Question: Hello, I have a quick question that if you could answer for me it would be greatly appreciated. What is the closest distance away from the exhaust pipe on a pellet stove that walls can be. My situation is this.... I have a modular home with 12" trusses under the floor, on top of a poured concrete foundation. I would like to vent a pellet stove over the top of my foundation, between trusses to the outside, thus saving drilling through the foundation. I could drill through the outer joist (2x12) and vent through the wall (Easier to drill wood). Is this a possibility? Answer: If the Pellet Stove takes a 3" vent, and the clearance to Pellet Vent (L vent) is 2 inches, then you will need a 7 inch round or square hole to install the wall thimble kit. This may vary by manufacturer, but should fit into your situation in just about any case. Of course, make certain you are OK removing the truss structure at that point. Be sure to check the stove manufacturers instructions as well as the pipe manufacturer. Go with the larger of the two recommended clearances.