Stiffest plywood?

[tob_ekl]

Hello!

Which plywood is the stiffest? Form plywood or regular plywood?
I'm going to glue it together with a drywall sheet. I want the construction to be as stiff/strong as possible. Or is there another good option such as Pergo? It's going to cover a floor hole. Does regular wood glue adhere to form plywood?
Thanks for a quick response!

 

[Larsa]

Formplyfa is basically a construction plywood with plastic film on it, so there's not much of a difference. And the purpose of the plastic film is to prevent concrete from sticking, so glue doesn't work very well.
I don't know how big the hole is, but construction plywood isn't particularly shape-stable if we're talking about the 12mm variant. Maybe a thicker sheet or a plywood of better quality?

 

[Fredrik.engdahl]

there are construction plyfa in different thicknesses, but they cost about twice as much as a regular one

 

[tob_ekl]

I can't increase the dimension, 12mm applies. Of course, I want as reasonably good quality plywood as possible. Or some other board. It will have parquet over it, so I want as little flex as possible. The span is about 30cm.

 

[anaitis]

I cannot increase the dimension, 12mm is applicable. I want as reasonably good quality of the plywood as possible, of course. Or some other board. It will have parquet over it, so I want as little flex as possible. The span is about 30cm.

For such a small hole, 12 mm plywood is more than strong enough.

 

[styrman1]

Take a sheet with as many layers as possible. I believe there are up to 7 layers on 12mm snickeriplywood.