stryped fired this volley in news:5f4df7ad-861e-
:

I can use r13
or r-19. I

How are you going to stuff R-19 into a 3-1/2" wall cavity? If you
compress it, it loses R-value.

Unless you go with spray-foam, you're not going to get more than about R-
13 in a standard stud wall. Also, it might be a bitch finding it in 22-
1/2" widths, since standard construction is on 16" centers, and R-13 is
almost never used as attic insulation.

LLoyd