On 3/21/2014 7:15 AM, Stormin Mormon wrote:
On 3/20/2014 8:59 PM, Oren wrote:
On Thu, 20 Mar 2014 17:18:49 -0700 (PDT), wrote:

Hi,
I've recently bought a 1930's house with a whole house fan that
discharges directly into my attic. The attic has gable vents, so
plenty of discharge space is available. The attic floor joists are
2x6's and the fiberglass insulation is ancient... it's matted down to
about 2" high. I'd like to replace the insulation. It's covered in
a heavy layer of dust, probably most of which was deposited over the
years by the whole house fan.

Is it ok to replace the fiberglass insulation and just let the dust
settle on it over time? I have little interest in spending money to
cover the attic floor with plywood or OSB just to keep the fiberglass
relatively dust free. Should I worry about this sort of thing?

All comments appreciated.
Regards,
Theodore

The insulation you have as lost some R value being compressed. I see
no reason that can't leave it in place a blow 6 inches of blown
cellulose insulation on top of it. IMO

What kind of cellulose action do you expect
when the OP turns on his whole house fan?


I don't know what Oren expects, but I would expect none. I have that
situation in my house and the blown in insulation does not move when the
fan is turned on.

My thought was similar to yours. So, before I bought the house I went
into the attic, closed the hatch and had them turn the fan on. The
attic pressurized immediately and the insulation didn't move. The
turbulence was all near the peak.