In article . com,
says...
- I was
thinking of drilling holes in the drywall on main floor and spraying in
the foam in a can made for doors/windows so as not to expand the
drywall. Is it worth adding this 1" of insulation as the exterior wall
is currently estimated as only r4? I read some articles that said that
first inch gives a great reduction in energy and then falling return -
I would do it myself over a period of time so labour is free and as
only 1" gap not going to take much foam.


You don't want to try it with Great Stuff. Tiger Foam makes a cavity fill foam
in do-it-yourself kits:

http://www.tigerfoam.com/products.php?cat_id=1

You can also fill the block with perlite, although you have to be able to get
at the top of the blocks to do it, so that is probably a problem.

--
Dennis