Heathcliff wrote:

Agree, the R13 stuff is 3.5 inches thick and is designed for this
application. It is the stuff to use for 2X4 framed walls. Get the
kraft-faced kind and install it with the kraft paper on the inside.
You unfold the little folded over strips of paper on each side and
staple them to the stud. When you're done the wall looks like a
continuous sea of brown kraft paper. Wear a dust mask while
installing the insulation; when you see the layer of pink fuzz
covering the mask at the end of the day, you'll be glad you did. Wear
old clothes and at the end of the day, just throw them away. They
will be scratchy ever after. -- H

Hint: Take a pair of old tube socks. Cut two finger-holes in the toes. Slip
over your hands and forearms.

Discard when the project's done.