What length screw for ply board over pine floorboards?

[Mutley56]

Hi there,

I have over boarded a suspended timber floor in utility room. Floorboards are 18mm thick and the ply board is 5.5mm thick. What length screws should I use to secure the ply to the floorboards? I am going to put them in every 6”.

thanks in advance for replies.

Mutley 56

 

[big-all]

your choices are 3/4"[19mm] 20mm 25mm or inch [25.4]
if its say 18/19mm flooring then 3/4 20mm sunk 2mm
if its say 20/21then 25/1" flush

 

[Deleted member 174758]

18 to 20mm should do the trick.

 

[Mutley56]

Thanks for the advice. I have some 20mm screws but not enough. Off the B&Q to queue up outside in the rain.
Thanks again

Mutley56