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How to build a low-level deck next to a pool?

Hi all, these forums have been very helpful in planning my poolside deck. I have a few questions from the experts which I havn't been able to find yet though before I submit my plans.

I am planning on building a deck alongside this pool.

The ground slopes gradually away towards the pool filter, so I originally planned a combination of bearers on stirrups and posts on stirrups. After consulting span tables I have landed on 175*75mm F14 bearers and 100*50mm F14 joists. Plan to use SS joist hangers and screws. Noggins arent on the plans, but will incorporate.

Here are my plans so far:

Screenshot 2025-02-14 163542.png Screenshot 2025-02-14 163528.png Screenshot 2025-02-14 163502.png Screenshot 2025-02-14 163356.png

Screenshot 2025-02-14 164727.png

Here are my main questions:

**Does anyone see anything obviously incorrect about this design? I have consulted the forums and Allan Staines' manual and will use for fixings and joints. There are no site drainage issues, just pool water splashing.

**I would have prefered to use stainless steel post supports given deck is poolside. 75mm isnt available, so that would involve levelling the ground to allow enough room for a stirrup and post on the high side. Is that worth it, it will mean the site doesn't drain as freely as currently. Is Gal sufficient? It is a mineral rather than salt pool.

**Am I overthinking this and should I just mount H4/H5 posts into the ground and be done with it?

**What life expectancy am I gaining by using stirrups and hardwood rather than posts in the ground and potentially pine bearers and joists?

**I was planning on joining the bearers with a half lap joint and a nail plate on the side. I assume the best place for this is above the post, but this will block a nail plate on one side. Should the join be somewhere else?

Thanks all for you help in advance

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Comments

JacobZ

Hi @alexanderCa,

A warm welcome to the Bunnings Workshop community and thank you for your question.

You've already got a nice solid plan in place; however, you should check the allowable spans for the joists as the span tables I've found show 100x50 F14 Hardwood is not capable of spanning 2 metres between bearers. You will need to size up to 125x50mm F14 Hardwood, which is capable of spanning 2.3 metres between bearers.

Stainless steel hardware should definitely be used where possible as it is much better at resisting the corrosive effects that are present around pools. You can always use a larger stirrup such as this VUEPRO 300 X 90mm Stainless Steel Full Stirrup Post Support and add packers inside the stirrup before bolting it in place.

I couldn't tell you an exact figure for how much life expectancy you are gaining, but stainless steel is the most durable material in an application such as this, so it is worthwhile using it.

I prefer keeping the in-ground contact of timber and concrete to a minimum, but if you'd be more comfortable using an H4/H5 post, it would be worthwhile coating it in a bitumen membrane to help prevent decay from the wet conditions.

Your half-lap joins should be located directly over a stirrup. Using a stainless-steel nail plate alongside screws through the top and bottom of the joint will create a nice solid connection. If you are using a 90mm stirrup, then there will be plenty of clearance for this nail plate.

All in all, you have a solid plan that I'm excited to see come to life.

Allow me to tag @Dave-1, @TedBear and @Nailbag to see if they have any thoughts.

Let me know if you have any further questions.

Jacob

Nailbag

Hi @alexanderCa

Super impressive set of plans there. @JacobZ has covered off all your questions just as impressively. The only thing I would add is the use of Protecadeck strips on the joists. And to consider by sub-floor stage and requirements for running low voltage lighting cable. A very long time ago when I had a pool with a surrounding deck I built, I also added tubes to drop in umbrellas for both deck seating or pool edge shade for the kids.

Nailbag

alexanderCa

https://www.workshop.bunnings.com.au/discussion/comment/48810#Comment_48810

Thanks Jacob. I must be misinterpreting this table. I will up the joist size. I have decided to move to 90mm posts which will work with the strirrups you have linked and dig out the depth as required.

Cheers

alexanderCa

https://www.workshop.bunnings.com.au/discussion/comment/48823#Comment_48823

Thanks, good tip. I was also planning on painting the stirrups and bearers with outdoor paint as they will not be able to be seen anyway.

