Whole house fan with attic insulation
Hello,
I have a 1950’s ranch that has a whole house fan in the ceiling of the hallway and it also has a large, jalousied gable vent window in the attic. The large (at least 2’x2′) vent window often lets rain in and I’d like to get rid of it. My attic is also not air-sealed and has a sporadic layer of 4″ thick fibreglass batts as insulation.
So I’d like to air-seal the attic and then add a nice thick layer of cellulose insluation in the attic.
Can I still have the whole house fan with only a ridge and soffit vents or is that not enough? Also, I know the whole house fan will be the weak spot in my attic insulation in that I will have to build a box around it to keep the insulation in place…in cold and really hot weather can I just make a thick plug of rigid insulation to cover the whole house fan box? Or is there a better way?
My wife really likes the whole house fan in the spring and fall but I know we’re losing LOTS of money through our attic in the summer and winter. Insights or recommendations appreciated! Thanks, George
Replies
We have a whole-house fan here in southern Minnesota (where we also obviously have insulation, about 18 inches of blown in cellulose).
Before the new cellulose was blown in (originally had about 8 inches) I built a box around the fan. One could use lightweight plywood, I suppose, but I used old corrugated plastic campaign lawn signs. This keeps the cells out of the fan. Then, in the late fall, I place a "boxtop" cover made of the same plastic over the top of the fan.
(In the spring the cover blows off the first time we use the fan, and then, when I get a chance, I crawl up there to move it completely out of the way.)
Also used the old lawn signs as a part of the chutes I built to keep the soffit vents clear.
This has worked well for over ten years.