A rated wall goes up. Mechanical runs ductwork through it. Three pages into Division 23, a clause nobody flagged reads: firestopping of penetrations by this trade is not included. Multiply that across every mechanical, electrical and fire protection division on the job, and the real shape of a firestopping bid comes into focus. It isn't sealing holes. It's reading disclaimers other people wrote and working out which ones default to you.
The material cost here is real but modest. The risk sits almost entirely in the assignment.
What lands here without argument
- Through-penetration firestopping — listed systems at every rated penetration. Pull the rated-assembly schedule and any penetration count specifically; the count is the bid, everything else is unit pricing against it.
- Fire-resistive joint systems — head-of-wall, wall-to-wall and floor joints in rated assemblies, priced to the movement capability the listed system actually provides, not a flat linear-foot rate.
- Joint sealants complete — interior and exterior, per the joint schedule: frame perimeters, control joints, dissimilar materials, wet areas, with the backer rod and primers the system specifies.
- Smoke seals — a different code trigger from fire rating, at non-rated but smoke-controlled assemblies. Easy to miss scanning only for rated walls.
Three places the paperwork goes soft
Expansion joint covers. Frequently split off to misc metals, or supplied direct by a specialty manufacturer with no installer named at all. Confirm whether the cover assembly itself, not just the fire-rated core behind it, is priced here or elsewhere. "Expansion joint" sounds like firestopping work, which is exactly how it ends up claimed by nobody.
Acoustic sealant. Most tenders have the drywall trade self-perform its own acoustic sealant at partition perimeters to hit an STC rating. Some specs centralize all sealant work, acoustic included, under this section instead. The two arrangements read almost identically on paper — check who the spec actually names before assuming drywall has it.
Curtain-wall perimeter fire containment. Safing at slab edges behind a curtain wall gets claimed by both sides about as often as it gets disclaimed by both. Glazing sometimes treats it as system continuity, since it touches their anchors and mullions. Firestopping sometimes treats it as someone else's wall. Whoever loses this one is short real linear footage around the entire building perimeter, at every floor.
What isn't yours, even when it looks close
- Firestopping carried by mechanical and electrical trades. The classic fight. Check the exact disclaimer language in Divisions 21 through 28 against 07 84 00. Losing this one costs twice: once assumed into someone's base bid, once as a change order nobody wanted to write.
- Applied fireproofing. SFRM and intumescent coatings on structural steel are priced and inspected nothing like through-penetration firestopping, despite the name overlap. Note it so the two scopes don't merge by accident at takeoff.
- Glazing sealants within systems. Structural silicone and weatherseal applied as part of curtain wall fabrication belongs to glazing, not to field sealant work here.
Four costs that never make it onto the rated-assembly schedule
- Third-party inspection. ASTM E2174 and E2393 language, destructive-test sampling rates, and, the part with real money attached, who pays when a sampled installation fails and has to be reopened.
- Engineering judgments for odd assemblies. An unusual substrate or an oversized penetrating item with no listed UL/ULC system needs a manufacturer's engineering judgment. That's added cost and lead time on a condition the drawings show once. Flag it before the submittal gets rejected, not after.
- Sealant colour and joint sizing. A custom colour match carries a real premium over stock. A joint outside a sealant's rated movement range needs a different product entirely, not more of the same one.
- Labelling and as-built logs. Required by code officials on larger institutional work, and genuine labour on a big job, not paperwork folded free into the install rate.
Where the boundary sits, trade by trade
| Trade | What to reconcile before you price |
|---|---|
| Mechanical & electrical trades | Sleeve sizes, locations and penetration schedules — confirm who firestops each one rather than assuming it defaults to you. |
| Drywall trade | Head-of-wall deflection details and rated shaft wall assemblies — the joint detail has to match what drywall actually built, not what the typical detail shows. |
| Glazing trade | Perimeter safing interfaces at curtain wall slab edges — the single most commonly double-claimed or double-disclaimed item on this list. |
| General contractor | Access before close-in — firestopping is always the last trade in and always squeezed by schedule; pull whatever access language the documents carry. |
The one sentence worth hunting for
Read the rated-assembly schedule once, for the penetration count. Then read every mechanical, electrical and fire protection division for the sentence that disclaims firestopping at their own work. It's there more often than not, and it decides whether this bid is complete more than the listed systems ever will.