How thick should concrete be poured over INSTA-PANELS®?
The OBC dictates 4″ of 25MPA concrete for a basement slab. Many people try to make slabs thinner so they gain head room as well as reduce the amount of money they spend on concrete; however, pours that are less than four inches tend to crack more readily. Pouring over INSTA-PANELS® is no different than pouring over gravel as far as strength goes, providing all else is equal. A four-inch pour is always best.