When does code require a fire damper vs. a smoke damper vs. a combination damper in ductwork?

Q: When do you use intumescent coating instead of spray-applied cementitious fireproofing on structural steel?

Intumescent is specified where the steel stays visible — lobbies, atriums, exposed beams in restaurants — because it cures to a thin paint-like finish and only swells into an insulating char during a fire. Cementitious SFRM is the cheaper workhorse for concealed steel above ceilings and behind walls; it goes on thick and rough but is fully UL-listed for 1–4 hour ratings at a fraction of the per-square-foot cost.

Q: How do I pick between firestop sealant, mortar, and wrap strip for a wall penetration?

The choice is driven by the penetrant and the annular space. Silicone or intumescent sealant handles metallic pipe, conduit, and small cable bundles. Mortar fills large openings or multiple penetrants in concrete and masonry. Intumescent wrap strips are mandatory around combustible penetrants — PVC drain, CPVC, insulated copper — because they expand on heat and crush the melted pipe to re-seal the opening per the UL system listing.

Question

When does code require a fire damper vs. a smoke damper vs. a combination damper in ductwork?

Accepted Answer

IBC and NFPA 90A trigger a fire damper at every duct penetration of a fire-rated wall, floor, or shaft. Smoke dampers are required where ducts cross smoke barriers or where an engineered smoke-control system needs to compartmentalize. Combination fire/smoke dampers consolidate both functions and are the default in assemblies that are both rated and smoke barriers — typically corridor walls and shaft enclosures in high-rise construction.

When does code require a fire damper vs. a smoke damper vs. a combination damper in ductwork?

Answers