Re: Insulating attached garage
for the soffit vents, this is easily solved, you just need a large hole saw to use in a corded drill, drill some holes in the closed soffit in between rafters (look for the nails trough the plywood or boards)from there install perforated vinyl soffit.
for the roof you wont have to remove any shingles but you will have to remove the ridge cap. once thats done snap a chalkin line 2" down from the peak all the way along the roof on both sides stopping 2 ft in from the ends. now cut out the sheathing and shingles with a circular saw along the chalk line but set the depth of the saw blade to the equivalant of the thickness of the shingles and the roof sheathing so to not overcut into the rafters. from there remove the waste sheathing and install the ridge vent.. next put down new ridge cap and your good to go
fire up the saw and make some dust