I'm in Santa Monica California and have a walled outdoor patio area adjacent to my house that I'm going to put a patio cover over. It will have open sides with curtains to retain warmth from a ventless fireplace. It gets chilly here at night even in the summer so I'd like to help the situation with radiant heat in the slab... even if only for foot warmth.
I have to pour a new slab anyway and will put a electric heating mat in the top two inches of the new concrete. Before the pour, I'm going to lay a vapor barrier and insulate the bottom and sides with foam boards or a product like Insul-Tarp. The intent is to not heat the ground or let the heat escape out the sides... just radiate upwards.
BUT...this slab will still get partially rained on and will be often hosed off. Are these moisture barriers a problem in my case since I need the slab to often dry and not channel water under it to the surrounding structures. I was going to use one of these under it. http://www.eagle-mt.com/radiantmax/Insul-Tarp.php
The 12x50 roll.
I'm confused as to whether all the instructions online on how to insulate slabs refer only to those that are not routinely exposed to water. Any advice... thoughts?