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.

 

[oilman]

If you dont want to pay the earth for the floor, use scaffold planks. 1-1/4" thick, 4m long will cost around £8 inc VAT each delivered new. You may be able to get s/h.

For sidings use OSB much cheaper than ply and if you are going to board over it, it'll be fine. 11mm will be ok for sides.

To prevent water damage, build the frames first, put the roof on, then work in the dry.

 

[big-all]

at 2ft centres go for 18mm ext ply for floors and roofs
at 16" centres go for 12mm ext ply for floors and roofs
ext ply will last for ages in wet and dry cycles as the glue is water proof

ext walls 12mm interior skin between 12 and 6mm ply dependant on weight hanging from it and battering force

i used 12mm shiplap on mine

 

[Thermo]

If you dont want to pay the earth for the floor, use scaffold planks. 1-1/4" thick, 4m long will cost around £8 inc VAT each delivered new. You may be able to get s/h.

For sidings use OSB much cheaper than ply and if you are going to board over it, it'll be fine. 11mm will be ok for sides.

To prevent water damage, build the frames first, put the roof on, then work in the dry.

you can pick up second hand planks from most scaffolders for about £1-£2 each. They are useless to them, and it normally goes to their tea fund. As oilman says decent wood for the price that will last years

 

[happyhero]

Cheers guys all very helpful but if you went to this site

http://www.allowaytimber.com/index1.html

one of my local timber merchants, which one would you buy, as they have marine ply, red/white WBP ply, shuttering ply and Wisa Spruce ply?

Not marine as I suspect unnecessary and too expensive but maybe a toss up between Red/white WBP and shuttering (quite cheap). I may be tempted with going to 18mm for strength. Will the shuttering one have a decent surface if I picked that?

Scaffold boards seem like they will be very expensive to cover the area I want compared to ply.

Very impressive workshop, gives me some ideas too.

 

[big-all]

sorry exterior = wbp

marine is overkill
shuttering poor quality poor finnish

sterlin board poor mans ply

all the above will put up with a few wet dry cycles no probs

spend your time planning the layout do one area at a time once finalized do another section to accomodate some other tools and boxes and keep working round till you have filled all areas

 

[masona]

I would like it to be much stronger than normal.

I've bought 2nd hand precast slabs (hairline cracks or slight damaged corner which won't be seen) then covered it with log cladding apart from the back as it's on the boundary line which you can as it's fireproof, I can't think of anything stronger than that

ps: my small shed is in the garden sticky

 

[Deluks]

Might not be worth using sheets on the outside. Just felt/batten then fix the cladding. Save the dough and line the inside with ply instead. Will be strong enough and you can insulate behind it and give it a coat of paint.

For the floor I'd get 5 sheets of t&g roofdeck osb.

Whatever you do though make the whole structure is raised up off the ground a few inches. Strategically placed paving slabs or bricks to support the floor joists every 18" or so.