Sleeping room requirement

Ontario Building Code Sentence 3.2.4.18.(5) requires the fire alarm audible signal to reach not less than 75 dBA in a sleeping room in a building of residential occupancy, with any intervening doors between the device and the sleeping room closed. Sentence 3.2.4.18.(6) separately requires audible signal devices in sleeping rooms in a residential or care occupancy to emit a low frequency signal. Note the scope split: NBC 2020 applies the 75 dBA figure to residential or care occupancy, while the printed Ontario text limits it to residential only. The doors closed condition is part of the requirement itself, and it is the reason sounders end up inside dwelling units rather than only in the corridor.

Last updated: September 2026

The two sentences that govern a sleeping room

A sleeping room is treated as a special case in Ontario's Article 3.2.4.18 because the occupant is asleep, which is the one condition under which the ordinary floor area level is not good enough to rouse anybody.

Sentence	Requirement	Occupancies caught
3.2.4.18.(5)	Not less than 75 dBA in the sleeping room, intervening doors closed	Residential, in the printed Ontario text
3.2.4.18.(6)	Device must emit a low frequency signal, no frequency stated	Residential or care

Everywhere else in the building, the general rule in Sentence 3.2.4.18.(7) applies instead: not less than 10 dBA above ambient and not less than 65 dBA. See audibility for the general case.

Doors closed is not a footnote

The measurement condition is written into both sentences. The level has to be there with any intervening doors between the device and the sleeping room closed.

That single condition drives most of the design decisions on a residential job, because it removes the easy option. A corridor sounder that comfortably makes 75 dBA in an open doorway will not necessarily make it through a closed suite entry door and a closed bedroom door. Two doors and a bit of hallway are a serious attenuator, and once the numbers do not work from the corridor, you are installing devices inside the unit.

That in turn is what pulls in the whole in-suite wiring question, because devices inside a dwelling unit have to be arranged so a fault at one does not impair the devices serving other suites. Ontario Sentence 3.2.4.18.(9) states that outcome, and the two compliant routes are set out in the two ways to wire residential audibility. The hardware answer on the Class B route is the suite fault isolator.

The scope split, and why it matters

NBC 2020 applies its 75 dBA sleeping room sentence to a building of residential or care occupancy. The Ontario text in the free 2024 Compendium says residential occupancy.

On the face of the printed Ontario text, a sleeping room in a care occupancy is therefore not caught by the 75 dBA sentence. What remains for it is the general floor area rule, 10 dBA above ambient and not less than 65 dBA, plus whatever the design, the specification or the authority having jurisdiction requires.

Meanwhile Sentence (6), the low frequency requirement, covers residential and care. Same article, one sentence apart, two different scopes.

We are not going to tell you that a care occupancy sleeping room needs only 65 dBA. That is what the printed text supports, and it is also the kind of drafting outcome that gets fixed in an amendment document. The amendment document actually in force is dated 17 July 2026 and is not published online. If you are working on a care occupancy, raise it with the AHJ rather than assuming either number.

What gets tested, and what that costs you

The level is proven on site, not on paper. Expect the verifier working to CAN/ULC-S537 to take readings inside sleeping rooms with the doors closed, which means access to occupied units. On a retrofit in a tenanted building that is a scheduling problem that has to start weeks before the test date, not a line on a checklist.

What we do not print here

You will see a figure quoted in the trade for how much sound pressure a closed door removes. We are not repeating one. That data sits inside CAN/ULC-S524, which is copyrighted and sold, and we do not reproduce paywalled standard text or substitute the American equivalent.

The related device requirement is covered separately under the low frequency signal, and the maximum permitted level, which is genuinely unsettled in the printed Ontario text, is worked through in fire alarm audibility in Ontario.

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