B-Type gas vent pipes should have a minimum of 1″ clearance between it and any combustion able material. Often times when roofs are being replaced, the vent pipe gets moved out of position contacting the roof sheathing causing an unsafe condition. The vent pipe should be repositioned back into it’s origninal position or the wood sheathing trimmed to meet this proper clearance.

Improper Gas Vent Pipe Clearance

Improper Gas Vent Pipe Clearance