Cathedral/vaulted ceiling in mobile home-insulation
Hi, here is my first thread. Glad to find this website.
We have bought a mobile home as a second home in NY state, double-wide with an addition, house has built in 1983. On winter 2012, we had ice dams that caused an infiltration of water. So, we removed all the insulation, treated the wood with a machine that we rent at Home depot to control the mold. We have noticed that the insulation was very poor and there was not much vent in the soffite. We checked in the family room and in the dining room which there is a cathedral ceiling to see what kind of insulation was there, so we noticed that the trust there are only 8 inches that lets 7 and half inches of deep for insulation, minest the minimum air flow for the ventilation of 1 inch, we can put only 6 inches and half... of what could be the best combination to maximize the R-Value in that circumstances?
1-) using baffles, 5 inches and half of Roxul Batt with one inch of styrofoam. I don't know if I can mix batt and styrofoam?
2-) using only stryrofoam, 2-3-4 inches?
3-) something else? but we don't consider spray foam or to add space with 2 x2 or other; we want to keep the actual height of the ceiling.