Screw - plywood to plywood

[orkaorca]

I will screw plywood to plywood, both 15mm. It must be strong. It is a narrower piece of plywood about 7cm that will be attached to a plywood sheet serving as a wall. Ytong behind the plywood sheet. I will use PL400 but which screw should I use to attach 15mm plywood to 15mm plywood?

 

[Matti_75]

28mm plywood screw

 

[justusandersson]

I would use a regular 30 mm wood screw with a large, countersunk head (designation TFT) and pre-drill through the first plywood. Sheet screws of various types are intended for fastening sheets to steel or wood studs. I think they have too steep a pitch for fastening in plywood.

 

[prototypen]

I have a preference for gipsskruv.
It's probably not so much a question of what kind of screw but more about how closely you screw.
Drilling through the first plywood sheet is a requirement.

Protte

 

[orkaorca]

I have a fondness for drywall screws. It's probably not so much a question of what type of screw, but more about how closely you screw them. Drilling through the first plywood board is a must.

Protte

how should it be pre-drilled? 1mm less than the screw?

 

[prototypen]

In the board you place, the one that is 7 cm wide, you drill a hole so the screw is free; for a 4 mm screw, you drill 4-4.5 mm. If you use a normal, modern screw, no drilling is needed in board 2.

Protte