Need a joist hanger for 45 degrees

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Benoire

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#303562 19-Feb-2023 10:25

I'm currently building a small deck that is around my new timber cabin. The deck is L shaped and is 4.5m long by 1.5m wide wrapping and around the front and one side of the cabin. I've currently got enough 90 degree joist hangers as the joist span is slightly less than 1.5m but where the corner of the cabin is I was planning on using a 45 degree joist as a bearer (~2.2m longish) to allow for mitered decking boards and a neater look but to mount it effectively I need hangers that are 45 degrees for both joists running in to this angled bearer.

I've tried my local M10 and bunnings and they dont appear to have any instock, just the normal 90 degree which I have enough off... So my question is, where can I purchase L/R 45 degree hangers or can I create the equivalent using things like nail plates, roof ties etc.? The joists/bearers are the same level and the bottom of them is at worst case 200mm from the ground.

Any help/direction is really appreciated as its been annoying me for a while now and I haven't got anywhere... The US use them a lot and they seem easily available there but not here?

Cheers

Chris

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edge
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#3038995 19-Feb-2023 12:00

If I understand you correctly, would you not just bend the back plates of the JH (i.e. the ones fixing to the "bearer") to fit - although, in any event, I would think fixing the 45 degrees intenal corner (vs the 135 degree one on the other side) would be a challenge?!! :-)

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mdf

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#3039000 19-Feb-2023 12:30

I'd probably just use some multigrip plates and bend them to suit. Won't be as strong as a proper joist hanger though. Is there any other way to brace it?

mdf

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#3039004 19-Feb-2023 12:33

And actually just rereading the OP, you want to use joist hangers for a bearer or have I misread that?

Benoire

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#3039018 19-Feb-2023 13:59

So to be fair, I perhaps didn't word my post as accuratley as I could so I've now produced a terribly wobbly image in Paint!

In the pictures, the yellow circles are areas where the 45 degree hangers would be needed. The 'bearer' is really a joist running diagonally between the outside bearers and the two joists closest to the cabin edge... the rest in red are simple joists.. the joists are 145 x 45 and teh bearers are doubled up joists... all sitting in 150 x150 piles.

I had though of the plates but as these are holding quite a large distance up I was looking to try and make something more robust...

scuwp

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#3039034 19-Feb-2023 14:36

Not sure you "need" hangers, you could build your own timber bracing. I would have thought the (angled) joints would be sitting on top of the 45 deg bearer, not butted up to it level. Wondering if you are over-thinking it a tad?

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Benoire

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#3039035 19-Feb-2023 14:37

The joists and bearers are all the same level, I don't have the depth to place the joists on the bearers otherwise it would not be an issue and this is why I am using the hangers.

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Clima

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#3039039 19-Feb-2023 15:03

Not an answer to your question -an observation. Most of the 45 degree mitred decks I have seen looked good when just done but as they dry out they are not so tidy. They take a lot of care to get right but timber does not always age gracefully !!

mdf

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#3039041 19-Feb-2023 15:12

So the light blue bearer is actually sitting on posts?

I haven't seen 45 degree joist hangers here. I suspect you would need to try somewhere very specialised or else a sheet metal fabrication place to produce something custom (I have just gotten a load of custom corner soakers made up and they aren't a million miles from a joist hanger). You other possible options (probably in order I would try):

- Cut some 45 degree blocks and (securely) bolt/batten screw those to the 45 degree bearer. Use standard joist hangers attached to the block. Just make sure the joist hangers go into edge grain rather than end grain.

- Multi grips / split joist hangers on either side

- Add another joist under the bearer but rotated 90 degrees to create something of a floor for the 45 degree bearers to sit on. Attach joists with brackets and cyclone ties

* Not professional builder, usual disclaimers apply

wally22

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#3039555 20-Feb-2023 18:11

How high above ground is the deck? Just curious.

I would recommend NZS3604:2011 free to download.

Section 7.4: Timber Decks plus the multiple references within that section. I know it is more timber etc but will be very stable on that outside corner. If you follow that, then all you will need will be a line of suitably cut nogs placed to allow nailing the 45 degree decking ends. Double nogs would be even more secure and allow nailing further back from the cut ends of the decking to help prevent splitting. Don't forget to predrill the decking before nailing, particularly on the 45 degree ends. I also do recommend the wider decking.

Happy to be contacted if you need more info

Tick

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#3039873 21-Feb-2023 08:06

You're not meant to run diagonal bearers. You do straight orthogonal lines of piles, which bearers sit on. The 90deg join of the bearers should have nail plates to secure them together. This is not to hold weight, but to tie them together so they do not move independant of each other. Your joists are then whatever you need, and the diagonal joist is simply fit between the joists as fixing. It doesn't hold the weight, so it doesn't require hangers.

This makes the piles easy to line up. The bearers should always run in straight lines to have the fewest possible joins. The joists are run first to support the weight of the deck boards and to give an even screw pattern. Then blocking is added for fixing so that you can run certain board patterns.

Red are bearers, green are joists, purple are fixings and non-load bearing joists. The perimeter joists and the diagonal are double joists

Froglotion

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#3040873 23-Feb-2023 13:46

Good advice ^^