ᐅ Building a Sauna Yourself with a Sloped Ceiling – Suggestions, Tips, and Planning Advice

Created on: 24 Nov 2020 10:14
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matte
Hello! [IMG alt=" 🙂"]https://saunabauen.de/forum/images/smilies/icon_smile.gif[/IMG]

I’d like to start this thread to get help and feedback on my plan to build a sauna myself. Of course, this thread can also be used for any topics related to sauna construction.

We decided to get a sauna, and since a prefabricated kit was not an option and a custom build was too expensive, I decided to take matters into my own hands.

When we built our house three years ago, we reserved space for a sauna at the top near the roof terrace. Unfortunately, instead of a planned flat roof, we had to install a sloped roof to get the building permit / planning permission.
This results in a roof slope with knee wall height of 1.81m (5 ft 11 in) clear height.
There is a floor area of 2.10m (83 inches) wide and 1.91m (75 inches) deep available.

The height is additionally limited by a fresh air vent on the higher side. The bottom edge of the vent is located at 2.05m (6 ft 9 in) above the finished floor level.
My idea is to build the sauna ceiling at 2.05m (6 ft 9 in) height to still be able to access this vent if necessary. According to my plan, the clear interior height inside the sauna would then be about 1.995m (6 ft 6.5 in).

The sauna will be surrounded on three sides by exterior walls (Poroton T9 masonry).

The ceiling is attached directly to the beams and vapor barrier, without counter battens. This was necessary because otherwise the terrace door would not be able to open. The architect missed that... : [IMG alt=":roll:"]https://saunabauen.de/forum/images/smilies/icon_rolleyes.gif[/IMG]
The floor is fine stoneware tiles on a screed layer with underfloor heating.

We have a three-phase power supply with 5x2.5mm² cable and a cable length of about 20m (66 ft). According to an electrician, this line should not restrict the project.

Since space is quite tight, I want to keep the wall construction as thin as possible.

Planned wall build-up:
1. Masonry with plaster
2. Vertical battens (24x48mm / 1x2 inches) with 24mm (1 inch) air gap for ventilation
3. OSB boards 15mm (0.6 inch)
4. KVH timber beams 40x60mm (1.5x2.5 inches), positioned so the 40mm (1.5 inch) side accommodates insulation
5. 40mm (1.5 inch) wood fiber insulation inside
6. No vapor barrier
7. 15mm (0.6 inch) profiled battens mounted horizontally

Now my questions:

1. Is my wall build-up feasible, or am I trying to save too much space? This would leave an interior floor dimension of nearly 1.92m x 1.75m (6 ft 3.5 in x 5 ft 9 in).
I’m 1.84m (6 ft 0.5 in) tall, so I should still have enough room to lie down comfortably.

2. We want to install a full glass door with a side panel to enjoy the outdoor view.
We plan to use 8mm (0.3 inch) tempered safety glass (ESG). Is that okay, or can this cause issues near the heater?

3. How do you connect the glass wall to the sauna structure? I thought about routing a groove around the KVH timber to set the glass in. Is that a good approach?
For the floor, I read that someone placed the glass on a silicone mat which was then trimmed flush. That sounds like a good solution to me.

3. The sauna floor area is 3.34m² (36 ft²) with an interior height of 1.995m (6 ft 6.5 in). Ignoring the slope, that gives a volume of 6.66m³ (235 ft³).
I read that for a glass door you add 1.5m³ (53 ft³) and for a glass wall the area (1.5m² / 16 ft²) multiplied by 1.2 as additional volume.
So, I’d end up with a total volume of 9.66m³ (341 ft³) and chose a 9kW heater accordingly. Does that sound right or oversized? I’m currently leaning towards the "Harvia The Wall" with external control.

4. Due to the heater’s position, there is essentially no room for a heater guard between the glass wall and heater. Is a guard necessary in a private sauna? I’m not too worried about it, but my wife is concerned.
The alternative would be to shift the lower bench slightly under the upper bench and move the heater, which would create space for a guard.
Alternatively, there is a glass protective shield with integrated lighting available that mounts in front of the heater. Would that be enough? I’m not too keen on wooden guards though... [IMG alt=";)"]https://saunabauen.de/forum/images/smilies/icon_wink.gif[/IMG]

5. A coworker recommended bench heights of 60cm and 120cm (24 and 47 inches). That would cause problems with the sauna height. I was thinking about 45cm and 90cm (18 and 35 inches) instead. Since we don’t want it very hot anyway, I see no reason for higher benches.

6. To avoid further reducing the roof slope height, I considered skipping the OSB boards there and mounting the KVH beams directly at a 24mm (1 inch) gap (batten distance) from the ceiling. Any issues with that?

7. We prefer the look of horizontally mounted profiled battens. Any objections? Given the tight space, I would skip additional rear ventilation. From what I’ve read, that’s not strictly necessary.

8. In my case, would it be better to use a different insulation material with a vapor barrier instead of wood fiber insulation?

