On a 1950's cape in Oreland Pa (zone 4 but near 5)we are retrofitting attic insulation and doing a new roof. Generally, the proposed roof section of this cape will be metal shingles, 1" foam, original roof deck, dense-packed 2x8 rafter bays. Given the foam-on-roofdeck, it is intended to dry to the interior. Questions:
1) Does anyone have experience with metal shingles? We are looking to avoid asphalt and make the most sustainable decision given the budget. What is the best underlayment? What other roofing materials should we consider? We want to use a shingle manufacturer that will accept a hot roof assembly in terms of their warrantee.
2) With the build up of foam/plywood on the roof deck and no overhangs, what is best way to finish the now-large roof edges? What considerations at the valleys? Best type of foam? How thick for the plywood? Note: This is currently an unvented roof with no opportunity to ventilate because of no overhangs and the presence of dormers and valleys prohibiting adequate and balanced ventilation.
3) Should we use CCSF inside the kneewall attic spaces at the eaves to properly seal and insulate the bottom of the slope and down across top plates?
4) If we dense pack the roof rafter cavities where it is sheetrocked (from the top, since we are re-roofing), what is the best way to deal with the open bays between the kneewalls and eaves? In other words, how do we dense pack the open bays? should we clad the underside with rigid foam and then dense pack? Again, this is intended to dry to the interior, so while CCSF would be easier, it would create the dreaded sandwich, as might the rigid foam panels on the inside.
5) The actual attic above the 2nd fl. ceiling is only 4' across and 3' high, it is a 10 pitch slope. Should we fill it with cellulose? There is only 1 insulated flex duct serving as a return jumper in the attic and no HVAC equipment. There are gable end vents that we will seal up. There will be no chimney.
6) There is a history of ice-dams at one section of lower roof. I am hoping that we can remedy this by this treatment. Any thoughts?
7) What considerations if any with the following roof penetrations: 2 bathroom ventilators,1 vent stack; 2 copper antifreeze lines for solar-thermal; 1 wood stove chimney- B vent.