I have a new england log house w/ dormer. No attic. The dormer apprx. 10′ x 33′ . The way the roof is done now is 2” tounge & groove decking then 2” iso board, then felt, then shingle. 2” is all the insulation room I have to work with. No vents now exsist. The shingles are frying and leaking. What would you recommend would be the best way to replace this area to maximize the longevity of the shingles. Iso board will have to replaced too, it is wet. The pitch is 3-12. Thanks T