# Attic Insulation: 8" Cellulose vs. 5" Fiberglass?



## strategery (Jul 18, 2011)

I'm not a professional, just a homeowner.

Having said that, your quotes don't make sense to me. 5 inch of fg isn't going to give the same r-value as 8" of cellulose. Cellulose will settle some but it still will perform better than fg.


What climate are you in? You need to air seal your living space to your attic first air sealing helps manage convective energy loss. Insulation will help manage conductive energy loss.


Once your attic is properly sealed from the conditioned space, you might be able to keep your attic fan to facilitate with moisture migration (i.e. prevent condensation, frost, mold, ice damming). Most people seem to think passive attic ventilation (usually ridge & soffit vents) is the best.


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## fg12351 (Mar 21, 2012)

I am in Indianapolis, IN.

I have all new soffits on the house.

I agree, the quotes are confusing. I think more would be better in this case but I agree I should check for air leaks.


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## Windows on Wash (Aug 30, 2011)

Both have roughly the same R-Value per inch.

That being said, the cellulose is the better insulator in every capacity.

Just get a premium blown in cellulose that is borate only stabilized.


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## jklingel (Dec 21, 2008)

to add an explanation, fg batts are poor for attics (especially. they are not great ANYWHERE. OK, but not great) because any air currents will pass through them and carry away the btu's (but leave behind the bugs and rodents that like fg).


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## Nealtw (Jun 22, 2017)

Morrisville_Insulation said:


> As I shared in another post, there is a form of blown insulation that is 100% green and made from Milo (which is a plant). It works amazing, and also has the added benefit of staving off critters (as a natural repellent). Just some thoughts.
> 
> -Michael
> Morrisville Insulation
> ...


This thread is a little old.


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