The more I learn about fiberglass, the less I like it.
1. Formaldehyde is in it. None in cellulose.
2. It looses 20% of its R-value @ 0 deg F, and cellulose doesn't
3. Blown in fiberglass is the worst, because the r value per inch varies greatly with density cellulose does not.
4 Blown in fiberglass doesn't settle, so the ONLY way to know the density is to measure it!!
5. Fiberglass has a lower R per inch than cellulose.
6. Fiberglass cost's more than cellulose.

Can you guys get Roxul bat insulation in the States? We can get it up here and I wish my entire house had it at least. It's fireproof, sound proof, it doesn't have fiberglass in it, it's made of material that you can touch with your hands because it's made of mineral wool and it's R value is slightly higher then fiberglass. The 2x4 bats are R14 instead of R12 and the 2x6 bats are R22 instead of R19.

www.roxul.com

I've heard this before. Does anyone who why this is, or have any info linking to studies done that prove this?

Convective Heat Loss in Loose-Fill Fiberglass Insulation
 

It took a little while to find, but here is some info:

"For example, ORNL researchers have determined that some types of blown-in insulation in buildings in the northern United States permit air movement within the insulation, resulting in natural convection. Compared with conduction, convection allows more heat to escape from within a building to the outside. The researchers confirmed that natural convective heat loss in some loosefill fiberglass insulations can be responsible for as much as half of the heat loss at very low temperatures."

ORNL Review Vol. 25, Nos. 3 and 4, 2002

http://www.ornl.gov/info/ornlreview/...t/usemain.html

I'm looking for the original data, but the study is old enough that it might not be online.

Tim

Hope this isn't considered necro-posting, but I had a couple of questions. Daox, you found a big price difference, but you did not specify which brand was cheaper. Also, I am wanting to do this in my attic, but I have a fireplace....how do I go about sealing around it, or keeping it seperated from the cellulose?

I ended up going with the comfort control cellulose. It was $4 per bag versus the $6.50 for greenfiber. The bags contained the same amount of cellulose. This worked for me mainly I think because the comfort control cellulose is manufactured pretty close to where I live. I'm sure the greenfiber is shipped from who knows where.

I'm not sure exactly what you need to do about having cellulose close to the chimney. I would look into using rockwool insulation close to it as that stuff can take massive amounts of heat. Then just blow the cellulose up against that. That would be a better alternative than creating some sort of metal dam around the chimney. Sealing is also very important, but I'm not sure what sealants are used for higher temperature applications such as a chimney. The chimney in my attic is not used anymore so I didn't have to worry about any of that.

Daox, if your chimney is not used then you might want to insulate around it and install a plug in the top of it otherwise you will have a cold draft down the center of it and this cold mass inside of your house, even insulating it inside of the attic should keep it warmer, but any sort of plug or cap on the top will help.

As for insulating around a chimney that is in service, there are fire stop foams that you can get to seal the gap, there are also high temp silicons out there, then you are supposed to have a set amount of non combustible around chimneys, 5/8" dry wall often will work for this, cement board, I think polyisocyanate foam with foil facing, fiber glass insulation, even tho with brick chimneys they often have floor joists resting on the brick, useing the chimney as a post, it's still a good idea to keep new flammable material away from it if it's easy.

I almost forgot! if you insulate in 2009 or 2010 keep your receipts for your income taxes! http://www.energystar.gov/index.cfm?...tax_credits#c2

Thats a good idea Ryland. I had thought about it, but didn't think it would be that big of a deal. The chimney is currently cut off in the attic. But, there is the exhaust pipe for the gas water heater going up it from the basement. It is mostly sealed on the bottom end, but totally open on the top. I'll definitely look into sealing that up with some polyiso and high temp silicon. Thanks.