Do I still have to use a metal shield and leave an air space around a Type B vent pipe if it is passing through a drywall ceiling and fiberglass batt attic insulation, both of which are noncombustible?

A.Mike Hamlin, an hvac contractor in Meredith, N.H., responds: The short answer is yes, because no manufacturer or code official would want to leave the decision of whether or not the air space is necessary up to an installer or home­owner. The installation instructions for the AmeriVent B-vents we typically install specifically call for a...

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