Home › Firestop answers

Firestop answers

What does the National Building Code of Canada require for firestopping?

By Corey Beckett, Founder & Principal · Published 28 October 2026

Which code this page is based on

The National Building Code of Canada (NBC) is a national model code. Provincial and territorial governments have the authority to regulate building design and construction, and may adopt the NBC without change or with modifications to suit local needs (NBC 2020, Preface). This page cites NBC 2020 and notes where NBC 2025 differs.

The 2025 edition of the NBC was published at the end of 2025. The firestop articles discussed here (3.1.8.3 and 3.1.9.1 to 3.1.9.4, and 9.10.9.2 and 9.10.9.6 for houses and small buildings) have the same wording in NBC 2020 and NBC 2025, apart from how NBC 2025 spells the title of ASTM E2307. What changed in 2025 is the edition of the test standards the code references in Division B, Table 1.3.1.2: CAN/ULC-S115:2023 in place of CAN/ULC-S115-11, and ASTM E2307-20 in place of ASTM E2307-15b. Check which code and which edition apply to your project with the authority having jurisdiction.

CAN/ULC-S115 clause numbers on this page are from CAN/ULC-S115:2023, the edition NBC 2025 references; NBC 2020 references the 2011 edition.

Penetrations: an F rating as the baseline

A building service or structural element penetrates an assembly when it passes into or through it (Note A-3.1.9.). A through-penetration passes through the whole assembly; a membrane penetration goes through one face of it, such as a wall board or a ceiling. Article 3.1.9.1 covers both.

Penetrations of a fire separation, or of a membrane forming part of an assembly required to have a fire-resistance rating, must be either:

• sealed by a firestop that, when tested to CAN/ULC-S115, has an F rating not less than the required fire-resistance rating of the fire separation, or
• cast in place, where the penetrating item is steel, ferrous, copper, concrete or masonry (Sentence 3.1.9.1.(1)). “Cast in place” means there are no gaps between the penetrating item and the assembly it passes through; the code's note describes it as a typical means of firestopping a service penetration through a concrete slab or wall (Note A-3.1.9.1.(1)(b)).

In the CAN/ULC-S115 fire test, the F rating is the time the firestop stays in the opening without letting flame pass through it and without flaming on any element of the unexposed side (CAN/ULC-S115:2023, clause 12.2).

Ducts, electrical outlet boxes, pipes, totally enclosed raceways, optical fibre cables, electrical wires and cables, and other similar service equipment may penetrate on that basis (Sentence 3.1.9.2.(1)). Article 3.1.9.1 exempts two items from the firestop requirements of Sentences (1) to (3): sprinklers, where the annular space is covered by a metal escutcheon plate in accordance with NFPA 13, and fire dampers installed in conformance with NFPA 80, unless they are specifically designed with a firestop (Sentences 3.1.9.1.(4) and (5)).

Where the code asks for an FT rating

An FT rating adds a temperature limit to the F rating: during the fire test, no thermocouple on the unexposed side of the firestop, including those on the penetrating items, may rise more than 181 °C above its starting temperature (CAN/ULC-S115:2023, clauses 5.3 and 12.3). The NBC requires an FT rating not less than the fire-resistance rating for:

• penetrations of a firewall (Sentence 3.1.9.1.(2));
• penetrations of a horizontal fire separation required by Article 3.2.1.2, the floor and roof assemblies over a basement storage garage that is treated as a separate building (Sentence 3.1.9.1.(2)), with an F rating permitted for service penetrations contained within the cavity of a wall above and below that separation (Sentence 3.1.9.1.(6));
• penetrations of the fire separation below a horizontal service space or other concealed space that is not divided at a vertical fire separation, as Sentence 3.6.4.2.(2) permits (Sentence 3.1.9.1.(3)), with an F rating permitted for some service penetrations under Sentences 3.1.9.1.(6) and (7);
• outlet boxes in the membrane of a fire-rated assembly, and combustible outlet boxes (Sentences 3.1.9.3.(1) and (2)). Small noncombustible boxes in a vertical fire separation or a membrane are exempt, except where Sentences 3.1.9.1.(2) and (3) apply: not more than 0.016 m² each, not more than 0.065 m² in total in any 9.3 m² of surface, with an annular space of not more than 3 mm (Sentence 3.1.9.3.(3)). Boxes on opposite sides of a vertical fire separation need a horizontal separation of at least 600 mm, a fire block conforming to Article 3.1.11.7, or an FT-rated firestop on each box (Sentence 3.1.9.3.(4));
• the joints that keep a rated fire separation continuous (Sentence 3.1.8.3.(3)), covered below.

