Difference between structural and non-structural ply, help please

happyhero

Hi I want to lay 12mm plywood sheets in my lounge to cover my roughish floorboards before laying insulation sheet and an engineered oak floor.


The reason I am going to so much trouble is we live in a drafty 1930’s house that I am slowly insulating as I do each room and want a bit of overkill. The ply will help give me and extra layer that I can butt right up to the corners under the skirting and it will be a great layer to lay my new floor on. And the cost of it is not prohibitively expensive either. I have also insulated under the floorboards.


There is no turning back now as I have made the floor standing rad pipes the right length to include the 12mm ply.


The thing is I keep seeing structural or non-structural ply but cannot find a clear answer to what the difference is and so don’t know if I should bother with the more expensive structural ply.


What’s the difference in their construction?


I have young kids so I am wondering about liquid spills etc, getting through.


I have bought some ply in the past and it delaminated which makes it like crap so I definitely don’t want that happening again. That was before I even used it. Is the delaminating less likely with structural?


Any info/links/advice appreciated

firefox1956

Sounds to me like a bit of overkill here.
12mm ply is way too thick for what you are doing.
You want marine ply or exterior grade ply........
You used to be able to buy interior grade ply if that came into contact with moisture it would delaminate.
HTH

rosie383

We are planning exactly the same and were advised by our builder to use marine ply.

Davesnave

I agree with the above. Some of the standard ply supplied these days is carp.

tacpot12

Structural plywood is designed to be a consistent product, for use where strength and reliability is important. You would use structural plywood where it was the source of strength in the floor, e.g if you were laying it instead of floorboards or as the covering for a flat roof that could be stood on.

For over boarding, you don't need a structural plywood, any exterior grade wbp plywood will do. Definitely worth using exterior grade wbp, in case it gets wet at any point in the future.

phil24_7

What about OSB board?