attic floor insulation options


Old 08-30-01, 09:13 PM
Able Sashweight
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I'm wondering about the appropriatness of cellulose for the attic floor of this 80 year old house with lath and plaster walls and ceilings. Eventually I may finish out the attic.that's 5 years away or more. Current insulation is a partial covering of rock wool; its compressed, full of rat turds, and is getting mangled as I pull out the old wiring. So what was ther was marginal, andwill be tossed.

I don't want rats to nest there. And they live in the neighborhood.
I don't want to get cancer or other sickness from breathing the stuff. breathing microscopic glass/mineral fibers sounds dangerous regardless of what the producers say.
I want good insulation that will stand up over time.
I'm not wealthy.

So about cellulose.

What do they put on it to make it fire retardant? A borate of some kind? what are the health risks of breathing it?
Are there any issues about having it scattered loose on the attic floor? roblems due to kicking it up as I occasionally walk through for house maintenance? Any problems related to a whole house fan?
Any vapor barrier concerns? the kraft paper on the old mineral wool rotted and crumbled - a lot of use it was. I figure my interior paint is my vapor barrier.

Or should i consider something else?

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Old 09-01-01, 07:26 AM
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Able, you have two time periods involved here, so, I will ansewer for both to save you money. I recently did a job with very similar requirements and the churh was very pleased with the results. It was an older house converted to small church.

To save time and money and at the same time get superior results install a Type two radiant barrier (RBI) between the joists and not touching the fiber material. The RBI material must be a perforated type. DO NOT install over the joists. The wood must breathe. The performance will exceed that of any bulk type insulation.

5 yrs later, when you are ready to finish out, install two layers of Type 2 RBI. One between the rafters and one over the rafter surface. Install 7/8" steel furring strips ACROSS the rafters, 24" c/c. The reason for this is that you have a excessive amount of heat conducted thru the rafters and by using this method you will eliminate most of it. If possible install a ridge vent and soffit vents.

All your concerns in your question are vaild. Since you probably have ballon framing be sure to seal off the tops of the walls with sheet metal both exterior and interior walls.

For Radiant barrier into, enter into your search engine..
"radiant barrier insulation" and "reflective insulation"

Thank you for consdidering my personal opinion regarding your project. If you need any further info ,such as, exterior walls, material source, etc., please let me know.


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