Furnace Exhaust Clearance

[Kenneth W. Blair]

Does this insulation need to be clear of the furnace exhaust vent?

[Charley L. Bottger]

Originally Posted by kblair1

Does this insulation need to be clear of the furnace exhaust vent?

In this state double or single wall pipe must be at least 4 inches from combustible.

[ccbrands1]

i believe the standards are 1" clearance for B vent and 6" for single wall vent.

of course, as Charley pointed out, state or local requirements may reign supreme.

[Jeremy Tucker]

CC has it right for the minimum clearance from combustables. 1" for B vent, 6" for C vent (single wall), BUT... the clearance for single wall CAN be reduced to 1" if a heat shield (sheet metal) is installed between the vent and the combustable surface. But to be sure, check local regulations.