Stumps for low level deck

Hi, great forum here.

Im building a low level deck, with limited clearance in Eastern Melb. Nice clay soil with lots of rocks!

I'm down to 500mm deep x 450 x 450 wide.

I will only have 150mm clearance between the underside of the bearer and the ground, so I'm curious about what stumps I could use?

I don't like the idea of concrete stumps, and am considering having the bearers sit directly in a pryda type stirrup, but cant find anywhere that says this is an accepted construction method? If this is ok, does the entire stem need to be encased in concrete?

The other option is TP H4 posts ontop of a 200mm thick bed of concrete, but obviously the concern is the post rotting out.

Bearer span is 1500 and joist span is also 1500 @450 centes so going to use 2/90x45 h3 for bearers and 90 x 45 joists.

Community manager's note: Check out How to build a low-level deck for expert advice.

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Comments

Jason

Hi @Crash76,

Welcome to Workshop.

That sounds like a great project. Have you searched "low-level deck" here on the site as it's a popular topic that has come up many times and you might find some helpful advice in previous discussions.

Let me also tag the very helpful @Adam_W who might like to share some of his experience with stumps.

We are looking forward to seeing your deck project come to life (with a bit of help from our amazing members). Feel free to post anytime you need a hand with anything.

Jason

ProjectPete

Hi @Crash76

H4 100x100 is perfectly fine for stumps, they're what I use. 400 deep hole that's 300x300. Make sure there's at least 300mm of stump in ground and set in RapidSet concrete making sure you get about 100mm of it underneath the stump.

I'd suggest using 140x45 for bearers and 120x45 for joists.

Importantly - are you installing timber or composite decking?

Adam_W

Hi @Crash76 and welcome.
Okay... unpack a few things here... as @ProjectPete said if using timber 100x100 is fine but yes, must be H4. Make sure as well that concrete is mounded up so any water can run away. The other option of-course is to use steel such as these (available in different sizes, just concrete the foot in)
For a low deck with stable soil post holes 500 x 450 should be fine but again... as @ProjectPete said don't sit your stumps on the soil, make sure there's either a layer of gravel or concrete underneath.
Or another support option for the centre posts at least that doesn't require holes...

Hope this is of some help...
Feel free to fire us any more questions.

Crash76

https://www.workshop.bunnings.com.au/discussion/comment/6826#Comment_6826

Thanks for the advice guys. Its quite simply a maze trying to workout footings for a deck. I like the foundation blocks, but cant understand how they are an acceptable building method as they just lay on top of the ground, yet if i dig a hole it has to be really deep to hold everything!

Going to go with 450 x 450 x 500 holes, have about 50mm of gravel, and 150mm of concrete leaving about 300mm of stump in the ground. Hope thats going to be ok! Im not using concrete around the posts, just backfilling with the clay soil.

CloudyHaze

Do you need a permit for new deck or extending a verandah/deck???

Jason

https://www.workshop.bunnings.com.au/discussion/comment/7491#Comment_7491

Hi @CloudyHaze,

Welcome to the Workshop community. We are pleased you could join us and trust that you'll get loads of helpful information, advice and inspiration for all your projects from our amazing members. Feel free to post anytime you need a hand.

We would encourage you to contact your local council regarding permit requirements as they differ according to your municipality.

Thanks,

Jason

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