There is a foam used for cavity filling but I wouldn't recommend it.(It's actually intended for cavity walls in houses)
Problem being it also retains moisture i.e. condensation/damp.
This could be a major problem as I see you're from the frozen North!
I used it a few years back in a VW Bug I had and it was a nightmare,it caused some panel repairs I had done to bubble up with rust.
Basically it acted like a sponge.
Last edited by jockbolter50; 02/08/2010 1:21 AM.
