My pine floor is 22mm T&G attached to steel beams with Wurth Zebra
Pias screws. Pilot hole in board and self tap into 6mm steel with
ease - up to 10mm with care!! There is a foam/foil insulation layer
under the pine. Getting boards T&G would probably be expensive - I
would be tempted just to put in some biscuit joints at say 300mm
intervals.

http://www.luxe-motor-kei.co.uk/inte...e/image35.html
http://www.luxe-motor-kei.co.uk/inte...e/image37.html