Hi all, this is my first post, but I've been reading the forums for a long while. Canuck, I'm especially hoping that you'll be willing to weigh in here.
I live in a very cold upper midwest climate. Our 82 year old house is balloon framed. I believe it has fire stops, but I'm not sure. At any rate, the stud bays do not open into the basement. But the second floor stud bays *DO* open directly into the attic.
An energy audit has shown tremendous heat loss into the walls. And with at least the second floor walls opening into the attic, my guess is that the stack effect in our house is quite significant. (Our inability to keep the place warm without constantly keeping the furnace on suggests the same.)
I would like to curb this stack effect, and from what I've read the places to start are insulating the rim joists in the basement and the insulation in the attic. I'm going to tackle the basement soon. My main question is about the upper part of the house.
Currently there is very old blown fiberglass under the attic floor. Then, on top of the floor, there is a good 6 inches or so of fiberglass that was blown in August 2009 after the previous owners rewired the whole house as a condition of our offer to purchase.
My current thinking has me leaning toward the following: remove new fiberglass; take up attic floor; remove old fiberglass; have rock wool blown into the second floor stud bays that open into the attic; cap stud bays with foam; foam other air chases into the attic; roll out either fiberglass or rock wool batts and cover with old attic flooring; roll more batting on top of floor to achieve further R-value.
I have two questions: (1) is there anything about this game plan that invites moisture to be trapped in either the rock wool wall insulation in second floor wall or else the empty first floor walls? (2) if the answer to (1) is "No," is there another flaw with this plan that I'm not seeing? For example, will I have simply traded a basement-to-attic stack effect with a basement-to-tops-of-first-floor-walls stack effect?
Perhaps it's obvious by now that I don't have a clue what I'm talking about. Any and all help thinking all this through will be greatly, greatly appreciated.