Wood framing clearance required where a masonry chimney passes through the roof opening is how many inches?

• A. 2 inches
• B. 1 inch
• C. 1/2 inch
• D. 1-1/2 inches

Answer: (A)

A two-inch clearance from wood framing is required where a masonry chimney passes through a roof opening because heat from the masonry can transfer to combustible wood. This gap provides a safe buffer and makes room for noncombustible protection around the chimney, helping to prevent ignition of surrounding framing and allowing proper firestop and flashing installation for a weatherproof, fire-resistant assembly. In practice, you frame the roof opening with a noncombustible chase or surround and maintain that two-inch gap, sealing and flashing as needed. Gaps smaller than two inches raise the risk of heat transfer to wood; only use a smaller clearance if the chimney system’s manufacturer specifies an alternate clearance and provides the appropriate protective details.