Cheers

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/86503#Comment_86503

Evening @alexanderCa

Nice plans 🙂 And @JacobZ and yourself have already sorted the only thing I saw an issue with (the span between posts)

I have stirrups for my poolside deck and they are on slopped ground. They are gal and go into the ground 600mm ish

Pool deck stage 1 is the project. Its still standing solid as after 11 odd years 🙂 Just did a bit of maintenece on it this last year (sanding/oiling and re-oiling)

I like @Nailbag's suggestion of the low voltage lighting, id also up the anyi and consider a power point somewhere (away from the pool ) You probarly have an outside powerpoint/gpo for the pump so it may be easier then you expect to put another one in for parties ect.

Looking forward to seeing the deck 🙂

Dave

JacobZ

https://www.workshop.bunnings.com.au/discussion/comment/86503#Comment_86503

Hi @alexanderCa,

The information I could find on spans for F17 Hardwood was very limited and you're interpreting your span tables correctly, so it is likely fine to use seasoned 100x50 F17 hardwood for your joists.

If you wanted to be absolutely certain your deck was strong, then it would be worthwhile bumping up the size of the joists, but based on your span tables, it is likely not necessary.

I'm very excited to see your project get under way, so please keep us in the loop as things commence.

Jacob

alexanderCa

https://www.workshop.bunnings.com.au/discussion/comment/48823#Comment_48823

Both good ideas. Did you mount tubes on the joists or set in a footer?

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/86588#Comment_86588

Evening @alexanderCa

I just went back and looked to see if the stirrup post showed the base in the project... lol for someone that takes a LOT of photos I still manage to miss the important ones 🙂 My ownly excuse is it was from 2011 but still I should have shown the material I used for future reference 🙂

So the stirrups had a flat square edge to the base, they were 600mm long and I hung them using the timber and G clamps above the concrete in line with each other. That way I knew the base wasnt touching the soil and also they were firmily encased in concrete.

Step two of the project I linked showed the admittidly different way I was supporting them but that was all the timber I had at that point. 🙂

Dave

alexanderCa

Providing a status update on my project. After lenghtly delays due to other committments, work has begun. Footer holes were dug this week. Was aiming for 60cm deep and 40cm wide. Trenching and regular shovel were fine for getting it done. No auger needed, especially with all the rain we have been having. Groundwater found its way into the holes to varying degrees.

I decided to run bearers on stirrups and raise the level of the footers where necessary to level off the deck. A mix of very short / no posts felt excessive.

Next step was stringline marking out where the stirrups will go. I wish I bought/hired a beep laser for this. The Dewalt 360 really struggled in the daylight. 4 string lines took an unreasonably long period of time, but I am pretty confident its square and level now.

After getting ready for formwork today, it of course poured rain last night, filling the holes completely and turning the site into a mud pit.

Still, no reason not to proceceed. Pumped out the holes and formed up the stirrups and bottomless buckets which I am using to raise the footers above ground level where necessary. Next step is concrete taxi. Following that I plan on reworking the drainage here, grading back to a level slope and covering the area with aggregate.

JacobZ

https://www.workshop.bunnings.com.au/discussion/comment/51875#Comment_51875

Hi @alexanderCa,

It always seems to be the way that the clear skies disappear shortly after you've dug holes for concrete footings. Having bailed water out of quite a few footing holes over my time, I feel your pain.

I like the idea of using a bottomless bucket as a formwork to raise your footing that little bit above the ground. It's a pretty ingenious solution to tell you the truth. Nice work.

Your set out looks good and I'm sure you've set yourself up for success as you move into the construction of your frame.

Awesome work so far. I can't wait to see your deck progress.

Jacob

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/88081#Comment_88081

Good Evening @alexanderCa

Have to agree with @JacobZ , thats a nifty idea with the bottomless bucket to raise the footing a bit 🙂 Wish I had thought of it years ago!

Looks good and yep, all my holes filled up with water serveral times as I was digging it. Kinda like washing your car, you just know its going to rain:)

Cant wait to see you continue along the project 🙂

Dave

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