• How an intumescent vent closes
• How to read an ICC-ES report
• Mesh versus listed vents
• Net free area after mesh or a listed core
• OSFM 8165 vent applications
• Wall penetrations, hose bibs, and linesets