Is there a 'rule' for screwing ply down into floorboards? Am getting 18mm and 12mm ply to screw into floorboards. Am thinking 6' intervals along the edges but do I have to screw through the middle as well? Or will edges be enough? Also is 12mm ply thick enough to level wonky floorboards? Floors are different heights hence 18+12 mm to try and even this out 6mm fibreboard will go on top of all this before laminate
Cheers!
Cheers!