In message , Andy Burns
writes
DerbyBorn wrote:

Our current floor is tongue and groove but with significant gaps and the
boards are slightly convex.

Punch the nails below the surface then use a small block plane to
flatten the raised portions of the boards, I did this when fitting oak
flooring over floorboards (also replaced a couple of boards that
someone had lifted/butchered).

Our builders simply stapled thin ply over the 9" floor boards here. 26
years ago so perhaps 0.25" prolly 5.5mm now. I didn't notice them doing
any serious preparation work.


--
Tim Lamb