Originally Posted by asalcedo

36mm for the top plywood board (two 18mm panels)
28mm for a suplement on top of the joist to level it out
36mm into the joist (the same as the nails fixing the floorboards penetrated into the joists).

That adds up to 100mm

I was thinking of 120mm because the first 36mm into the joists has already many holes and the screws may not grab as well.

The joist is about 230mm tall and is certainly not pine, it is harder and redder.

Does it make sense?

If so, should I drill the pilot down to the full depth?

Thanks,

Antonio