The previous owners of our 80-year-old house had put insulation in the attic. Leaky shingles on the roof and a bathroom vent that shot up directly into the attic has caused the insulation to flatten considerably. We are going to replace the shingles and install a bathroom exhaust. Once that is done, is it necessary to replace the flattened insulation, or is it possible to somehow salvage it?

A year ago I built a detached garage next to my house, with a cement floor and 2x6 construction walls. I did a meticulous job with vapor barriers. The problem is that in each corner, about 15 cm (6 in.) above grade, the wall is soaking wet. Outside, the edges are bone dry. What's the problem?

I installed an addition to my house this past summer using rigid foam panels. The end result is that where the old and the new walls meet there is exposed brick on the inside of the house which turned into ice this winter. What is causing it and what can I do to repair it?