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Too much insulation??


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The research on attic insulation shows a declining rate of return after R Values of R-50 (16" of cellulose)have been obtained. This is about the maximum level of insulation I see. After this level is obtained, the cost of insulation and labor to install the insulation will exceed the savings in energy costs over the life cycle of the house. As long as the insulation doesn't block vents there should be no problem caused by additional insulation.

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Like Brian, I think that weight is the biggest factor here. Cells is heavy. Hope they've using better than 1/2 drywall there.

I think that anything beyond R40 in cells is wasted money, because I've heard that beyond that you get diminishing return on the thickness due to convective looping. That said, a few years ago I did a double-walled house designed by an HVAC engineer that had blown-in fiberglass wall insulation a foot thick and attic insulation that was about 48inches deep. He was so finicky about the insulation that he built a complete catwalk system through the attic so that nobody would ever have to walk on it or wade through it.



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Recently inspected a property with a one year old detached garage. Pegboard over cellulose insulation. But one heck of a musty smell. The property had excellent drainage and no plumbing. No evidence of any water entry. I have not had the opportunity to "fondle" any of the product. Was the smell from the insulation?

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Are you saying that he installed cells behind pegboard in the detached garage?

Cells isn't generally musty smelling unless it gets wet. The borate the cells is treated with is kind of neutral - like being in a warehouse full of salt - but it stinks to high heaven when it gets wet, stays that way for a while and molders. Also, rats and mice love to tunnel into the stuff and live in it and those incontinent little bastards will saturate it.

OT - OF!!!


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