I have a walkout basement situated on a cement slab. I am wanting to make a screened in porch around this (18’ x 12’) and there are footings at each corner with a slab in the center. I’m wondering if or how to build a framework that might resist heaving because of cold temperatures. 
 I’ve been told that you can use some type of a foam sill plate that would rise and fall with the temperature change. Do you have any suggestions on the proper way to do this to compensate for heave?