BCAB #1463 - Ventilation of Roof Spaces, Sentences 9.19.1.1.(1) & 9.19.1.2.(1)

April 14, 1998

BCAB #1463

Re: Ventilation of Roof Spaces, Sentences 9.19.1.1.(1) & 9.19.1.2.(1)

Project Description

The project in question is a church and school constructed under Part 3 of the BC Building Code. Part of the roof for the building is composed of TJL joists set at a 8:12 pitch with plywood sheathing attached directly to the top cord and gypsum board attached directly to the bottom. It is proposed to completely fill the roof space with fiberglass insulation and not vent the roof space. The appellant has agreed with the building official that Part 9 requirements for roof venting are appropriate to this building.

Reason for Appeal

Sentence 9.19.1.1.(1) requires every roof space above an insulated ceiling to be ventilated with openings to the exterior. Sentence 9.19.1.2.(1) specifies the minimum vent area for roofs constructed of joists with insulation below the roof sheathing.

Appellant's Position

The appellant contends that venting is not required for this roof because there is no roof space above the ceiling. The insulation is installed to the full depth of the joists, leaving no space that would require venting.

Building Official's Position

The building official maintains that Sentence 9.19.1.2.(1) requires the roof space between the roof sheathing and ceiling membrane to be vented and the joist space cannot be completely filled with insulation.

Appeal Board Decision #1463

It is the determination of the Board that the roof space must be ventilated in accordance with Subsection 9.19.1. The space between the ceiling membrane and the roof sheathing is a roof space (see Attic or roof space in Article 1.1.3.2.) regardless of it being filled with insulation.

George R. Humphrey, Chair