kirkclean

We are building a house and are ready to insulate. Our friend who is a contractor will have a whole lot of r-30 they will be removing from a commercial building that we can have for free. We live in the valley in N.CA and it does get hot, but not very cold. These are my questions:
1. We need r-38 in the ceiling. We have a large attic that will stay unconditioned for now and need to insulate below this area. We have 12" trusses with with the entire floor of the attic sheeted. Can I double up the r-30 even though it will squish it and leave now space for a flow above the insulation?
2. We have 2x6 walls. Can we squish the r-30 into the walls?
Thanks for any help at all.
Kirk.

nealtw

I am surprised you haven't had the experts all over this yet. You never want to stuff fiberglass into a space to small. if you talking about fiberglass you can split it easyly.
I would try to leave a little space under the floor and when you finnish the attic you do walls and ceiling and it won't matter.
Now the experts will come and tell that i am wrong.

oldognewtrick

Neal is correct, you never want to compress fiberglass insulation. Stuffing more insulation into a space will lower it's "R" value. If you have the insulation removed, weather seal the outside by caulking any area that will allow air intrusion into the house envelope from the wall or attic. Seal where any wires travel up through the top of the wall plates, water lines exit an outside wall, missing caulk around window and doors. Any place that will allow air movement. More insulation in this case will not be a benefit and in effect lower the "R" value in the wall.