Decking Experts...i have some questions :)

Hi there. I am due to lay some decking over an area of grass (and weeds) about 7.5m x 4.8m.
My question mostly relates to what to lay the actual joist frame on. i want to lay paving slabs along the length of each joist.
So if you imagine the joists are running along the 7m span of the decking area, i was thinking of laying weed membrane over the whole area, then on top of that putting 300mmx300mm paving slabs every 1.5m along where each joist would go, then laying out the joists and frame, fix the whole thing with noggins, and then lay my deck boards with a 3mm gap.
Would the paving slabs be sufficient to take the weight without sinking and is there any other issues you could find with my plan? all advice needed and appreciated! thanks

 

Let me start by saying I don't profess to come into the category of 'expert', but, with no previous experience (and a husband in the USA) I did single-handedly, build/lay our deck about 8 years ago, so these are just some 'thoughts' from a rank amateur.

Personally, I'm not sure I'd bother putting down the paving slabs - from the size of the deck you're planning, that seems an awful lot of slabs and expense to go to for something you're not going to see.

When I built our deck, I dug out the worst of the grass and weeds and just turned over the soil. Once the site was level, I put down 2 thicknesses of weed surpressing membrane and, over the top of that, a generous 4" - 5" of 20mm gravel (a Wickes 'Jumbo' bag - all 850 kg of the stuff! - which cost about £40), which I levelled 'properly' and then laid the deck joists directly onto the shingle - this not only allowed the joists to bed down firmly, but made it very easy to ensure everything was square (for which I made up a 3x4x5 triangle from bits of wood pilfered from Sir's workshop!) and 'spirit level' flat.

As to how far apart to put your deck boards, the 'recommended' distance is about 5mm, (to allow for the wood to expand and contract), which is fine if your finished deck area happens to lend itself to being neatly divisible by 'x' number of boards plus the 5mm gaps. Mine wasn't! That then meant I either had to cut one board along its length (as though I was about to do that!), or space them fractionally closer or indeed, further, apart. In the end I found (also in Sir's workshop) an off-cut of Whitworth studding which proved to be just the right diameter to allow me to lay all the boards without having to do any annoying 3.6m long saw cuts!

As I say, I wouldn't even begin to suggest I'm any sort of 'expert', but the deck is still there and still as solid, straight and square as the day I put in the last screw, so I hope this helps .... a bit.

 

Don't know if this will help, raised decking i've yet to finish (when client makes her mind up about the rails:DOH:

Wherever it touches the ground it has 18" deep x 12" square concrete pads, didn't take very long to do the footings & concrete is cheaper to do than slabs usually.

 

Well done, Ziggy - my compliments!

 

Cheers Lasses and Lads,

Not built one before, but I had some plans

The Noggins are the bracing bits marked up with the Roman Numerals.

Noggins are any bits like that used to make a stucture more rigid.

Also a measure of Rum Armandii

 

Nice deck ziggy, I'm not getting involved in this one.

Decking, tooo risky.:D

 

All i'll say is, don't let the client choose the timber from the internet.:DOH:

"Apparently" Soft yellow southern pine is the best thing for the actual deck:DOH::DOH::DOH:

Well it might be if you live in Texas but over here it just goes black with mold because it absorbs rain better than a Cypriot Sponge fishermans catch:DOH: and never dries out:DOH::DOH:

The next obvious question you have to answer(after all, you put it in:DOH is "How do I get the mold out of the wood?"

"You don't Madam, you listen to your builder next time"

 

Thanks for the replies!.... So your saying that i dont need paving slabs? Weed membrane on turf....gravel on weed membrane- joists on gravel- decking on joists! Bobs your uncle! Any one care to agree or disagree with that..... Because I'm liking the idea!
Good work ziggy, but mine is going flat on the ground, and I assume that with yours being raised on posts it will have weight on the pressure points therefore needing to be concerted in, whereas mine would have its weight more evenly distributed?

 

What about what Tommy Walsh does? (or at least did several times on Groundforce) He put down concrete blocks and stands the decking on those.
I was thinking that slabs may "snap"

 

Would agree you need to use either a concrete block or engineering brick to sit your joists on or your timbers will rot.You can lay concrete pads first then lay the block or brick with mortar on these. The membraine and gravel is your choice depending what you have growing under there .

Dave

 

Thanks again guys. I was hoping I wouldnt have to mix up any concrete or mortar. I have a lot of old slabs (about 35) and would only need to find anther 10ish... Do you really recon it would begin to sink on those? I thought being a large deck and on a lot of large slabs, the weight would be dispersed quite well.
Plus I restricted by height (door frame) so without digging out loads I wouldn't be able to fit slab, brick then joists.. But if that's what's got to be done. I suppose I should! :/ lol