The clearance to combustible materials for double wall stove pipe, such as standard drywall or wood, is 6" to walls and 8" to ceilings. Clearance to non-combustible materials is 0", but pipes should not actually touch cement, bricks or other non-combustibles.
Rockford's double wall chimney pipe has a limited lifetime warranty. It is manufactured with a 24 gauge black steel outer pipe and a .015", 430 alloy stainless inner liner. The double wall construction keeps the outside cooler and thus allows you to reduce both wall and ceiling clearances. Compatible with our black stove pipe along with Ventis, Champion, and Nexvent.