Air sealing and insulating finished attic space
Hi. I’m new here and would like to start by thanking everyone who shares their extensive knowledge with homeowners like me. I read last year’s thread on retrofitting insulation to a 3rd story finished attic with great interest as I have the exact same problem. However, I didn’t understand some of the technical aspects and a definitive solution was never determined. The link to that thread is
We live in an old stone/stucco (100 years) house outside of Philadelphia. The third floor is essentially a finished attic space with three rooms and a bath. There are 5 large dormers and several large closets built around the kneewalls. I have no reason to believe that the dormer walls, kneewalls or sloped ceilings in the finished areas are insulated. The attic floor above the finished space has loose cellulose between the rafters, installed around 10 years ago. There is also an airhandler and flexible a/c ductwork in the attic. Like the previous poster, we too have limited access to the space behind the sloped ceiling, dormer walls and kneewalls. The proposal I received was to seal all leaks, ducts and registers then bury the ductwork in more cellulose which would also be dense packed into the slopes and kneewalls. I have no idea how the roof is vented but adding to the complexity is an 18″ stone wall that goes through the middle (sort of) of the house right up to the roof. My guess is that the roof it has a ridge vent.
I would like to insulate with spray foam but I know my husband would never agree to remove the existing plaster/lathe walls and ceilings in order to apply it everywhere. Would it be feasible to sprayfoam the underside of the attic roof and insulate the ceiling slopes, dormers and knee walls with either fiberglass or cellulose? If not, what would be the best way to insulate the whole space. The roof is only 8 years old (I wish I knew then what I know now. We could have avoided this mess). I’m really concerned about all of the energy we’re wasting and possible damage from ice dams (though the winters have been getting milder). Thanks for any advice you can offer.
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