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How to build a deck for an outdoor barrel sauna?

Good evening team!

I have purchased an outdoor barrel sauna (assembling that thing is going to be a post in itself!) and I need to build a deck to support it.

Some basic information:

1. Sauna weighs 400kg without humans in it.

2. Is 191cm wide and 224cm long/deep.

3. I would like to match this with the current decking in place which is an engineered wood.

4. The deck would kinda be nudging an easement, so perhaps floating is needed?

The Area

This is the garden bed up against the fence. It used to have this weird lean to structure that housed a bunch of shade plants. You can see the bed sits a little above the current deck, and I'm happy for the proposed deck to sit a 'step up' above the current deck. Note, I will be relocating that hose/tap currently in place.

The Current Decking Material

Would be ideal to match to the current decking material.

The Space and The Sauna

Here are the dimensions of the garden bed, with the sauna overlayed (blue). For aesthetics, I would prefer to have the sauna in the center of this space, so I'm guessing the deck will need to jut out a little and sit on top/hang over the current deck. The proposed deck doesn't have to take up this entire area, but I think some space either side of the sauna would be great to place some potted plants, and an outdoor shower. Size would be also dictated by whatever I can build in Victoria without a permit.

Dimensions of garden bed and sauna overlayed

Any advice on design, materials, considerations/options would be amazing.

Thanks

Rod

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Comments

EricL

Hello @RMac (Rod)

Welcome to the Bunnings Workshop community. It's a pleasure to have you join us, and thank you for sharing your questions about building a deck for your Outdoor Barrel Sauna.

Thanks for sharing photos and measurements of the area. I had a quick look at the Outdoor Barrel Sauna models and you're absolutely correct those things are massive. It will definitely need a post for itself when you assemble it. To help us get started, would it be possible for you to post the name and model number of the sauna so that we can do some sketches of how it's going to look once it's assembled and installed?

Eric

RMac

https://www.workshop.bunnings.com.au/discussion/comment/22560#Comment_22560

Thanks Eric!

https://alpinespas.com.au/shop/barrel-sauna/

this is the model I have purchased.

Remarka6le

Following as a general interest, would love to see what you two come up with. I previously wanted a Barrel Sauna for our backyard before I discovered ones I can install inside (such as The Oslo), the things are massive and it's unreal they come in kits!

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/73981#Comment_73981

Hi @RMac,

Your deck must adhere to standard weight-bearing requirements and then have the capacity to hold the additional weight of the sauna. Here's a rendering I threw together of what a standard deck of this size might look like. The frame and joists could be constructed of 90 x 45mm timber, and the deck would be adequate for normal use.

For a deck that will support a sauna's weight and the occupant's, you'd need to at least double up on everything. I'd suggest using 140 x 45mm timber and laminating two together for each joist. Ideally, you'd like the feet to be sitting directly above a supported joist where the weight of it transfers straight down to the ground. This might be overkill, but it's hard to tell unless you have an engineer design the plans. Here are a few renders to give you an idea of what that might look like. Any additional deck space outside the sauna's footprint can be constructed of light calibre timber to cut costs.

Before constructing the deck, you'll need to carefully prepare the area to avoid subsidence issues. I'd recommend removing soil from the garden bed until you are at least level with the current deck, if not lower. I'd prefer at least 100mm lower as you'll need to run over the area with a compactor and add some height back to the area with drainage gravel.

Before starting construction, I'd suggest contacting your local council to enquire about the requirements for such a build. The deck sounds like it wouldn't need approval, but you'd want to make sure that by putting the sauna on it, it doesn't put it into another category where it does. They'll also be able to let you know the max square meterage before you need to apply for approval.

Please let us know if you have any questions.

Mitchell

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/100493#Comment_100493

Hi Rod (@RMac),

Eric and I were chatting about your project and wanted to know whether you'd considered turning the sauna side on and placing it in the top left-hand side of the yard. You could level the area and pour a slab for it to sit on. That way, you wouldn't have to construct a heavy-duty deck and instead could create a standard deck and include perhaps a decking-clad bench seat for when you're coming in and out of the sauna.

Instead of walking straight up and into the sauna, you'd step onto the deck and turn left to enter the door. If you were to plant bamboo along the side of the sauna to conceal it, it could look stunning. We also noticed that the sauna itself was elevated on the feet. So if you're going to have the front of it right on the edge of the new deck, there's quite a high step up onto it.

Mitchell

RMac

https://www.workshop.bunnings.com.au/discussion/comment/117123#Comment_117123

Hey Mitchell,

That deck is looking pretty complicated! Aesthetically I do have my heart set on having the sauna face forward. I have measured out having the sauna around the center line, and it does fit with a little tolerance of the current deck.

The slab seems like a good option, however I'm wondering what your thoughts are on building a compressed rock/gravel bed for it to sit on? Im assuming we could place the feet of the sauna on dug in blocks (or equivalent). Whatever makes it the least likely to shift. I think this would look much more organic and we have a ridiculously tree/garden filled block.

See below for inspiration. Is it possible to dig down, build a bed of crushed rock (I'm guessing in a frame), to a level so that the sauna entry is the same height as the current deck?

