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How to build a low-level deck on pavers?

simont

Hello all,

I'm planning to build a deck on pavers. Here are some details (also see photo).

- Deck will be outdoor, uncovered.

- Size approximately 4.0m x 3.6m

- Thinking of joist spacing ~450mm

- Merbau decking

- Pavers seems stable, however, some areas are uneven.

- Clearance (pavers to house floor level) ~110mm

Some help/questions per below:

- What joist size to use? Is H3 70x45 suitable?

- What footings to use? Is Builders Edge 25-40mm Minifoot Pedestal Feet suitable?

- This should bring the total height: 25 (footing) + 70 (joist) + 19 (deck) = 114mm. Will this cause any issues with ventilation and drainage?

- Will I be better off by building the subframe from scratch (using H3 timber + pedestal feet) OR by using the Good Times module base frame 70x45?

- Can the deck cover the drain?

Thanks for your help!

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Comments

Akanksha

A warm welcome to the Bunnings Workshop community, @simont. We're delighted to have you join us and trust you'll find this site a handy resource containing useful advice and inspiring ideas for all your D.I.Y. projects.

Thanks for your question on building a low-level deck. Our resident Bunnings D.I.Y. expert @EricL will be online later today and will be happy to assist. Also tagging @LePallet, @hadi, @ProjectPete and @tom_builds to see if they have any thoughts in the meantime.

While waiting, I recommend having a look experienced renovator @Adam_W's guide How to build a low-level deck for pointers on how to get started. You can also check out the Top 10 most popular low-level deck projects shared on Workshop for inspiration.

Please do keep us updated as your project progresses. I'd love to see the final result.

Akanksha

EricL

Hello @simont

If you were to remove the material thickness of the frame H3 70x35 and decking panel 19mm from your available space of 110mm you would be technically left with 21mm. This means that you won't be able to put in the mini foot pedestal to support your decking frame.

The available options are to remove the pavers so that you have more space for footing, use 20 mm pavers over the existing pavers, attach angle brackets if the old pavers are thick enough to anchor on and of course use traditional H4 treated timber posts as footing.

Building the decking frame from scratch gives you absolute control and will allow you to max out on the space available. Using the pre-made kit means that it will be limited to how you'll be able to size it.

If you need further assistance, please let us know.

Eric

simont

https://www.workshop.bunnings.com.au/discussion/comment/32168#Comment_32168

Thanks @EricL for your reply.

With the second option you mention "...use 20 mm pavers over the existing pavers", do you mean adding a 20mm thick paver on top of the existing paver with the joist resting on top of it directly? If so, at what intervals should there be a support for the joist? Also, can I use plastic shims or builder's wedge in lieu of 20mm paver?

With this arrangement will it cause any issues ventilation and drainage?

Can the deck cover the drain?

Thank you.

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/78528#Comment_78528

Hi @simont,

That's correct, 20mm pavers on top of the existing pavers and then the joist resting on top. You can use wedges and shims instead, but you'd need to add noggins to stabilise the joists; the frame might not be enough.

A 70 x 45mm joist should be supported around every 750mm. It could be supported less frequently, but at 750mm, it ensures the deck will not become bouncy.

Creating a low-level deck always creates ventilation issues. The lower you go, the worse they are. Creating a low-level deck within 110mm isn't the lowest I've seen, and only time will tell whether you'll see an early onset of decay due to the minimal height. Ten years ago, decks at this height were not being constructed as the opinion was that their lifespan would be very short. Time has shown us that that's not necessarily the case, and low-level decks have become the norm.

You can create the deck over the drain; just be aware that you'll need to access it at some stage to clear out debris, and having a solid deck over it would create an issue. If you can, try to design your joists so a couple of decking boards can be removed periodically to gain access to the drain grate.

Please let me know if you have any questions.

