This is what the supplier says about that. "One of the fire safety features of double-wall Type
B gas vent is that its outer wall, insulated by the
airspace beneath it, requires only 1" clearance to
combustible material in the structure". There is a firestop spacer manufacturers part number 40FS that may be ordered from the manufacturer to mount between the 2x4 studs.
"The source for the answers given by Grainger in Ask and Answer are based on the information provided with the question, which may not be complete or may not apply to other situations, and based on product literature and informational materials, the content of which is provided by Grainger’s product suppliers. Grainger disclaims liability for any information it provides in Ask and Answer which later may be alleged or determined by a court of law to be inaccurate or incorrect. The answers given by Grainger in Ask and Answer are not intended to replace or supplement any professional, engineering or other consultation services available to its product users. Always read, understand, and follow the product information and instructions provided by the manufacturer.
5 years, 11 months ago
Lincolnshire, IL, USA