What you should insulate and when you should insulate depends on a variety of factors. For existing houses, typically, the attic, crawlspaces and unfinished basements are important, with the attic being the priority. Poorly insulated attics can damage the inside of the structure and the roof and shingles. Attics with existing insulation can be ‘topped up’ until the desired R-value is reached.
For new construction and renovations, we install insulation once the electrical and plumbing is in place.