Thread: Should I (and How Do I) attach Deck Bearer to House Post?

Originally Posted by Son of a Beach

Is it OK to support the new bearer using the existing house stump?

If this is OK, what is the best method to use for attaching the new bearer to the existing pole?

If you don't know should you really be doing this by yourself?

It's not like you are making a coffee table or something that doesn't have dire consequences if it fails.

Sounds like the kind of building job you might need a permit for as well.

Thanks.

So in the plan to be included with my permit application... What would be acceptable?

I have found people in the council offices to be most unhelpful at telling me what would or would not be acceptable. Fair enough, it's not really their job. The only way they will answer a question, is to:

1. Submit a permit and then they will tell you (one of the reasons) why they rejected it.
2. Point you at the many-thousand-page building code that is beyond my ability to understand.

It would be nice to get the plan right first time around, eh? So I thought it would be prudent to seek the advice of people who know better than I.

If this is the wrong place to ask this sort of question, then I humbly apologise.

How high is the existing deck? Above a certain height, decks need to be Certified and from the sounds of it, you may need to get a structural engineer to certify also the extension as well as the beam you are asking about. From my limited experience of the BCA (NCC) I’d suggest that the new beam would have to have its own post, some distance from the house stump footing, and then the beam be non load bearing attached to the house stump (effectively giving a cantilever from the dedicated new post).
Tasmania also has specific BCA inclusions which may or may not affect your deck


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Food for thought. Thank you.

The deck is about 800mm off the ground.

It is normal practice to attach a deck to the side of a house. The piers are part of the side of the house. Provided the piers are not compromised there is no reason not to attach bearers to them. (Lic Builder)

Hi, I agree with rustynail. As an ex builder and licenced drafty now retired I would suggest that if you attach a treated pine plate (bearer) to the house stumps with appropriate fixings this is would be ok. Of course this would only apply if it is just a deck and the other stumps and bearers are spaced correctly.

Depending on your exact existing conditions maybe a 150x50 treated pine plate attached to the house stumps with 2 M12 gal coach bolts at each stump would work.

Can I suggest you seek out a local licenced drafty and ask for some advise. Unless you are doing something other than a standard deck you may not an engineer,

George

Originally Posted by Son of a Beach

Food for thought. Thank you.

The deck is about 800mm off the ground.

800mm dramatically reduced the PITA factor. If it was 3m off the ground, I’d go the certified route.
NCC 2019 has a section dedicate to attachment of decks and balconies to external walls. I’ll have a quick look, but anything I say is my opinion and you need to seek your own professional advice


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NCC2019 has too many requirements to give a straight forward black and white answer. I’d get an experienced drafty as has been suggested, to look into it.
Fixing of deck supports to me appears to be required at 600mm centres, so if you can’t achieve that fixing spacings, you need more posts etc. doubly so if you are in an alpine area of Tassie, being Ben Lomond ski field, cradle valley, Great Lake area or mount field ski, which as I’m typing this I can see straight away won’t be applicable.

If it was me in this situation, I’d be building the deck separately off the house with new posts


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Get an engineer to appraise (on site) your existing structure, prepare the engineering design, have your drafty do the required drawings and submit both to council, basically this is what the previous experienced posters have indicated.

Thanks to all for the advice and input. It seems there are a few different ideas on how to handle this situation.

As is obvious, I'm not confident in my own abilities, and I am likely to recruit some more experienced help for this part of the construction. But it is good to get a few ideas on how I might be able to proceed.

This is basic timber framing code stuff (AS1684.2). You can download free timber design software that can help you with your planning application. You can also use span tables but the software can print out all the calcs if council request them. DesignIT is a pretty good one and guides you through the process in terms of what data you need to input. It provides diagrams, usually lifted straight from AS1684, that show you what to provide in each entry box. You can design in LVL or MGP10 timber as well as others, Glulam, F17 etc.

The NCC isnt that hard to follow and can provide good information for attaching an end bearer to your existing structure. Your best option is to place new posts as close to your existing structure as you can to minimise the load on this end bearer and then you just oversize it (i.e. you make it the same size as your other bearers.

I might be able to help further if you can provide a sketch of what you are trying to achieve.

Thanks again for the various suggestions and advice. Just to close out this thread...

I ended up installing a new post/footing, and attaching the bearer to this. It was the simplest and safest solution for my abilities. As it turned out, the clay was just the right consistency for digging. Usually it is either rock-hard, or too sticky. It was goldilocks clay on this occasion.