18mm Ply - will this work for me?

[forestboy]

Hello

We are building storage/workshop affair in a forest, 12' x 30'. It's pretty wet up there.

I'm working out my design and want to use 18mm T&G exterior ply for the base. The joists are going to be 16" OC 2x6, on 2x6 sills. The plywood is going on top of the joists.

BUT - I can't find any large sheets of T&G ext ply anywhere, all I can find is the same, but in chipboard (not good), or non T&G plywood.


If I use the non T&G stuff, and fix the short ends over a joist each time or will my floor move about ?

Thanks.

 

[squowse]

Hello

We are building storage/workshop affair in a forest, 12' x 30'. It's pretty wet up there.

I'm working out my design and want to use 18mm T&G exterior ply for the base. The joists are going to be 16" OC 2x6, on 2x6 sills. The plywood is going on top of the joists.

BUT - I can't find any large sheets of T&G ext ply anywhere, all I can find is the same, but in chipboard (not good), or non T&G plywood.


If I use the non T&G stuff, and fix the short ends over a joist each time or will my floor move about ?

Thanks.

never heard of T&G ply. if you use full sheets of ply then you should have no problems, in fact as long as the pieces bear on 4 joists then no problem. i probably wouldn't go for less than 600 wide either. if you want to avoid small movements between adjacent sheets then fix the edges on noggins between the joists. are 16" OC joists I-beams with a sterlingboard web and timbers top and bottom?

 

[Jasonb]

I often use 22mm flooring ply, you can also get it in 18mm. I get mine here (bottom of page) but there are other suppliers try WT Edens they have a few depots around the country Look for "sprucefloor", its WBP bonded so OK in moist conditions.

Jason

 

[forestboy]

Thanks for the replies,

sq - this is the theme for the design :

http://www.popularmechanics.com/home_journal/home_improvement/1276536.html?page=1

I'm not sure what you mean by I beams and web design.

Jason, that's the stuff I'm after, but even local mills and timber suppliers say they can't get any, wickes etc, nothing at all.

If I can use the non T&G material and get away with it that would be OK, but I wanted an air/moisture tight seal.

You can't make on omlette without breaking eggs, but I'm building this at the end of a 45 degree forest track deep in some scottish woods! so everything meeds to be carried in by hand, a portable generator will be used for power and it's a hard place to work, so while noggins are a good idea, they would add a lot of time to the project which I can ill afford.

All the exterior work needs to be done in 2-3 days and made weather proof.

 

[Jasonb]

Try Arnold Laver, they have a branch up your way and do the Wisa Sprucefloor

http://www.laver.co.uk/panel.asp

No ply floor will give a moisture proof seal, you will need to lay a DPM (polythene) over the joists before laying the ply.

Noggins could be precut off site if you go the 8x4 route

I joists are an alternative to solid timber joists, they are more stable and come in longer lengths, also easier for services.

http://www.trada.co.uk/topics/engineeredwood/

Jason

 

[forestboy]

That's a good link, thanks. I knew them but becauae of where they are I thought they only did ships!

They can do ext T+G ply 18mm for 14.34 + vat and same OSB for 7.95 + vat.


The ply looks pricey, going to cost 500+ just to get the base set up. So OSB looks more attractive, but that's exterior 'water resistant'.

What do you think - put a waterproof membrane down only, or membrane plus varnish/PVA seal the underside?

Thanks for your help.

 

[squowse]

That's a good link, thanks. I knew them but becauae of where they are I thought they only did ships!

They can do ext T+G ply 18mm for 14.34 + vat and same OSB for 7.95 + vat.


.

is that for full sheet 8' x 4' ?

 

[forestboy]

That's for 8 x 2!

 

[Jasonb]

I'd go with the T&G ply and a DPM, nothing else, Just glue the joints with an external PVA wood glue. Don't fancy OSB as flooring. Thats about what I would expect it to cost for small quantities.

Jason

 

[Symptoms]

forest - I'm with Jasonb on this one! Also consider pre-fabricating the unit off-site then do a trial erect with all the large elements fastened with nut & bolts. Once it all fits hump it into the wild. As it all fits together the only tools you'll have to take into the woods will be spanners, hammer, level, shovel. No genny, no table saw, no corded power tools ... travel light

 

[forestboy]

Thanks for the advice.

One final thought - I'd normally stay away from chipboard because of the wetness of the site, but if I use a one piece DPM, which I then fold up over the flooring and secure with the base of the timber frame - isolating it from the outside, could I use P5 grade chipboard?

 

[Jasonb]

Stick with the ply.

Jason