Hi Jim, We put in such a floor in our house. A retrofit is tricky as we couldn't add much height to the floor because of the existing doors and window. In the end we designed a sprung wooden floor that is added just over 1 inch. The basic design was heavy neoprene pads 2"x 2"1/4" about 1 foot centers glued to the concrete. On top sheets of 4 x 8 marine ply (3/8'') supported by them running diagonally. Tongue and groove hard wood glued to this on top. So the whole floor floats and is not connected to the walls, edging covers the small gap. We used natural oil and wax finish. It's nice to dance on, and is easy on the feet. Have a look at the pictures here. I'm happy to give you more details. https://picasaweb.google.com/billandliz.baritompa/MakingSprungFloor?authuse… Dancing at our house: http://youtu.be/Cmy45YlDrUY You could also take a trip here to try it out first :-) . Maybe the down under version of Square English Contra? Cheers, Bill