soffit and ridge vents and/or/with attic fan?
We'll be replacing our two story contemporary saltbox homes's roof. The roof is ventilated with continuous soffit and ridge venting. We also have a non working attic fan that has burned out two motors. Our home is 20 years old and this will be the third roof. Because of premature failure, Celotex replaced the shingles approximately 10 years ago. We've also experienced ice dams twice on the cathedral ceiling portion of the roof.
After reading the postings on this forum, I assume the roof problems: early failure, ice dams, and leaking happened because the vent system is not working. Maybe there is insufficient air flow up the bays between the rafters? What needs to be done to make sure the soffit and ridge venting is working, especially in the cathedral ceiling part? And once the venting is working, should the attic fan be replaced or is it not necessary with soffit and ridge venting? About 20 feet of the roof is a half story higher than the other 25 feet; should there be two attic fans at the highest part of each ridge?
Also, over the attic part, the roof appears to be ridged and sagging--not between the trusses but parallel with the eaves.
Any advice would be appreciated! Thanks!