Firestopping is the layer the inspector reads off the wall. Every cable and every conduit that crosses a fire-rated wall, fire-rated floor, or smoke barrier needs a listed firestop system that matches the assembly’s hour rating. The system is the combination of the penetrating item, the surrounding construction, and the listed firestop assembly. Skip the system, mismatch the rating, or fail to identify the install and the AHJ fails the inspection regardless of how much sealant went into the hole.
The governing standards
When the standards apply
Every penetration through a fire-rated assembly. The standards below define what counts as a listed firestop system and how to identify it in the field.
The standards in detail
Selecting the right firestop system
When the rule applies
Every fire-rated penetration on the project. The system is the combination of penetrating item, surrounding construction, and listed assembly. The ULC system number on the listing has to match the as-installed condition exactly. A 2-hour wall has to use a 2-hour-rated system. A metallic conduit has to use a system listed for metallic conduit. A cable bundle has to use a system listed for cable bundles, not for conduit.
The spec for common security work penetrations
Field note
Penetration sizing and annular space
When the rule applies
Every firestop install. The annular space (the gap between the penetrating item and the wall opening) is part of the listed system. Wrong gap and the system listing does not apply.
The spec
Fire-rated walls versus smoke barriers
When the rule applies
The building code distinguishes between fire-rated assemblies (rated for fire spread) and smoke barriers (rated for smoke spread). Some assemblies are both. The firestop system has to address whichever rating the assembly carries.
The two ratings and how they differ
Fire rating
The assembly’s resistance to fire spread for a specified time (1 hour, 2 hour, 3 hour, 4 hour). Tested under CAN/ULC-S101. Defines which firestop systems are eligible for the penetration.
Smoke rating
The assembly’s resistance to smoke spread. Some assemblies are smoke-rated without being fire-rated (some corridor walls, some elevator-shaft partitions). Smoke-rated firestop systems use products that maintain a smoke seal even before intumescent expansion.
Combined fire and smoke barrier
Most institutional building’s fire-rated walls are also smoke barriers. The firestop system has to be listed for both. Many 3M and Hilti systems carry dual listings for this case.
Field note
Outlet box penetrations and back-to-back boxes
When the rule applies
Every outlet box in a fire-rated wall. The box itself disrupts the wall’s fire resistance unless it is wrapped or pad-protected.
The spec
Field note
Through-floor penetrations and riser slots
When the rule applies
Vertical conduit and cable runs between floors. Every floor penetration is a fire-rated penetration unless the floor is non-rated (rare in institutional buildings; check the architectural drawings).
The spec
Field note
Identification and inspector-readable labelling
When the rule applies
Every firestopped penetration on the project. The AHJ reads the ULC system number off the label, reads the hour rating off the label, and verifies the as-built condition matches the listing. Without inspector-readable identification, the firestop fails inspection regardless of how well it was installed.
The spec
Field note
Repair and modification of existing firestops
When the rule applies
Any retrofit or renovation that disturbs an existing firestopped penetration. The integrator who pulls cable through the existing seal owns the resealing.