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I'm working in a 3 story apartment complex with multiple buildings. They used the blue foam board under the slab. The problem I'm having is the foam pieces that were around the slab are allowing the flooring to sink and crack. It's 4inch x 4inch strips of foam board to fill the space...
I am seeking advise on what product to use to fill at least a 4 inch gap all the way around the parameter of a concrete floor. It had foam blocks in it but the foam is causing problems with flooring and the gap under is causing moisture issues.