We are in a house built in the early 70s which has a mansard roof. Two years ago we had the original shingles replaced with new ones because they were showing signs of age and curling. The curling was particularly bad on the front of the house which faces west.
Now that we have the new shingles on, they look much better but we are STILL having issues with curling. On sunny days, the shingles on the west side of the house (front) tend to "puff" out like they are incorrectly adhering. Since this appears to be temperature related I thought it might have something to do with the venting of the vertical portion of the mansard roof.
I went up into the attic, and it appears as though there is ~4" of pink fiberglass insulation on the ceiling, and then another ~4" of insulation (not fiberglass) has been blown in on top of that. From what I can tell, the "blown in" insulation goes right up to the edge of the roof, thereby blocking any vertical flow of air coming up from the soffit.
Q1: Does there need to be a space between the vertical and horizontal portions of the mansard roof?
Q2: If so, how frequent do the spaces need to be (between every truss, every other truss, two or three across the span)?
Q3: Does it seem plausible that this is causing the problems with our shingles? If not, what else could it be?