Attic Insulation project

It's PINK only because the manufacturer, Owens-Corning, wanted to differentiate their stuff. The pink color is actually part of their trademark. In other words, it's not the color that makes the difference.

Your R-38 is overkill for Orange County. In San Diego County, about 15 miles from the ocean, we have 6" of fiberglass insulation, and this is a custom house. That's about par for houses in this area. Certainly is all the insulation we need.

Check with other homeowners in your area. You probably waste your money on anything over 19.

"Carlos" wrote on 23 Aug 2006:

You're missing a fundamental point about batt insulation. Batts fit between the joists, so if the batts are higher than the joists, you'll have gaps between the batts the width of a joist that will be uninsulated. What you want to do, if you're using batts, is put just enough down as a first layer to get to the top of the joists (R-12 if they're 2x4s and R-19 if they're 2x6s), and then put a second layer (without the kraft paper facing) perpendicular to the joists on top of the first layer of batts. The second layer should have a thickness of whatever it takes to get to the R-value you want. Generally, one inch of batt is R-3.

So unless you have 12" tall joists, R-38 batts would be a total waste unless you want to squander your time cutting 2" wide strips of insulation to fit between them.

I also think R-38 is overkill for the Orange County climate, but insulation is cheap. For a given R-value, as another poster said, the color and manufacturer make no difference at all unless there's a special feature you want (foil-faced or non-contact with the fibers).

Thanks for the advices. The joist are 2x6, so I will use a lower krafted R value to fit it just to the level of the joist, and then put another layer on top. I guess I was vague when saying Orange County, I live in La Habra, which is fairly inland and in the summer it gets between 95 to 100.

Doug Boulter wrote:

First install the foam or cardboard "chimneys" to the roof side to allow for ventilation. Place batts between the rafters with the paper side toward the living space. Then put unfaced rolls cross-wise to the batts. Brands are not that important.

Doug,

I realized that there won't be a gap if I use R-30, which they come in batts of 10 1/4inch by 16 inches, since the space between the joist is only 14 1/4 inches (roughly), so that means that whatever 'sticks out' will puff out so it will push right next to the batt right next to it.

Carlos

Doug Boulter wrote:

"Carlos" wrote on 02 Sep 2006:

Carlos,

I'm not sure you're going to be happy with that because the batts won't go together tightly above the joists.

I'd still overlay a second set of batts across the first set of batts, but you can use unfaced R-9 to do that.

But it's your call.