EricL

https://www.workshop.bunnings.com.au/discussion/comment/126704#Comment_126704

Hi Rod (@RMac)

I was thinking along the same lines where you could build a concrete pad and then cover it with gravel to disguise it. The outside of course would be clad in timber to disguise it and make people think it's made out of timber. Rather than bringing the sauna to the deck why not bring the deck to the sauna? I suggest building the deck below to the same height as the first step of the sauna. In this manner, there are fewer tripping hazards as you approach and enter the sauna.

Eric

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/126704#Comment_126704

Sorry, Rod (@RMac). I should have been more specific. The concrete pad is just for a solid base; you'd be covering that with a more aesthetically pleasing topping like crushed granite. A compacted bed of roadbase, which is then topped with crushed rock enclosed by a frame, would also work. However, you'd need an area of soil that could accommodate the sauna's footprint. When you mentioned that you've "measured out having the sauna around the centre line, and it does fit with a little tolerance of the current deck.", does that mean that in your preferred location, you could fit it without overhanging the deck? If so, fantastic.

Deck's are typically designed to hold the weight of people and a few additional items like BBQs and table settings. With an additional 400 kg on the deck, it will become pretty complicated. That's why I'd prefer to lay it on a compacted base. Not only would that save a heap of money which could be spent on accessorising the area, but it's a more solid solution.

Your inspiration pictures look great and are similar to what I'd envisaged. My only concern with digging down is how close it will be to the rear fence line. You might need to add an additional treated Pine slab to the bottom of the fence posts to ensure you don't undermine the property next door.

Mitchell

EricL

https://www.workshop.bunnings.com.au/discussion/comment/126704#Comment_126704

Hi Rod (@RMac)

I've drawn up some basic sketches with the measurements you've indicated. Please note that the deck I've drawn up is not included in your measurements, but you can clearly see that the sauna takes up a great deal of space. I suggest getting some string line or a spray marker so you can outline the size of the barrel sauna. This will give you a much better idea of the space the sauna will occupy thus giving you an approximation of what you can put around it.

Have a good look and if you want items moved around please let me know.

Eric

Rods Deck and Sauna1.jpg Rods Deck and Sauna2.jpg Rods Deck and Sauna3.jpg

RMac

https://www.workshop.bunnings.com.au/discussion/comment/133092#Comment_133092

Hey Mitchell and Eric,

Well its been a weekend of digging out a massive amount of soil to level the area! Love the ideas above. Whilst I would love to do a concrete slab, I do plan on moving the sauna in the longer term, say 3-5 years when we complete further landscaping in our backyard (still have pool dreams!). Great idea on string line, I will get this measured up and post some photos of what we are working with.

For building a compacted base, with framework, do you have any guides or instructions to complete? For example:

- depth of framework

- recommended timber to build framework

- how much roadbase to use, and to what depth

- do you need to use sand

- must do tips and advice to limit any settling

Also super noob question @MitchellMc, what do you recommend for the timber to reinforce the fence? Where to connect the timber slab?

Cheers
Rod

MitchellMc

Hi Rod (@RMac),

I've had a read through the installation instructions to see if there is any specific requirement for the compacted base. All I could find was "Ensure the foundation is level and can withstand the weight of the barrel sauna without subsiding.". Since there are no specific requirements and some suppliers suggest that you don't need a compacted base at all, then I'd suggest constructing a base with good drainage that isn't overly deep.

The following should assist:

Remove 50mm of soil from your desired finish height and level the area using a string line and line level. Since you're planning on using a string line to mark the site, you can use this as your reference point. Once you have your level perimeter line, measure down to check your depth and that the excavated area is also level.

Around the perimeter of the area, dig a 50mm wide trench that is 150mm deep. Digging it slightly wider is OK, as you'll be backfilling later. The depth is the main requirement.

Insert 200 x 50mm sleepers into the trench and connect them with 450mm Sleeper Peg Steel Corner Stake Heavy Duty and 450mm Sleeper Peg Steel Flat Stake Heavy Duty if you need to extend lengths. Backfill your trench. This will leave your sleeper border 50mm above ground level. If you'd like to avoid this lip and are aiming for a flush transition from stones to the surrounding soil, then instead dig your trench to a depth of 200mm.

To ensure you don't experience any subsidence issues in the future, I'd suggest running over the soil to ensure it's compacted and level. You can hire a compactor for 4 hours, which should be plenty of time for this small area.

Lay Geo-Textile fabric over the area to aid drainage and prevent weeds from growing up from the soil and through your pebbles.

To fill the area, you could do a 30mm layer of sand and compact it before filling the remaining height with your crushed rock. Or, just fill the 50mm with your crushed rock. I've seen this model sauna placed on un-compacted soil, so the additional sand and compaction layer might not be necessary. For your medium, the larger the stone size, the better the drainage quality. I'd encourage you to check out our range of bulk-delivered products as they'll work out far more budget-friendly than smaller bags. We can also order feature boulders and larger rocks for landscaping around the sauna through our supplier, ANL.

If you start to undermine the fence, you can affix a treated pine sleeper between the two upright posts with Climacoat Bugle Screws. This additional sleeper would be placed directly below the current one.

Please let me know if you have any questions.

Mitchell

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