It's a good thing you spotted that dirt, which is proof that a draft is moving into the attic from the house below. The insulation acts as a filter, trapping the material moving by in the airstream.

Q: What is the best way to waterproof my chimney? The bricks tend to absorb water, and I get some leaks. A: Bricks do not usually absorb water, unless the bricks are common and old. In the old days ...

Whether store-bought or handmade, fabric draft stoppers — long, rectangular cloth tubes stuffed with soft, pliable filling — are a stylish and simple way to block drafts that leak through cracks and ...