I was in perth last week and saw how they install 12mm overlay direct to concrete.
I must say that the process was surprisingly easy.
They use Selleys VBS rolled onto the slab for the moisture membrane in the evening of the day before. The next morning they arrive and start laying the floor using Selleys direct stick adhesive. They use a 5mmx6mm notched trowel with the notches at 25mm centres.
They spread 400mm of glue and install 5 runs of boards. they them drill a 6mm hole in the slab and pin a timber wedge to the floor. they then use another wedge to push against the first wedge and the floor. this pushes the boards together. they then pin the boards randomly with 3mmx25mm concrete nails.
This sounds comfusing. But when you see it, it is really easy.
They rekon that the plywood install used here in the east is 10 years behind the process used in the west.
In Brisbane, call Northern Suburbs Timber Flooring at Brendale.