How to build a deck for an outdoor barrel sauna?

[RMac]

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

[RMac]

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