Fixing a Deck to a Curved Wall?

[Clive McF]

Hi All,

I'm building a pool deck which will have a curved brick wall running along one side. Normally I'd just bolt a ledger to the wall, but the curve presents a few problems. The curve is convex, ie the wall curves in towards the deck, with the centre being further in to the deck than the ends. Anyone have ideas as to how best to do this? I wondered about putting partial saw cuts through the thickness of the ledger so I could bend it to the curve, but this might weaken it too much? Or I could use several short lengths, but even then they wouldn't have much area of contact with the wall. Or I guess I could fasten the joists to the wall with individual hangers but that's a lot of dynabolting and drilling. All advice would be very welcome.

Cheers

Clive

[Gaza]

what about gal angle to support the joists, better than hangers as has more meat and would require less fixings than say a joists hanger.

[Clive McF]

I wondered about that, but if using one piece of angle per joist I'd still need 2 bolts per joist, no? I guess I could get one long length of angle cut and welded up to match the curve of the wall, but this would be very expensive I'm thinking?

[echnidna]

Omit the ledger altogether and put stumps in.
Bearers go from stump to stump so that the joists will overhang the bearers and go right to the wall.
I would keep the joist overhang to 300mm or less.

[Clive McF]

Problem with that is that it's a new wall so the backfill isn't compacted and wouldn't take the loading of the stumps: I'd need to dig down about a metre till I hit the footings of the wall to take the load.

[echnidna]

a metre's not that deep

[Clive McF]

It's a lot of concrete...

[echnidna]

use a treated pine soleplate and stump, no concrete needed

[brynk]

you could direct-bury your posts then you wont even need concrete. a h4 treated pine post with the ends sealed with paint/wax/etcet and any cuts re-treated will go 40 years in ground. or you could consider any one of the aussie hardwoods rated at h1 durability - untreated they will do 25-30 years depending. have a read of the post on our deck for directly burying ironbark posts, and a method of squaring them up that my brother suggested - placing a rubber mallet against the post and striking the face with a gympie (or lump) hammer while someone else pulls the stump towards square. get a rythm going and the vibrations displace the backfill around the stump slightly and it moves towards plumb.

here is a study done by the fwprdc - http://www.fwprdc.org.au/content/pdfs/PN04.1004.pdf - the in-ground natural durability of aussie timbers

i can also suggest a stumping shovel - they're like a giant pair of pliers with shovels on the end - you can fill the handles with sand to put weight in them & you will chew through down to a metre in no time. a decent set will set you back 80 bucks and a shyte one maybe 1/2 that.

r's brynk

[journeyman Mick]

What about getting a length of sreel angle rolled to the radius of the wall and bolting that on as a ledger. This is often used on commercial jobs.

Mick

[Clive McF]

I must admit, of the suggestions made so far (thanks, everyone), using the wall seems the least hassle. But as I mentioned earlier, getting angle made up would be expensive I imagine? Any thoughts as to what size angle would be needed?

[journeyman Mick]

Probably 75 x 75 x 6. Places that roll curves would do it in a few minutes. I think if you offset the labour costs involved in the other methods then it would probably work out pretty cheap to buy the steel and get it rolled to your radius.

Mick

[Pusser]

You could laminate a ledger. Use boards thin enough to follow the curvature and use enough concrete screws to hold it to shape. Glue nail subsequent thicknesses and use nails as clamps. Put dynabols through the whole laminated sections when dry. If you did it this way even a few kerfs would not matter as long as they did not line up with each other. Just a different option to consider.

[Clive McF]

That's an interesting thought: you'd use the concrete screws to hold the boards to the wall while building up the laminate? What size and type of wood would you use (I'd guess the radius of curvature is around 5m)?

[Pusser]

Please note my idea was just a sugestion as to how you might approach it seeing you were reluctant to get a fabricated steel piece and the stumps idea was not attractive. It was a left field solution I adapted from historical WW2 boatbuilding (no I wasnt there!). I thought someone might pick it up and run with it.

Having said that I would approach it using the species and sizing as if it were a straight ledger except I would move to the next size in depth as you may have to kerf the timber. The width would be the same finished size but a laminate rather than a solid piece. Assuming you wanted a finished width of 50 mm then ideally you would use 10 mm laminates assuming the timber you want will take a 5 metre radius. At 10 mm I think most would but not sure. Otherwise you could use 19mm and kerf it. Providing you do not line the kerfs up it should be no problem once glued and bolted. I would paint preservative on the back of the board going next to the brickwork, screw it into the brickwork at the centre and move outward arttaching it with those blue brick screws. You would not need to secure it to take the weight of the deck but still hold it firmly to resist the pull of the other laminates until you through bolt it. Use waterproof glue, (slow setting epoxy) and attach the next laminate working out from the centre again - a nailer would be useful here. I would glue in sections a metre or so at a time) The nails clamp the laminate so you will need a few and it would be best if they were sKewed. Repeat for subsequent laminates. You would not need to wait for the layers to dry. When the laminate is finished drill through the laminate. and into the brick work with some ramset bolts and do them up tight. You will probably have to clean up the top unless you use a glue that sets slowly enough so you can clean up each laminate.

As I say this is only an idea and I have not tried it but it is the way they used to build wooden minesweepers out of douglas fir and mahogany except they used copper nails to secure the laminates. the curvature on ships hulls was considerably more complex than the structure I think you are doing. The laminate should be as strong if not stronger than a solid piece even with kerfs. If you have to kerf make sure the kerfs are evenly spaced and start at a different distance from the end so none line up.

I would do it this way but I think you should get a second opinion before you try it on my say so.