I have a question about attic floor insulation. We have a chimney venting the furnace come through the middle of the attic. Although the rest of the attic floor is well insulated, there is a 4 inch gap around the perimeter of chimney creating an air draft coming from the basement. Does this gap have a function or could I seal it to minimize heat losses this winter?
COMMUNITY FORUM
If this is a masonry chimney, I can't think of any reason not to seal the gap at the framing with insulation. It would not be a fire hazard. For multi-wall metal pipe, I don't know, but would ask a stove shop for an opinion.
The energy portions of modern building codes require this gap to be sealed, not only for heat loss purposes, but also to create a firestop.
You can use either packed unfaced fiberglass or expanding foam insulation (which after January 2004) should be inflammable and firestopping charcteristics but read the can to be sure.
Contact your local code office for details.
You can use either packed unfaced fiberglass or expanding foam insulation (which after January 2004) should be inflammable and firestopping charcteristics but read the can to be sure.
Contact your local code office for details.
