plywood sheets need some guidance on types

happyhero

Hi I am building a shed and I am doing it from scratch so that I can build it to suit me ie I am building it much stronger than a shed I could have bought from a garden centre etc, so all the timbers are bigger than usual. I would like it to be much stronger than normal. I have looked in some books about shed building and in some of them they have clad the timber frame walls with ply sheets and then covered them with shiplap or loglap etc. Not sure if I will do this due to cost but if money was no object it does seem better/stronger/more weatherproof this way.

Anyway I am not too knowledgeable about the different plywood sheets you can get and I was thinking of making the floor out of these sheets. I always thought ply delaminated in wet weather yet you always see it used for shuttering round building sites and it seems to last ages even though the edges point right up at the rain coming down. Yes I know they paint them but even so. I have heard of things mentioned like Marine ply and WBP what ever that stands for etc but what would I want for a shed floor?

ie what thickness would be best (its going on 2x4inch timbers)?

what type would I need for outside (might get a bit wet during building until I have a roof etc)?

Is there anything to watch out for when buying?

Should I store it a certain way if it may get wet?

I would like a decent quality ply for the floor as I have seen some really rough faces on some but obviously for a shed I don't want to pay the earth. The shed I am building is 8' x 20'.

Any guidance/help appreciated.

ormus

http://www.glen-l.com/wood-plywood/okoume.html

a usa site but most of it applies here too. ive used marine ply to build boats.
if you want the best then marine ply is the answer. it aint cheap though.
exterior ply is next best if treated or painted regular.
if budget is really tight then oriented strand board is ok, again if painted regular. will last 10 yrs or more.