Wood – What’s the minimum subfloor thickness required for hardwood flooring

If it's not visible, just got for a manufactured board, e.g. plywood, OSB, etc. For 3cm, you may be looking at two pieces stacked on top of each other. If it's on concrete, install a moisture barrier first. To secure the boards, I'd avoid the temptation to use a Ramset and permanently drive the names into the cement, since the next time the flooring is redone, you can take the opportunity to do it right and pull everything up and go wall to wall. Instead, secure it with a few cut nails. Again, this all assumes that none of this is visible.

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I have placed Dricore or its equivalent on 2 different jobs. Both are holding up fine, neither felt hollow or creaky. One was in a basement slab, the other was placed on a slab on grade such as yours. The only difference is one had 4" to 10" wide plank flooring from recovered barn wood, the other 2 1/4" strip.

While the subfloor was being laid, I glued the edges of all the pieces before placing. even though it is not required. Also the perimeter had a gap to the wall of at least 1/2". It is laid as a floating floor. I really don't see any problem stapling down your engineered floor to that. When the strip floor went down, the staples where checked for length so they did not go all the way through and pierce the plastic matting.