Neptune Coatings is a West Coast manufacturer of some of the industry's premier industrial coatings. We subscribe strongly to two:
First, is WetSuit® liquid membrane - a fully self-adhered, cold spray applied, self-flashing membrane with a wide variety of uses for virtually all above and below grade applications. Sticks to concrete (and virtually any material) so as to form an unbreakable disruptive layer that won't break down or degrade; acting as a barrier for water, gas and any un-wanted substance. We primarily like Wetsuit as a barrier against gases; methane in particular. There is a familiar building zone from the east side of Downtown Los Angeles all the way down the Wilshire corridor to the Pacific. This material has an LARR #26190 that says the same.
This material can be applied horizontally and vertically to form a complete, seamless enclosure system; on protection board across your foundation (mat/raft slab) and up temporary shoring (walls). It's physical properties can bridge cracks and the soil movement constraints of the Southern California project conditions. Depending on site particulars, you can usually budget this material in the $10 a square foot, installed, range.