Low level deck

Hi everyone. New to the website. Looking to build a deck at the girlfriends house. Any advice on ticking all the boxes would be really appreciated.

First issue I face is the lack of clearance under the deck, is this something I can resolve using H4 timber. I’ll will have to dig out and remove some sand. Is there a minimum gap that is required underneath the frame?
This is what I’ve got planned so far.

Size of deck 4.8x2.6m
Bearers 140x45mm @ 1300mm centres (should I go double bearers?)
Flush joists 140x45mm @ 400mm centres using joist hangers.
Thinking of using stirrups though unsure on the spacing.
At this stage thinking of building and installing the frame in two modular section of 2300x1400mm.

Pretty new on the DIY game so any advice would be great.
Cheers

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

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Comments

Jason

Hi @dazezy,

At the bottom of this page under You might also like.... you will notice that low level decks are a common challenge for Workshop members. I would encourage you to check out the other discussions as they contain plenty of helpful advice.

Let me also tag some very helpful members who might like to kick off the discussion for you: @Adam_W, @Brad and @ProjectPete.

Great to see you make your first post on the site after being a member for a while. We are looking forward to seeing many more and seeing your decking project come to fruition.

Jason

ProjectPete

Always love a good deck @dazezy

You should have minimum 200mm but ideally 250mm clearance for H3 timber.
You can use H4 to overcome the clearance issue but it can be harder to work with. I tend to use it for borders where I can't get the right clearance due to adjoining features (grass, pool etc) then H3 for the remaining frame.
140x45 for bearers is ideal although the 1300mm centres is overkill, you can easily push that to 1500mm.
120x45 is more than enough for joists and 400-450mm centres depending on the decking material you're using.
I just concrete posts into the ground using H4 100x100mm posts rather than stirrups but totally up to you. I'd do 4 posts (1600mm spacing) for the 4.8m side and 3 posts (1300mm spacing) on your 2.6m side. 1800mm spacing is fine for 140x45mm bearers but the suggested spacing keeps things even without exceeding 1800mm.

What sort of decking are you finishing it with?

Where are you located?

dazezy

https://www.workshop.bunnings.com.au/discussion/comment/8220#Comment_8220

Hey Pete, appreciate your quick reply and helpful advice. I live in Perth and at this stage going for a composite board, prob Ekodeck from Bunnings.

* Will 120x45 bearers still be okay for this board?

* Thats a lot of dirt to remove, i think just over 3 cubes. Do you think H4 would be worth it. Also what do you mean about H4 being harder to work with?

* H4 posts sounds like a good option. What diameter/depth would you suggest for the hole?

Thanks again for you help

Darren

ProjectPete

https://www.workshop.bunnings.com.au/discussion/comment/66292#Comment_66292

I'm in Perth too - will make it easier to help. Also means you can benefit from my trade pricing for materials including the decking.

140x45 for bearers, 120x45 for joists.

H4 often isn't as straight so makes it harder to work with over an entire deck frame.

You want the hole to be 300x300x350 with 300mm of the H4 post to be in the hole, leaving about 50mm space at bottom of hole so the concrete sets under and around the post. Make sense?

ProjectPete

https://www.workshop.bunnings.com.au/discussion/comment/66292#Comment_66292

I also suggest having your finished height of deck higher than the existing paving.

It gives it more of a feature and creates dimension/levels in the space. Cheeky side benefit - also reduces how much sand you need to remove for the clearance 😉

dazezy

https://www.workshop.bunnings.com.au/discussion/comment/95894#Comment_95894

Excellent thanks.
Understand the last part in regards to the posts 👍🏽
Starting to tick a few boxes.
In regards to fasteners Pete, what would you use for the frame and connecting the posts?

ProjectPete

https://www.workshop.bunnings.com.au/discussion/comment/114534#Comment_114534

You can go with M12 cuphead bolts or the easier cost effective and still strong option is 125mm 14g batten screws.

Make sure all fasteners are Class 3 Galv or Stainless Steel. Zinc coated will corrode in H3/H4 pine.

ProjectPete

https://www.workshop.bunnings.com.au/discussion/comment/114534#Comment_114534

If you join the bearers to posts with a rebate (most solid join) then 100mm batten screws are obviously sufficient.

ProjectPete

https://www.workshop.bunnings.com.au/discussion/comment/114534#Comment_114534

This is the rebate join I mentioned https://www.workshop.com.au/t5/Outdoor/Decking-frame-bearer-stump-rebate/m-p/33659#M5521

dazezy

https://www.workshop.bunnings.com.au/discussion/comment/125032#Comment_125032

Great thanks. Actually did a bit of googling after you mentioned it. I’ll give it a go

ProjectPete

https://www.workshop.bunnings.com.au/discussion/comment/132079#Comment_132079

Sounds good. Feel free to reach out with any other questions and remember that when you have your materials list I'm happy to order it for you so you get my trade pricing 👍

dazezy

https://www.workshop.bunnings.com.au/discussion/comment/136367#Comment_136367

Thanks Pete. Hey just a quick question about the clearance. Would you go about clearing the whole 2.8x4.6m area 200-250mm or only certain sections. Just a large amount of dirt to remove.
Thanks

ProjectPete

https://www.workshop.bunnings.com.au/discussion/comment/139302#Comment_139302

It really is the whole area mate although you can have less clearance against the H4 timber for the outside of the frame if you go down that path @dazezy . It's worth the extra effort up front to avoid issues with the timber frame (and timber decking) down the track.

Are you going with the raised deck suggestion? It looks better in my opinion and will reduce the amount of sand you need to remove. A common height is 140mm (common width of composite decking for example) which means you'll only need to clear 60-110mm.

dazezy

https://www.workshop.bunnings.com.au/discussion/comment/141272#Comment_141272

Thanks for the reply. Yeah we removed about half of the sand today, hopefully the rest tomorrow. We are planning to step off the liquid limestone onto the deck. 140 seems like a decent step
Hey a question about the posts, just so my maths is correct.
Atleast 300mm in ground + clearance (say approx 200mm) + 140mm bearer.
So my post will be approx 640mm with 300mm in ground?

ProjectPete

https://www.workshop.bunnings.com.au/discussion/comment/142745#Comment_142745

@dazezy Base it on those measurements and you won't run short when ordering materials. Measure/cut once the hole is dug though to confirm.

dazezy

https://www.workshop.bunnings.com.au/discussion/comment/143790#Comment_143790

@ProjectPete

Thanks mate. Away at work at the moment. Hoping to start the deck in 2 weeks time. A couple of questions if you have the time.
Based on the previous question about the posts, that would mean less than 50% of the post is in the ground. Just wanted to make sure in your opinion that isn’t a concern.
Also in regards to securing the boards to the frame. What’s your preference.
* Hidden clip system like the screwfix from Ekodeck
* Decking Screws
* Camo/Kreg fastener system.

Thanks again for your time replying 👍🏻

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