Mitchell

simont

https://www.workshop.bunnings.com.au/discussion/comment/103465#Comment_103465

Hi all,

I'm also building another deck where there's sufficient height to use the pedestal footing system.

I'm planning to use a combination of Builders Edge 35 - 60mm Smallfoot Pedestal Feet and Builders Edge 70 - 170mm Bigfoot Xl Pedestal Feet to support the joists. Am also planning 'picture frame' the deck.

Some questions:

- As the pedestal feet base is wider than the joist width, how do you design/position the pedestal support for outer most joist, such that the feet is not visible and does not hinder the installation of the deck fascia boards? (see photo)

- Regarding noggings , how frequent/at what intervals should a nogging be installed between joists?

- What product would you recommend the cover the joists with to prevent water pooling/rotting of the joists?

- Some of the area underneath will be ground, how do I prepare the area? Should I lay a plastic membrane, followed by gravel and then the pedestal on top of the gravel, in that order? What plastic membrane should I be using?

EricL

https://www.workshop.bunnings.com.au/discussion/comment/118773#Comment_118773

Hello @simont

I suggest having a quick look at this featured project - Low-level composite deck over concrete and soil by @oninpena. This is a good example of a single level decking frame using pedestal feet.

In regards to the fascia boards, I suggest adding another joist and screwing the two lengths of timber together and place the pedestal footing on the interior side of the frame.
Depending on the length of the deck you I suggest positioning the nogging every 1 meter, but this can be shortened if the deck is not very long. Please remember to offset the nogging when installing the next section beside it. Just keep in mind that the more nogging you have the stiffer the deck frame will be.
I suggest using CAgroup 50mm x 20m Bearer Protector G-Tape. Use it on the entire top section of your decking frame.
For those areas that will be on the ground please make sure that the fall of the soil is away from your fence and away from the deck. I recommend compacting the soil before you put anything on top. I suggest placing weed mat down. You then place a paver on top of the weed mat and surround the area with gravel.
Placing the paver on top of the gravel is not recommended as you will not get a flat surface and could cause it to settle at a strange angle.

If you need further assistance, please let us know.

Eric

simont

https://www.workshop.bunnings.com.au/discussion/comment/127886#Comment_127886

Thank you all for your help and advice thus far.

I've removed the old deck, and noticed some pavers (which was under the old deck have been lifted up by tree roots). As such I've removed that section of the pavers to get to the roots. As this section will be covered by the new deck, I do not intend on putting the pavers back (it's a pain to re-lay the old pavers).

For drainage purpose ensuring the fall is towards the drain grate, I'm thinking of filling back up the area (outline in dotted red) as there's a ~40mm gap from the removed pavers. Then compact it ensuring top of the fill is flushed with the existing paver level, and cover it with weed mat. Then only place the paver/pedestal feet on top of the weed mat and surround the are with gravel.

Seeking some advice:

- is the above plan/sequence of steps the right way to go about?

- what should I fill the area with (which is the most economical and suitable for the job)? crushed rocks, paving sand, etc?

Thank you.

snippet 3.JPG

EricL

https://www.workshop.bunnings.com.au/discussion/comment/133847#Comment_133847

Hi @simont

Thank you very much for the update. Your proposed list of sequence of events looks good. I suggest using Bastion 20kg Aggregate Crusher Dust to get good drainage even when compacted in place. Once you achieve the level you are after you can then continue with your proposed list of steps.

If you need further assistance, please let us know.

Eric

simont

https://www.workshop.bunnings.com.au/discussion/comment/137533#Comment_137533

Thanks @EricL.

Sorry to ask, do you have a link to the "builders mix' product? Just want to be clear on it 🙂

Thank you!

EricL

https://www.workshop.bunnings.com.au/discussion/comment/140060#Comment_140060

Hi @simont

My apologies for the incorrect reference, I meant to say Bastion 20kg Aggregate Crusher Dust. Builders mix is actually a concrete mix which is something you're not supposed to use for your project.

Eric

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