You only need it to stay in place. Small globs every 12" or so should be enough. Get the correct adhesive. The wrong ones will just dissolve the foam.
Ron

 

You only need it to stay in place. Small globs every 12" or so should be enough. Get the correct adhesive. The wrong ones will just dissolve the foam.
Ron

Already got a type that says Foam board to concrete as an acceptable application

 

Liquid Nail Heavy Duty works and won't disolve the foam. Any PL product (other than the foam board stuff) will melt the foam.

 

Liquid Nail Heavy Duty works and won't disolve the foam. Any PL product (other than the foam board stuff) will melt the foam.

The PL adheasive I got is tan and it says "any foamboard product" on the list of applications