Fire-resistance rating of the fire separation required by Sentence 3.3.5.6.(1) [applying to the separation of storage garages], where:

• the fire separation is located between a dwelling unit and an attached storage garage containing not more than 5 vehicles,
• the dwelling unit and the attached storage garage are sprinklered,
• the dwelling unit and the attached storage garage are separated from the remainder of the building in conformance with Sentences 3.3.4.2.(1), (2) and (3),
• there are no air duct systems connecting the storage garage and the dwelling unit,
• the construction between the storage garage and the dwelling unit provides an effective barrier to gas and exhaust fumes, and
• every door between the storage garage and the dwelling unit is:
  • tight fitting and weather-stripped to provide an effective barrier against the passage of gas and exhaust fumes,
  • fitted with a self-closing device, and
  • not located in a room intended for sleeping.

This applies to floor areas or parts of floor areas used or intended for use as residential occupancies, in buildings described in Sentence 1.3.3.2.(1) of Division A.

This also applies to tents and air-supported structures, as stated in Sentences 3.1.6.1.(1) and 9.10.1.2.(1).

To exempt separations between a dwelling unit and an attached garage from the fire-resistance rating requirements of Sentence 3.3.5.6.(1) on the basis that sufficient conditions are in place to minimize the threat to the occupants of the dwelling unit posed by fire and exposure to vehicle exhaust fumes, and the dwelling unit and the attached storage garage are sprinklered.

This [the separation and sprinkler protection] is to limit the probability that a fire involving the garage will spread to the dwelling unit, which could lead to harm to persons.

This [the door requirements, fume barrier and prohibition of air ducts] is to limit the probability that vapours will migrate from the garage into the dwelling unit, which could lead to their accumulation and subsequent ignition by a nearby ignition source, which could lead to a fire or explosion, which could lead to harm to persons.