Shed flooring / joists size question

[functor]

Hey all,

So I am building my first shed, and I am designing the flooring / joists and how they will fit together. From what I kind find on the market for joists... I only see 2.4m, 3m, 4.2m, 4.8m etc cuts. For this shed, I was thinking of using:

Pressure Treated Softwood Joist Timber - 47 x 150mm x 4.8m / 3.0m C24

I was thinking of making the shed 3m x 5m.

Thats fine so far... so then I look at Marine Plywood for the flooring. It only comes in 1220x2440 cuts. OK, so I draw how the Plywood will fit on various configurations of the joists.. and its SLIGHLTY off by a tiny fraction in each way I can think of.

Untitled

• functor
• 20 Dec 2014
• 1

I have two options.. cut the timber or buy an extra plywood.

If I cut the timber, I would have to "treat" the edges again, how hard is that? Is it easier to just get an extra plywood and use the extra to make a desk or shelves or something?

Thanks

 

[scbk]

Try and work around standard timber sizes unless the shed has to fit a specific space.


What is the shed going to be used for? 6x2 is a hell of a size for joists!
My shed here has a 3x2 framework with approx. 22mm thick 2nd grade boards/planks on it and that is rock hard, totally bomb proof. Raised off the ground on concrete blocks and a bit of DPC

 

[functor]

It's going to store a lot of stuff (various old electronics and hardware), some might be a bit heavy.. But yeah since the price difference isn't so big, I would rather be on the safe side. The american specs for joists all say 2x6 (I guess because it's windy as heck in the US).

I am also going for 16'' OC on everything. The studs are "2x4" (actually 38mm x 88mm after it's "processed"). They are pretty cheap and are designed for studwork and are C16.

I guess since I don't want to risk cutting the joists and ruining the treatment (rotting joists is the worse thing..) I'll just get an extra sheet.

By the way, my next question would be about my slab. I have an existing slab with DPC that used to house a 3m x 3.6m shed. Basically, if I re-use it I would have my floor hanging off the side by 1.2m.

I have some rubble from a demolished brick extension, can I just put a DPC and then some of the bricks / rubble on top to support the "hanging" part? I am trying to avoid getting a new concrete slab because the back of my house has no access.. hard to get in.

 

[wrathkeg]

The american specs for joists all say 2x6 (I guess because it's windy as heck in the US).

How cheap and easily available timber is in the US compared to the UK is probably also a factor. If you bought 6x2 at Home Depot (a sort of US equivalent to B&Q) it would cost the equivalent of about £1.50 a metre. You can't buy 2x2 for that price at B&Q. I don't know if they even stock 6x2.

 

[functor]

I would never buy timber for wickes or B&Q tbh, I was looking at this place which has 2x4:

http://catalogue.chilterntimber.co.uk/product26310625catno780625.html

At around £2.95 per 2.4m (this is studding timber though)

It also has 2x6 pressure treaded Sawn KD for joists at around £2 per metre:

http://catalogue.chilterntimber.co.uk/product26190625catno130625.html

I am not sure about quality as I haven't ordered anything yet, anyone got any experience? They are 30 mins from my house so I was gonna go collect.

 

[wrathkeg]

All I meant was given scbk's post about joist size that the reason you are seeing a lot of those larger joists on US plans might be because of their availability/price, not because they are required.

 

[functor]

Yeah makes sense, it's the same in Norway, everything is wood-built over there.

 

[big-all]

ok my floor is in a grid pattern at 24" centers
pilars formed off slab/part slab on compressed sand with a brick part brick bit slab whatever brings it up to the level required topped with felt or dpm then 2x3 treated [6x2" ripped down the middle as cheapest option] as floor joist with 18mm ply floor and roof

all the structural timber is 3x2" but not treated above floor level

http://s21.photobucket.com/user/bigall2005/media/e1e47346.pbw.html?sort=3&o=15