I hope it doesn't. I just sent my kid to Walmart for a can of "great stuff". I wrapped the edges with masking taped and sprayed it in. It's drying now. So far, so good.

I'll post a pic of the result. Looks like I just wasted the whole can on the job, though. It looks like the valve will be clogged when done.

If it eats the foam then I'll take have to resort to "plan B".