Why firestopping is not automatically anyone's scope
A rated wall gets its rating from the assembly that was tested, not from the drywall alone. The moment a pipe, duct, conduit or cable tray passes through it, the opening has to be closed with a system that was tested for that specific penetration. Nobody assigns that work by default. The general default in the industry is that whichever trade cuts the hole is responsible for restoring the rated condition around it, unless the contract says otherwise.
That default works fine when one trade cuts one hole and closes it the same day. It breaks down on a real commercial floor plate, where a single rated corridor wall might carry sprinkler branch lines, data cabling, HVAC ductwork and electrical conduit, each installed by a different sub on a different week, and the drywall closing the wall around all of them last.
Where the gap shows up on a drywall package specifically
Drywall is usually the last trade to touch a rated wall before it disappears behind board, which puts us on the wrong side of a scope gap even when we did not create it.
- Sleeves and penetrations cut before board. Mechanical and electrical rough-in finishes, then leaves for the next task before the sleeve is sealed, and drywall is scheduled to board a day later.
- The head-of-wall joint. The gap between the top of a rated partition and the structure above is its own firestop detail, separate from any pipe or duct, and it is easy for a tender to leave it unnamed.
- The top of a shaft wall. Where a shaft wall or riser enclosure meets the floor above, the joint has to be sealed to match the rating, and it is rarely visible again once the floor above is occupied.
- Door frames in a rated partition. The frame itself, and the gap around it, are covered by a separate listing from the wall assembly and easy to assume is somebody else's detail.
- Retrofit penetrations added after drywall is complete. A cable tray added months later through a wall we already closed is not our scope to seal, but it is still our wall, and the tenant or property manager often assumes otherwise.
What a firestop detail actually requires
A firestop is only as good as the match between the tested system and the field condition. The system has to match the wall type, the size and material of the item passing through it, and the size of the gap left around it. A sealant or product that would work perfectly for a two-inch conduit through a two-hour wall is not automatically valid for a four-inch duct through the same wall. There is no single generic firestop that covers every penetration in a building.
What has to happen before the wall closes
Once board goes up, a penetration is out of sight. That makes sequencing the real control point, not just scope assignment on paper.
| Step | Whose scope, typically | Why it has to happen in order |
|---|---|---|
| Rough-in of pipe, duct, conduit or cable through the wall | Mechanical, electrical or the trade installing the item | Sets the exact size and location the firestop detail has to match |
| Sealing the penetration | Named trade or a dedicated firestop subcontractor | Has to be complete and, where required, inspected before the wall is closed |
| Head-of-wall joint at the top of the partition | Often the drywall subcontractor's scope | Part of the wall assembly itself, not a penetration through it |
| Boarding the wall closed | Drywall subcontractor | Cannot be undone without opening the wall back up |
| Labelling and documentation | Whoever installed the firestop | The only record once the wall is closed |
How to write the tender so nobody assumes someone else carried it
The fix is not complicated, it just has to be written down. A tender that names firestopping by penetration type, rather than as one line item, is the one that does not stall at inspection.
- State which trade carries the head-of-wall joint on every rated partition type, by tag, not as a general note.
- State which trade carries penetration sealing for each service: mechanical, electrical, plumbing, low voltage and any others expected on the project.
- Require the trade that cuts a penetration to notify the site superintendent before it is covered, so an inspection or a photo record can happen while it is still visible.
- Require labelling and a closeout package listing every rated wall penetration, the system used and who installed it.
- Decide before tender whether one dedicated firestop subcontractor will carry all penetration sealing, which removes the gap entirely but adds a trade to coordinate.
What we carry on ours
On our own fire-rated assemblies work, head-of-wall sealing and penetration firestopping are in our scope when the contract assigns them to us, and we coordinate with the mechanical and electrical trades so nothing is boarded over before it can be sealed and inspected. Where a dedicated firestop subcontractor holds the scope instead, we build to have the wall ready for them and confirm the sequence before board goes up.
If a tender is being written now, naming the firestop scope by penetration type before it goes out saves the argument that usually shows up at inspection instead.