Looking for some advice from those familiar with old homes and attic ventilation. Gonna be a long post, so you might wanna grab a beverage of your choice first.... My wife and I bought an old farm house a few years back, blissfully ignorant of many things (specifically, not realizing that having TWO oil tanks in the basement, with another buried outside, is NOT a good sign) Anyway, its a circa 1880 Foursquare Italianite, with two separate additions tacked on to the back of it. Im looking for input on the main part (the square) of the house. The house was vacant (but maintained) for a few years before we bought it. During that time a microburst storm hit the area, and the hail destroyed what had been a nice slate roof. The guy that owned the house put a new asphalt shingle roof on, but has not added any venting. During our home inspection, we found a bat colony in the attic, so the entire attic was vacuumed out, along with what was there for rockwool insulation, and about 6" of cellulose was blown in there once the bats were moved out. Im now in the process of working on renovating one of the upstairs rooms that originally had a plaster ceiling. Due to leaks/bats/whatever, much of the ceiling is in poor shape. My thought was to pull down the plaster, leave the lath, and put up new T&G. Here is where my brain started working, and where I need some input. I realized that the attic wasnt vented previously (other than two 4x4 holes in the soffit) because of the slate roof, and gaps in the boards. Its a hip roof with a flat portion on the top, so no real good access to put in a ridge vent, and no gable to add a vent there. So Im now at a crossroads as to how to proceed with my ceiling plan. I can either: 1. Spray foam the roof deck/rafters in the attic. This moves my envelope to the roof deck, and makes it so that I dont have to do anything else up there. I know this will probably be expensive, and I worry since its a "new" building product compared to others that have been around. I worry about trapping moisture if there is a roof leak, and if someone will curse my name when they go to work on the roof years from now. 2. Start a LOT of projects at once. Add a continuous soffit vent and static vents to the roof, or something like a solar attic fan, and blow more cellulose into the attic. The issue is that I dont have an effective air seal, so I would have to add rigid foam board with taped seams underneath the T&G panels. This should provide an air seal, and additional R value. The benefit is that a cold roof is a proven system, and nothing will be permanently done to the structure. The down side is that its a lot of work to get rolling, and I would want to get the venting in place before I work any more on my ceiling. Sorry for the crazy long post and lots of random information, but Im just looking for some help/insight on this issue. It seems like everything I read doesnt fit my unique situation.... Thank you in advance!