agermich

For a standard black stage floor on top of concrete I would be doing 2 layers of 18mm ply with the joints offset. This will give a good sturdy base layer with some thickness to screw into when required. I would then skin it with 6mm MDF or oil tempered hardboard as a top layer to paint black, which can easily be replaced if it gets damaged or worn over time. Don't do a permanent ply floor without a sacrificial MDF/hardboard layer as the top layers of the ply can wear through and start to de-laminate after a few years of heavy use and numerous coats of paint. I would suggest screwing the ply together and then pinning the 6mm on with brads or narrow crown staples. Mike