Bracing off treated pine sleepers.

[Dr - 307]

Fellow forumites,
Attached are three photos of the area a client wants me to deck over including around the tree. The drop to ground is only 650 - 700mm.
I was going to wall ledger off the treated pine sleepers with suitably sized coach screws. And for extra reinforcement maybe even add housed out (coach screwed into the TP also) mini-posts on all the corners of the area.
The framework is not an issue. Just double checking the wall ledger theory around the perimeter. Not keen on digging because of the roots but realise there will have to be one stirrup in the corner which leads into the back of the pool infront of the pavers in pic 3.
By the way, the retained area is filled with soil and crushed rock so sleepers ain't moving and the I-section and C-section for the retaining wall is sitting 1 metre into the ground.
What do ya think?

Dr - 307.
Attachment 66533 Attachment 66536 Attachment 66539

[Dr - 307]

Actually I just realised that it would be no different to hanging joist hangers on the inside face of a bearer with coach screws like I did on the deck. So coach screw the ledger on and then attach my hangers to the ledger either with coach screws or gal. joist hanging nails like normal.

[silentC]

The only reservation I'd have about it is whether or not the sleeper is likely to move - ie shrink, warp twist etc - in terms of what that might do to the level of the deck over time. Other than that, I don't see an issue with it.

[Dr - 307]

Took ya bloody long enough. Where ya been? Doing some work have ya?
Thanks mate.
We'll worry about the sleepers at a later date. The area is only 2500mm square. Not a big area to worry about.

What about the footing for the one post in pic 3 near those pavers. Worried about the tree roots. What about if I boxed up a concrete pad and bolted a stirrup to it? Then again, maybe I should try my luck and dig a proper hole so that I can brace the steps of it at a later time.

What do ya reckon?

[silentC]

I reckon you've got about a 95% chance of hitting a bloody great root. But then I don't see you've got much choice. You can't cantilever it. Unless you can get a post in further away from the tree (closer to the camera in pic 3) and run a bearer right along and then hang your joists left to right. I presume that's the way you want the decking to end up anyway - parallel to the fence so you're not looking along the gaps when you look towards the tree?

Is there meant to be access around the back of that wall in the foreground? Where are the steps to go?

[Dr - 307]

I wanted to run the decking across the front of the tree in pic 1. But when I put the steps in which will be placed in front of the camera in pic 3 the boards won't match cause when on the steps you will be walking on boards running across your feet but will be walking up to boards running perpendicular to you and hence looking through gaps.
What I reckon is that the steps are only accessed to get to the pool equipment and nothing else so the main priority is for the deck to look good from the concrete area looking at the tree like in pic 1. So I'll run the boards across the front of the tree trimming around it when need be and of course across the back of the tree. So in effect, parallel with the front concrete edge in pic 1.
What about a concrete style pad for the post where I can't run a ledger. Even if I can get 300 in and fill it, it should be strong enough shouldn't it?

Have a think and let me know, gotta run.
Thanks for the imput,
Cheers,
Dr - 307.

[silentC]

OK, here's what I would do:

Put a pad in roughly adjacent to that post behind the retaining wall in pic 3. It would be in line with the edge of wall with the slab on it in the background.

I'd put a post and stirrup on this and run a bearer from the wall in the background, past the tree to the top of the post. This would be 19mm below the finished level of the deck and inset from the face of that wall by about 20mm for a 90mm decking board/50mm bearer. I'd support it at the far end on a post either secured to that wall, or on a pad next to it. So you end up with a bearer that runs across behind the tree, from the corner of the wall on the left in pic 1 to the post adjacent to the retaining wall post in pic 3.

I'd bolt or screw a ledger to the wall in front of the tree and sit the joists on this. The joists would butt into the bearer at the back with joist hangers, so joist and bearer are in the same plane. I would frame up around the tree, leaving a good 4 or 6" clearance around the trunk.

I'd frame up the steps so that the last tread finishes level with the post. Then I would lay the deck on the top part and the stairs. The last decking board nearest the fence runs right through over the top of the bearer all the way to the post - this is why the bearer is inset, so the last board overhangs about 20mm either side of the bearer.

Then I would fix decking horizontally between the post and the stair risers to cover up the exposed part of the bearer and the post, making a screen so that when you're looking from the yard towards the fence, you see the horizontal decking and the stairs disappearing down behind the wall, rather than a hole and then the fence. The top board here sits under the last board that is overhanging the top of the bearer, so you get a nice finished edge with a very slight overhang (1mm) so you don't see the top edge of the horizontal board - details are important

That way, you get a good footing for the post clear of the tree and the horizontal decking screen makes it look like you designed it that way. It will look good, trust me

[Dr - 307]

I printed off your reply and mulled over it over lunch. Everything was exactly as I thought except the brilliant idea of extending the run of the deck to extend past and behind the pool retaining wall before adding / starting the steps.

I'm gonna perimeter board this job as well and take on board all your points. I will perimeter board right around the back of course. The decking boards will run from left to right in pic 1 and disappear behind the pool retaining wall. The steps will run the other way of course across your foot.

If I can't dig a decent hole for a footing how deep should I make the pad?

And you're right, it will look awesome. But it was my idea....right?

Dr - 307.

[silentC]

Re. the pad, they're usually something like 500mm sq. and 600mm deep, so if you had a mass of concrete that size, I don't see why it wouldn't be OK but it needs to be founded on solid ground or rock, so you'd have to dig down deep enough for that.

[Dr - 307]

Might as well try my luck and dig 300 x 300 x 600 deep and jab a stirrup into it....true?

[silentC]

I don't know mate, I think 300 square is a bit on the small side. It might be over kill, but I always go for at least 500 square. That's the size the engineer specified for my carport in Sydney, so I always took that as a rule.

[Dr - 307]

I'll go 350 but no more than that. My council in Melbourne approved a verandah for the rear of my house with 350 diameter holes. I'll do that.

All good with all the other stuff?

[silentC]

OK fair enough. I'm no engineer but it looks OK to me. It's not quite what I was suggesting, but I think running the deck through behind the wall is as good if not better, as long as there's room to fit the steps in before you run into the pool filter or whatever is down behind that wall.

[Dr - 307]

That's what I'm gonna do, run the deck behind the pool wall. There should be enough room before the pool stuff. If not he can live with a 'hole' leading to his steps.

Before I start anything though I'm gonna dig a hole for the post stirrup to see if I can actually dig there. If that's OK then I'll proceed with the rest.

Cheers,
Dr - 307.