9. The left wall with the glass door will be clad on the outside with profiled wood boards as well. This way I could install an access panel above the sauna to reach the fresh air vent if needed. Also, I could place the electronics for lighting and audio on the ceiling, making them accessible.
Can I mount the cladding boards directly on the KVH beams, or is an additional counter batten or similar required?
I want the wall to finish flush with the terrace door frame. To prevent the terrace door (especially the handle) from hitting the wall, I plan to install a stopper mounted on the KVH timber there.

That’s it for now. I’m curious what you think about my plan. I hope my post is not too long... [IMG alt=":?"]https://saunabauen.de/forum/images/smilies/icon_confused.gif[/IMG]

I’m attaching some pictures to show the current planning status. If you need more info, just ask.

Looking forward to any feedback [IMG alt=";)"]https://saunabauen.de/forum/images/smilies/icon_wink.gif[/IMG]

Thanks in advance!

Best regards

Loft room with staircase, wooden cabinet, books, window on the right; bright and tidy.


Floor plan of a sauna room with heater, wooden bench, door, insulation, and dimensions


Cross section of a sauna with glass door, seating benches, Harvia 9 kW heater, and dimensions.


Small storage room with pink cabinets/shelves in front of a brick wall, gray door on the right.


3D rendering of an open elevator with glass front in front of a brick wall, pink interior walls and shelves.


3D model: interior with green-blue steel beams over brown floor panels, brick wall on the right.
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pagoni2020
3 Mar 2021 11:49
It was the same with my sauna back then; in the end, the costs do add up.
The great thing about building it yourself is that you only have to deal with yourself, and it’s also enjoyable to successfully complete your own project.
I’m still quite far from my outdoor sauna, since right now only the base slab is being prepared. We’ll see what it turns out to be—self-built or maybe I’ll find a suitable outdoor sauna supplier for a spoiled consumer like me.
Schimi17913 Mar 2021 12:30
pagoni2020 schrieb:

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I’m still quite far from having my outdoor sauna, as the foundation slab is only being prepared at the moment.
...
At least I have already chosen the spot for it in my garden 🙂
pagoni2020 schrieb:

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I still need to find a suitable outdoor sauna supplier for me, a rather demanding customer.

I pass by my supplier almost every day… 😳 🙁
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pagoni2020
3 Mar 2021 12:35
Schimi1791 schrieb:

I have already chosen the space for it in the garden 🙂
Same here... it will be integrated at the back of the carport
Schimi1791 schrieb:

I pass by my supplier almost every day...
...which would be.... 🤨 🤨??
Schimi17913 Mar 2021 12:43
pagoni2020 schrieb:

...
...what would that be.... 🤨 🤨??
For me, it’s a small local craftsman company with a very good reputation. They work, among others, with Viliv Saunawerk. But first, I would have to prepare our slope and install (or have installed) the foundation slab. I estimate the project to cost around 15,000€ (about 16,200 USD). I don’t have any quotes yet. There will definitely be a dedicated thread for that later. It would certainly be cheaper if you just convert an appropriate garden shed. I might be able to tackle that with my neighbor.

Overall, I need to think about how to make our slope easier to maintain. I’ll bring this up soon in the “garden thread.” Maybe by then, the future location for the sauna can at least be prepared.
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matte
3 Mar 2021 13:21
pagoni2020 schrieb:

When I built my sauna back then, it was the same—small costs add up in the end.
The great thing about DIY is that you only have to deal with yourself, and it’s also fun to successfully complete your own project.
I’m still quite a way from my outdoor sauna, as the foundation slab is only being prepared right now. Let’s see what it will be in the end—DIY or maybe I’ll find a suitable outdoor sauna supplier for a consumer spoiled like me.

True words.

Honestly, the only real savings I could have made were with the electrical work—lighting, controls, and the heater.
Instead of a combination heater, a regular one with analog controls, plus a simple corner light inside the cabin, would probably have made the sauna about 1000€ cheaper.
There’s not much room to save on the wood. Spruce as profile wood is already one of the most affordable choices. You could have saved 100–200€ by using different bench slats (meaning without rounded edges and narrower slats).

Originally, I wanted to keep it under 4000€ (about $4300), which didn’t quite work out, but now it’s exactly how I wanted it. The sauna builder initially quoted me a price starting around 12,000 to 14,000€ (approximately $13,000–15,000).
With a combination heater and fancy lighting, I would expect something closer to 16,000 to 18,000€ (about $17,000–19,000). So that’s about four times the cost. But it’s self-made, and I really enjoyed the process. 🙂

I’m almost a bit sad it’s finished. My wife has already lined up the next projects with a sandbox and tax declarations for 2019 and 2020, but somehow I’m not motivated for those yet. 😀
Schimi17913 Mar 2021 13:28
matte1987 schrieb:

...
My wife came up with the idea of a sandbox
...
Yes... yes... women! 😉

Some of my male friends who are more skilled with DIY projects have also told me about certain wishlists from their wives. Good thing I only have basic expandable knowledge in craftsmanship...

But it’s really great to be able—and willing—to make something like that happen!

Currently, my wife’s wishlist only includes the disposal of green waste. Oh, and an outdoor kitchen 😎 🙄
matte1987 schrieb:

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With a combination oven and that kind of lighting, I’m more in the range of about €16,000–18,000.
....
😱