deck framing

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arturv

9 posts

Wannabe Geek

#225457 20-Nov-2017 11:46

Hi,

I'm building a deck using Lumberlok solution for balustrade and joist fixing as shown here:

The problem is that the deck corner is not 90 degrees but closer to 45:

As you can see, we can't use 90 degree corner brackets and there are no variable angle / skewed joist hangers sold in NZ (Joist size is 140x45)

We are applying for building consent so we have to show that our solution complies with NZS for horizontal load
of 0.75 kN/m on handrail etc.

Can it be solved with simple blocking or do I need to get structural engineer involved? Ideas? Thanks!

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1522 posts

Uber Geek

#1904479 20-Nov-2017 12:10

To save time and money get a engineer involved otherwise you may end up going backwards and forwards until the council is happy.

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Rickles

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#1904818 20-Nov-2017 20:23

Give McGuire Enterprises Ltd a call and have a chat ... even if just a consult fee it should help you ... they are also near you for a lunch-time visit

http://www.mcguire.net.nz/Home/

wally22

504 posts

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#1904834 20-Nov-2017 21:18

You can use Lumberlok Nailon Plates, available in various widths and cut to 400mm increments. Some places don't stock many but they can order them in. Bend them to whatever angle you need to. Get large sizes so you can use more nails = higher rating. Note I do not mean Nail Plates, the ones with the nails formed from the plate. These really should be pressed on as is done in a truss plant.

Telephone Mitek for advice if you are not sure what sizes to use.

Where the joists come in at acute angle as in your drawing, you can insert a shaped block and bolt it through. Overengineered is better than under.

If you need more help after that, I am happy to help if I can. Maybe can look at it next week, quite busy at present.

jjnz1

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#1904840 20-Nov-2017 21:29

Dont use joist hangers?

Is it a deck supporting a cantilevered balustrade? (where are your bearers?)

Fred99

13684 posts

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#1904983 21-Nov-2017 08:37

Builder friend of mine constructed a deck without joist hangers by bolting a 90x45 at the bottom of the edge/ribbon beams to form a ledge that the joists sit on. (ie if the beams are 245 deep and the joists 190, then the 90x45 can be fixed to keep the top of the beams and joists flush). I cant remember the fixing detail, the work would have involved a structural engineer, it was part of the rebuild of his own home, as a licensed builder he was able to DIY the restricted work.

Note that Mitek state that SS hangers should be used for exterior exposure, these are damned expensive ($8 each or so IIRC) - quite a cost when you're buying in lots of 50 or so, and trade price discounts not very big - 15% or whatever, vs usually over 50% for other fixing hardware.

Bung

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#1904990 21-Nov-2017 09:08

Listening to a video about the Lumberlock solution the rationale for the fixings seems to be allowing different joist depth and avoiding all the visible fixing on the face of the boundary joist in the 3064 solution. I must admit the deck on the house above us looks like the rivetting on the side of the Titanic with 2 x 12mm screws into each joist. If your joist depth is >190mm can these methods be mixed?

arturv

9 posts

Wannabe Geek

#1905157 21-Nov-2017 11:33

thanks everyone!

I will try to come up with a solution and get the council to look at it one more time before contacting the engineers (Wellington council provides up to 2 hours free consolations with their builders)

Current design is looking a bit crazy and it has one last questionable weak spots where a joist meets the angled inner joist and it is not supported by the bearer. This is where I might use suggested Nailon Plates. The excessive number of fixtures is going to crack one of the joist:)

I'm pretty much restricted to Lumberlok solution as its the only propriety system that supports 140x45 joists. 190x45 is too wide for.. reasons

to see the deck in context, here is one of the early designs in webgl :)

http://www.vill.ee/deck

cheers

kryptonjohn

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#1905247 21-Nov-2017 13:34

Our new deck has a structurally awkward angle. The engineer used a steel vee plate with 4 12mm SS bolts each sude to join the angled boundary joist to the main joist - I'll try to remember to get a photo...

arturv

9 posts

Wannabe Geek

#1905262 21-Nov-2017 13:41

kryptonjohn:

Our new deck has a structurally awkward angle. The engineer used a steel vee plate with 4 12mm SS bolts each sude to join the angled boundary joist to the main joist - I'll try to remember to get a photo...

very curious to see! might be a custom plate. thanks John

kryptonjohn

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#1905264 21-Nov-2017 13:47

arturv:

kryptonjohn:

Our new deck has a structurally awkward angle. The engineer used a steel vee plate with 4 12mm SS bolts each sude to join the angled boundary joist to the main joist - I'll try to remember to get a photo...

very curious to see! might be a custom plate. thanks John

Yeah it is custom. Part of a set of engineered steel work for this deck - two beams and several posts. The main joists are all on stainless joist hangers fixed to a timber plate bolted into the channel of the steel portal beam.

wally22

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#1905458 21-Nov-2017 20:31

kryptonjohn:

The main joists are all on stainless joist hangers fixed to a timber plate bolted into the channel of the steel portal beam.

This plate is known as a Beam Packer, usually bolted at 600mm centres.

kryptonjohn

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#1905461 21-Nov-2017 20:45

wally22:

kryptonjohn:

The main joists are all on stainless joist hangers fixed to a timber plate bolted into the channel of the steel portal beam.

This plate is known as a Beam Packer, usually bolted at 600mm centres.

Noted!

kryptonjohn

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#1905466 21-Nov-2017 20:55

kryptonjohn:

arturv:

kryptonjohn:

Our new deck has a structurally awkward angle. The engineer used a steel vee plate with 4 12mm SS bolts each sude to join the angled boundary joist to the main joist - I'll try to remember to get a photo...

very curious to see! might be a custom plate. thanks John

Yeah it is custom. Part of a set of engineered steel work for this deck - two beams and several posts. The main joists are all on stainless joist hangers fixed to a timber plate bolted into the channel of the steel portal beam.

This is the vee bracket I mentioned. Fabricated by Black Steel in Auckland, who also did the posts and portal frame.

arturv

9 posts

Wannabe Geek

#1905573 22-Nov-2017 07:48

thanks John! this is helpful.

arturv

9 posts

Wannabe Geek

#1905991 22-Nov-2017 20:46

came across a deck with non-right angle joist fixings:)

bent lumberlok cpc80 bracket. I did't know you can do this.

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