New Deck: question about using post brackets

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lookout

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#243923 9-Jan-2019 09:40

Hi guys, building a new deck DIY. Have a question about post brackets. TIA for any advice.

Where I need to put one of the post holes (front corner) I cannot dig the hole deep enough. There is concrete from an old deck post in the way. So I'm thinking I could dig a smaller hole here and use a post bracket for that one post. Something like this Bowmac bracket.

Will a post bracket like this be stable enough? or is there another option? What size concrete footing would it need?

For reference: the rest of the holes will be 450-500mm depth and 400mm sq width. I will be using 125mm x 125mm posts set in concrete. Spaced 1200mm apart along the bearers. The finished deck will be 1.4m high.

nickb800

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#2156860 9-Jan-2019 10:25

Posts serve two purposes - weight bearing and bracing. Weight bearing wise, you've already got a bit of deeper concrete there, so you'll be sweet. Bracing wise, there should be 3 nearby posts in your grid that can provide bracing for that area of the deck. If you find that it's not solid enough once you've completed it, then you could just add some diagonal braces between those posts.

Is the shallow post going to be on a corner, edge, or in the middle of the deck?

That bracket does need a bit of concrete poured around it, will there enough depth above the old concrete foundation to properly encase it? Otherwise you could get a simple U shape bracket without the flayed legs and bolt it into the existing concrete footing

k1w1k1d

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#2156880 9-Jan-2019 10:49

Might pay to check with your local council as I think decks over 1m need a building consent?

nickb800

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#2156886 9-Jan-2019 10:58

k1w1k1d:

Might pay to check with your local council as I think decks over 1m need a building consent?

1.5m is the rule, so the OP just sneaks outside of building consent requirements

k1w1k1d

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#2156955 9-Jan-2019 12:19

Some councils have a different height limit. They also have rules about railings etc. So I would still suggest checking first.

nickb800

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#2156966 9-Jan-2019 12:33

If the OP's council suggests a consent is required for a deck under 1.5m then tell them to re-read Schedule 1 of the Building Code.

I'd suggest the BRANZ timber deck guide for details around foundations and railings as councils are often reluctant to give design advice due to potential liability

Dial111

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#2156972 9-Jan-2019 12:46

Each local council varies but one thing you cannot overlook is the building code, that’s gospel so you must build to the code.

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lookout

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#2157124 9-Jan-2019 15:43

nickb800:
Posts serve two purposes - weight bearing and bracing. Weight bearing wise, you've already got a bit of deeper concrete there, so you'll be sweet. Bracing wise, there should be 3 nearby posts in your grid that can provide bracing for that area of the deck. If you find that it's not solid enough once you've completed it, then you could just add some diagonal braces between those posts.

Is the shallow post going to be on a corner, edge, or in the middle of the deck?

That bracket does need a bit of concrete poured around it, will there enough depth above the old concrete foundation to properly encase it? Otherwise you could get a simple U shape bracket without the flayed legs and bolt it into the existing concrete footing

Cheers. This is good info. I had thought about bracing it diagonally as it is the front corner of the deck. There will be 3 bearers total so I can brace it to the 2 closest posts in an L shape, if that makes sense.

I am intentionally keeping the deck under 1.5m to avoid consents. I have checked with Auckland Council and it's all ok. Also to add, it is an extension of the existing concrete porch but it will be freestanding.

DarthKermit

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#2157141 9-Jan-2019 15:49

Are you able to knock a hole thru the existing old concrete to make a deep enough hole for your post foundations?

For a deck of that height, I'd dig the foundations a bit deeper to be on the safe side.

Fred99

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#2157640 10-Jan-2019 15:20

You should be able to smash out the old footing with a decent hired jackhammer in a couple of minutes. Even a ~$100 3-way Ozito rotary hammer drill from bunnings should deal to it with a little effort.

Brunzy

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#2157659 10-Jan-2019 15:50

Cant you dynabolt one of these to the old concrete, also bowmac , at the bottom of the post.

antoniosk

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#2157688 10-Jan-2019 17:05

nickb800:

k1w1k1d:

Might pay to check with your local council as I think decks over 1m need a building consent?

1.5m is the rule, so the OP just sneaks outside of building consent requirements

As I recall, wellington required 1m down for 1.5m out of the ground... but maybe thats because hills holding back weight etc. 500mm doesnt feel deep enough for a 1.4m high deck

________

Antoniosk