NBCC 2020 Fire Separation

[KB4444]

NBCC 3.6.2.1.(6) requires a service room to be "separated from the remainder of the building by a fire separation having a fire-resistance rating not less than 1h."

If a service room is located in the corner of an open building, and has a small mezzanine above it not counting as a storey, does the exterior wall surrounding the service room need to have 1 h fire-resistance rating? Or just the interior walls and ceiling/floor of the service room open to the rest of the floor?

In theory the exterior wall could carry the fire upwards to the remainder of the building, but I don't know if that is the purpose of this clause requirement. The exterior wall does not require any fire rating otherwise, meaning only the small area of the exterior would be different.

 

[SWComposites]

well, regardless of the code, it makes no sense to have only 2 of 4 walls be fire resistant.

 

[jayrod12]

That's really a better question for an architect. That's why they get to ask for the big fees.

As far as I've understood it however, you need to separate it from adjacent occupancies. Exterior is not considered an occupancy unless it's a designated area like a patio.

There are other potential code triggers for the exterior wall being rated, or non-combustible, but those are often due to proximity to adjacent properties/buildings, and less about the use of the new building.