Insulating sloped ceiling in old house
We are reinsulating the attic of our 100 year old home but are dealing with a difficulty. The top floor has a sloped ceiling from about five feet high to the flat ceiling. When we bought the house, the previous owner had stuffed this from the attic area with batt, which had blocked the soffits and caused premature aging of the roof. We unblocked the soffits, reroofed and added a ridge vent. We are now in the process of replacing the wood shavings and need to be able to insulate this area. We were planning to do spray foam but have been told they would need to rip out the dry wall of all the sloped areas (four bedrooms, three closets and a bathroom!) in order to do it properly. The problem with this (aside from the obvious increased work and cost) is that the drywall is over plaster which has been a misery to deal with in other parts of our renovation. We need a solution we can install from the attic area that includes a vapor barrier and the best degree of insulation we can achieve. We have been advised to install baffles from the soffits and expect this to cause some space issues though hoping we can somehow insulate around either with blow-in, batt or insulation board? We have been advised to use a paint on the ceiling of the top floor to provide a vapor barrier as this area is so inaccessible. Does this make sense? Should we ditch the idea of spray foaming anywhere and just go with batt, blow in or cellulose? We live in Calgary so have very cold periods in the winter so are looking for our best option. The house walls were wrapped from the outside at some point with insulation board I believe. Thanks for any advice!