Combustible piping: check the test pressure

Combustible drain, waste and vent piping may penetrate a rated fire separation, or the membrane of a rated assembly, if it is sealed by a CAN/ULC-S115 firestop with an F rating not less than the fire-resistance rating required for the fire separation, and is not located in a vertical service space. In buildings more than 3 storeys in building height, that firestop must have been tested with a pressure differential of 50 Pa between the exposed and unexposed sides, higher on the exposed side (Sentence 3.1.9.4.(4)). In a building of any height, a penetration of a fire separation that incorporates a transition between combustible and noncombustible drain, waste and vent piping needs the same 50 Pa test, except as Sentence 3.1.9.4.(8) provides (Sentence 3.1.9.4.(7)).

CAN/ULC-S115's standard test pressure is a minimum of 2.5 Pa, and a higher pressure can be run as a “unique pressure condition” (CAN/ULC-S115:2023, clauses 5.5.2 and 5.6). So check that the listing, or the test report, shows the system was tested at 50 Pa.

Joints: what changed in NBC 2020

NBC 2015 required the continuity of a fire separation to be maintained where it abuts another fire separation, a floor, a ceiling, a roof or an exterior wall assembly, but named no fire test or rating for doing so (NBC 2015, Sentence 3.1.8.3.(4) and Table 1.3.1.2). Since NBC 2020:

• where a fire separation with a fire-resistance rating abuts another fire separation, a floor, a ceiling or a roof, its continuity must be maintained by a firestop with an FT rating not less than the fire-resistance rating of the abutting fire separation, tested to CAN/ULC-S115 (Sentences 3.1.8.3.(2) and (3));
• joints in a horizontal plane between a floor and an exterior wall, the perimeter joint, must be sealed by a firestop tested to ASTM E2307 with an F rating not less than the fire-resistance rating of the horizontal fire separation (Sentence 3.1.8.3.(4));
• joints between ceilings and walls, floors and walls, and walls at corners are exempt where they consist of gypsum board attached to framing members and arranged to restrict the passage of flame and smoke (Sentence 3.1.8.3.(5)).

Joint systems are also tested for movement. The code's explanatory note says joint firestop systems can be tested and listed as static or dynamic, that dynamic systems are cycled through their movement before the fire test, and that most joints between fire-resistance-rated assemblies, other than those between loadbearing elements, experience some movement over the life of the building (Note A-3.1.8.3.(2)). The listed movement capability has to suit the joint.

NBC 2020 changed penetrations too. NBC 2015 tied the F rating to the fire-protection rating required for a closure in that fire separation, for example 45 minutes in a 1-hour fire separation (NBC 2015, Sentence 3.1.9.1.(1) and Table 3.1.8.4), and, for penetrations covered by Sentence 3.1.9.1.(1), allowed cast in place whatever the penetrating item was made of. NBC 2020 requires an F rating not less than the fire separation's required fire-resistance rating, and limits cast in place to steel, ferrous, copper, concrete or masonry items.

Houses and small buildings (Part 9)

Part 9 carries equivalent joint requirements, which also apply where a fire separation abuts a smoke-tight barrier (Sentences 9.10.9.2.(3) and (4), with the gypsum board exemption in Sentence 9.10.9.2.(6)), and the same F rating for penetrations (Clause 9.10.9.6.(1)(a)), with two more options: a steel, ferrous, copper, concrete or masonry item may be tightly fitted as well as cast in place, and a penetration may be “sealed to maintain the integrity of the fire separation” (Clauses 9.10.9.6.(1)(b) and (c)). The explanatory note gives mineral wool, gypsum plaster and Portland cement mortar as examples of generic materials for that last option (Note A-9.10.9.6.(1)). Penetrations of a firewall still need an FT rating (Sentence 9.10.9.6.(2)), and penetrations by piping, outlet boxes and service equipment have their own rules (Articles 9.10.9.7 and 9.10.9.8).

After occupancy: the National Fire Code

Once the building is in use, the National Fire Code of Canada governs its maintenance. Where fire separations are damaged so as to affect their integrity, they must be repaired so that their integrity is maintained, and materials used to provide fire protection that are damaged or removed must be repaired or replaced (NFC 2020, Division B, Article 2.2.1.2). Unless the code says otherwise, the owner or the owner's authorized agent is responsible for carrying out the Fire Code (NFC 2020, Division C, Article 2.2.1.1).

Knowing which firestop systems a building has, and what they were installed to, lets a repair match the tested system.

This page explains the national code and the inspection standards in general terms. It is not a code interpretation, a design opinion or engineering advice for a particular building. The code in force in your province or territory governs, and the authority having jurisdiction decides what is acceptable on a project. PFS is not an engineer, an architect or the authority having jurisdiction, and does not issue, request or procure engineering judgments.