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-   -   OK to blow cellulose over blown fiberglass? (

Bubba Ray 12-13-2010 04:00 PM

OK to blow cellulose over blown fiberglass?
My access to 1/2 of my attic is thru a 1' by 2' hatch in a second story closet. The blown fiberglass is full of mice holes and acorns and is thin(2-4"). The freeloaders have been evicted. The area is open with no walk or crawling boards and the ceilings below are textured. I would like to blow in cellulose over the fiberglass. Any problems with this idea?

inspectorD 12-13-2010 04:17 PM

You just may get a lesser R- value in the long run.
If this was my job, I would remove all the nasty stuff with the insulation . If you ever need to do any future electrical or plumbing work this is going to make it a mess. And it will get rid of any smells that stay in the old fiberglass.
:) Just my 2 cents.

GBR 12-13-2010 08:51 PM

As ID said, remove the old and other solids, replace and check the weight with the existing drywall and on center spacing: Residential ENERGYSmart Library

Cover the attic side of knee walls with house wrap to prevent wind-washing and convective loops in the wall batts:

Stuff small plastic garbage bags with f.g. to air seal under (between joist bays) and over (between rafter bays) the knee wall- tight to the baffles at the sloped ceilings. Use foam electrical outlet covers to air seal the heat loss there.

Wear a mask, gloves, long sleeves and goggles around the mouse feces as it can cause major health problems.


Bubba Ray 12-22-2010 08:32 PM

Not going to remove old stuff.
No way will I remove the old stuff. Will install baffles for sofit vents and have ridge vent now. Just planning to blow cellulose on top of the fiberglass. The access to this area is terrible!

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