How to attach double 190x45 bearers to posts - housing required?

[Michael80]

We're in the early stages of building a new deck. Roughly 1.5m high with 100x100 posts, double 190x45 bearers and single 190x45 joists.

I'd like to attach the bearers to the top of the posts using nails and hoop iron, without housing them into the post. Given the 190 depth of the bearers I'm a bit iffy about the lack of lateral bracing with them just sitting on top of the posts. Do they need to rebated into the posts to properly secure them?

There are 17 posts in total and I'll be using ironbark. Honestly I don't want to rebate double bearers into each if it isn't needed!

Any advice greatly appreciated! 

[MitchellMc]

Welcome to the Bunnings Workshop community @Michael80. It's brilliant to have you join us, and many thanks for your question about connecting bearers to posts.

The only stipulation I've been able to come across is "Bearers shall be fixed to their supporting stumps, posts or columns in such a manner as will give adequate bearing and provide restraint against lateral movement.". So, you'll need to use nailing plates or possibly hoop iron on the side faces of the bearer to retrain them on the post. Secondarily, your joists will be connected to them, which will also restrain their movement. Sections of 190x45 as noggins perpendicular to the bearers and between them at each post would also help prevent movement. Another option is a full run of 190x45 at either end of the bearers to connect them. I've created the rendering below to illustrate. 

Given this sounds like a deck of the size that will require council approval, I'd suggest you contact them to see whether you'll need an engineer to sign off on the deck to obtain permission. The engineer will ultimately decide the appropriate connection method for your bearers to posts.

Please let me know if you have any questions.

Mitchell

[Michael80]

Thanks for the quick reply and the render - very helpful!

To confirm we've got the deck permits and everything has been signed off by council. The permit just doesn't have any details on the join between posts and bearers, other than the comment the bearers should be "FIXED OVER STUMPS @ 2400mm MAX SINGLE SPAN". 

Regarding the idea of running a noggin between the bearers - our joists will be spanning up to 2.9m (hence 190x45 size). No issues with a noggin spanning the same distance?

I've attached a snip of the plans if that helps. 

[MitchellMc]

Right, that's a big span and huge joists, @Michael80.  Each of these hefty joists will be connected to the bearers with joist straps at 460mm spacings. I can't see much lateral movement of the bearers occurring.

Did you draw the plan up yourself, or did an engineer do it for you? Given the size of this structure and the spans involved, I'd be more confident in you seeking the advice of someone specialising in this area. Either an engineer, builder or carpenter should be able to assist. Also, it might be worth phoning the council to see if you can get ahold of someone there who can provide input into whether a specific connection method is required. If this was a low-level deck, that's one thing, but given it's elevated, I'd encourage you to speak to someone qualified in this area. 

Mitchell