We’re looking for advice regarding venting a tin roof. We have a 3 :12 shed roof, and the house is located in Quebec.

Above the roof sheathing, we are planning to run 1″x4″ hemlock strapping up the trusses, followed by horizontal 2″x4″ strapping under the tin.

– our thought was to bring up the sheathing from the lower edge of the deck to allow for the soffit vents (near the outer edge) to supply the air required for above the sheathing / tin.

It occurred to me, however, that sharing the air supply of the soffit vents (despite their adequate sizing) could possibility disrupt the effectiveness of the roof (under sheathing) ventilation, but I don’t see any other method of venting the tin on a building with a fascia board.
Perhaps a divider within the soffit on the lower end the roof would serve to designate air supply to each area – above and below the sheathing, with the bulk of air going to supply ventilation under the roof sheathing.

For our soffit vents, we had planned on ample air supply – 1×4’s alternating with screened spaces of 4″ all the way around.

Any advice greatly appreciated.

Jessie