On 2005-11-27, Greg wrote:

I'm thinking of taking on the repair of the wall myself. It's about 6
feet in length but only about a foot in height, between the floor and
the windowsill.

FYI, when you replace this window, it may require safety glass. "Code
Check Building" says that safety glass is required if all of the
following are true: the window is greater than 9 square feet, the
bottom edge is less than 18" above floor, the top edge is greater than
36" above floor, and the window is within 36" horizontally of a
walking surface.

I was wondering about using low-expanding urethane spray foam
insulation in cans to insulate the 4 approx. 18"x12"x4" bays under
the window. [. . .] Since the wallboard is off, I'm thinking I can
shoot the stuff in, let it expand and cure, and if it expands out
too much, just trim it with a saw to be flush with the studs.

I recently did exactly this for a small area of my house. It is
feasible, just be sure it is economical for you. Your volume is about
21 board feet, so you'd need 2-3 24 oz cans of "Great Stuff", assuming
that is what you are using. I used a gun-applied product made by
Toldol.

These one part polyurethane foams are moisture cured, so for thick
applications, the proper procedure is to spritz a little water into
the cavity, apply a layer 1" thick, spritz a little more water, and so
on. I found this to be a bit of a pain, it was hard to get an even
layer with a dispenser designed for laying out beads of material. I
also found that the material continued to expand for up to 30 minutes
after applying it, so I waited between each layer.

Best of luck. I like the foam insulation, but I'm going to switch to
a two part product for wall cavities. It should go faster and be
easier, although I understand it is trickier. I'll have it
professionally sprayed if scheduling permits.

Cheers, Wayne