What is the proper clearance distance between a single-wall metal flue pipe and combustibles?

What is the proper clearance distance between a single-wall metal flue pipe and combustibles?

• A. 12 inches
• B. 3 inches
• C. 9 inches
• D. 6 inches

Answer: (D)

Heat clearance around vent piping is about keeping combustible materials away from hot surfaces. A single-wall metal flue pipe carries significant heat, so the code requires a six-inch gap to combustibles to reduce the risk of ignition. This distance is the minimum safe separation for standard single-wall pipe. Using listed insulated or double-wall vent systems could change the requirement, but for plain single-wall pipe the six-inch spacing is the rule. The other options are either too small to meet safety requirements or unnecessarily larger for this case; six inches provides the safe, code-compliant spacing.

Heat clearance around vent piping is about keeping combustible materials away from hot surfaces. A single-wall metal flue pipe carries significant heat, so the code requires a six-inch gap to combustibles to reduce the risk of ignition. This distance is the minimum safe separation for standard single-wall pipe. Using listed insulated or double-wall vent systems could change the requirement, but for plain single-wall pipe the six-inch spacing is the rule. The other options are either too small to meet safety requirements or unnecessarily larger for this case; six inches provides the safe, code-compliant spacing.