expanding foam inside body cavities?

okay, ive been thinking about this for a while. what are the pros and cons to using expanding foam inside the body cavities? between the bedside skins, roof skins, inside pillars, ect? it helps deaded road noise, i know that. and helps keep stereo sounds in. and heat. but what are some disadvantages to doing it? is it heavier than products like dynamat? i want to somewhat lower the roadnoise, but not add tons of weight to it. id like to keep sound/heat insulation to under 50lbs. 100 max. thanks guys.

oh, and i believe the new f150s, gm trucks, and a few other things do stuff like this here and there, but not the whole vehicle.

I did it inside my trunklid once. It expanded and deformed the outside of the trunklid.

It will warp your body pannels, that stuff has alot of "power" when it's expanding.

expanding foam in your body cavity might hurt.

Edited: 11/7/2006 4:36:35 PM by BigJay43

If u try to fill a box with foam thats enclosed on all sides...box will get warped. But if one side is open I think the excess would pour out of the open spot i would image. buuut dont take my word on that cause yea ive seen it dent some panels before with open space.

u know what....i dont even know anymore.

but still even if the foam doesnt blow out your panels if you have any kind of leaks or condensation it will soak up alot of water and the unpainted inside panels will rot from the inside out right or wrong?

dont do it. It warped a trunk lid I had on my prelude a few years back.

i used it on my wagon once down into this crossmember that had no way to get into and there was some debris in the that would rattle. drilled a hole and filled it up no more rattle

also it can cause rust out due it could trap moisture inbetween it and the panel.

duramix makes some expanding foam like you would typically see in a car not at the home depot. its a 2 part epoxy based foam and its tits.