I was at a recent project where floor gymnasiums failed. The inspector, based on his CACL tests claimed the moisture was coming from underneath..which I deemed close to impossible. In my assessment of the project, it was apparent to me that there was no significant source of moisture coming from the concrete itself (since the concrete slab was new, 8 inches thick, with a water-cement ratio of 0.45 - EXCELLENT concrete...kudos to the specifier and general contractor on that project!) Another inspection/testing company came in, who independently came to basically the same conclusions I did and upon further inspection, moisture became trapped between the waterproofed concrete surface and the impermeable flooring material through perimeter influences and improperly designed basketball, volleyball stanchions. There were a couple things wrong with the stanchions, one, theye were in direct contact with the concrete...which metal should NEVER be!!!! Metal can be 100 times more conductive than concrete, creating a gradient that can allow moisture to draw and/or collect in that area, two, the stancions were aluminum, which in direct contact with the concrete, creates an adverse chemical reaction and three the stancions were set all the way through the concrete, so when moisture would collect during the rainy periods, moisture would collect and rise up along side the stanchions and eventually spread out throughout any accessible areas between the floor and waterproofing. These conditions were in part, created by a 'wet lay-in' which has become an unfortunate trend in flooring installations.

If you cut your ply into 4x4 panels and cut 3/8" kerfs in the backside, you can rely mostly on the adhesive to do the holding. I prefer to glue and nail plywood to concrete and use 1&1/2" fluted masonry nails hand driven with a 2lb. sledge hammer. 1000 sq.ft. of ply is alot of work. In this case, the areosmith or similar makes sense. I've used powder activated (Hilti)and don't care for them.

Owen's PLANKFLOOR?