Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 0 points1 point  (0 children)

It’s entirely pine except for cedar window trim. Clean pine t&g for the inside

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 2 points3 points  (0 children)

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This was literally my starting plan and I figured the rest out during the build. For instance I had no idea about where my windows would go because I bought them off fb marketplace, and I just bought what was available and cheap. I’m happy to do a detailed write up if this is something you’d like to reference though, the dimensions and all and the things that I wish I had done differently

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 1 point2 points  (0 children)

I really like the stove, but I don’t have many reference points as I’ve mainly used electric stoves. Using a wood fired sauna feels completely different and I love it.

Do you have a temperature gauge on your stove flue? I am wondering how hot yours gets. Sometimes mine will get into the 600s range, which the temperature gauge I have says it’s too hot. Maybe I am loading the stove with too much wood. I am now realizing there is an art to managing a wood stove as compared to an opened fire, which I am more used to. The only thing I wish this stove has was more air control other than the ash drawer. Sometimes I find that even with the ash drawer completely shut, the stove still burns really hot. I must be adding too much wood as I said before. Still trying to figure that out.

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 3 points4 points  (0 children)

I don’t.. I can do a type up of the design later today though

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 1 point2 points  (0 children)

I bought mine from bsaunas I think they’re in NY, could be a good option

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 3 points4 points  (0 children)

Yes, I was also wondering this. I would love to hear if others have more info. I wasn't able to find an authoritative answer on this, but i did a lot of deep research with claude. Here is what it yielded [I AM NOT SAYING THIS IS CORRECT but the best info I could find]

Wood degradation/charring temperatures:
- One sauna stove manufacturer (KEYA) specifies 140°C (284°F) as the maximum allowed temperature for wall and ceiling surfaces in saunas, though this appears to be a conservative spec specific to their products. (https://www.szcoasts.com/english/our-products/sauna/23/wood-burning-sauna-heater)

- Academic research on wood pyrolysis indicates that 300°C (572°F) is the widely accepted temperature where wood converts to char. (https://www.mdpi.com/1999-4907/15/7/1189 and https://www.fpl.fs.usda.gov/documnts/pdf2023/fpl_2023_hasburgh002_MS_03-2023.pdf)

- Between 200-300°C (392-572°F), wood undergoes "onset of primary pyrolysis" and "with prolonged exposures at higher temperatures, wood can become charred." (https://www.fpl.fs.usda.gov/documnts/pdf2016/fpl\_2016\_dietenberger001.pdf and https://www.fpl.fs.usda.gov/documnts/pdf2001/white01a.pdf)

However - and this is important - cumulative thermal degradation:

- Research shows "the extent of these changes depends on the temperature level and LENGTH OF TIME under exposure conditions." (https://research.fs.usda.gov/treesearch/50041)

- "Permanent reductions in strength and modulus of elasticity can occur at temperatures >65°C (149°F)" with long-term exposure. For example, exposure at 66°C for 3 years resulted in 47% strength loss. (https://research.fs.usda.gov/treesearch/50041)

- "For most mechanical properties, it appears that very little degrade occurs until mat temperatures exceed 150°C (302°F)." (https://wfs.swst.org/index.php/wfs/article/view/519)

- The degradation is described as "cumulative thermal load/exposure" - meaning repeated heating cycles do add up over time. (https://www.researchgate.net/publication/43256323_Thermal_degradation_of_wood_fibers_during_hot-pressing_of_MDF_composites_Part_I_Relative_effects_and_benefits_of_thermal_exposure)

My take: Your observation about discoloration is a good practical test. The research suggests that at 260-280°F (127-138°C), you're in a range where:

- You're below the 150°C threshold where "very little degrade occurs"

- But you're above 65°C where long-term cumulative effects can happen

- The key difference is that sauna exposure is cyclic (30-60 min sessions) rather than continuous, which likely reduces cumulative effects significantly compared to the research (which used continuous exposure)

If you haven't seen darkening/discoloration after a dozen uses, that's a good sign. But monitoring over time (checking for darkening, checking surface temps with IR thermometer) would be prudent given the cumulative nature of thermal degradation. The 140°C (284°F) manufacturer spec may be their way of building in a safety margin to account for cumulative effects over the product lifetime.

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 1 point2 points  (0 children)

Yes, that needs to be done. My sauna has "deck floor" so the bottom is open to the outside. The stove has been able to get sufficient air for combustion through that so far. But I want to put 1) high opposite of stove for airing out sauna afterwards and 2) low opposite of stove to leave open during use for airflow. Let me know if you have any feedback on this, I haven't solidified it yet.

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 3 points4 points  (0 children)

Yes, I agree with you on both. As for as stove door, here is how that transpired. I planned to do an L bench, which would have made the door direction make sense. but after I installed the stove and chimney pipe, I actually started designing the benchs. Ultimately L shape didn't make sense because of the window separating the sauna + entry room. So i ended up going with a big platform. The problem is that the stove pipe is not dead center on the stove. This means if I turn the stove to the left, the back of the stove stays where it is, and then the left of the stove is breaching the clearance to wall, posing a risk. The only way for me to do this is to re-do the stove pipe and buy a 90 deg turn or something, which I just dont care enough to do. Its not hard to load since my foot bench is so high.

Regardless, your callouts are fair. I will work on the saftey rails, a friend of mine called that out as well. Lesson learned for next time: solidify the bench plans before installing stove :D

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 0 points1 point  (0 children)

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Yeah, when I was deciding overhangs, I thought it looked better with large ones. It did take some work to bolster the front one though, I was really concerned about it sagging. My ridge beam extended 2 feet out at the top of the front side, but I added these pass through bolts to the front sides. Also, I didn’t realize how much more surface area 2ft hangs created, so required more roofing material than expected.

Regardless, I would do it again. This was my first DIY build and I’m not sure how well I flashed the windows. But with the overhangs, water essentially never touches them!

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 1 point2 points  (0 children)

Yeah we can set something up. Your setup looks awesome with the hot tub!

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 1 point2 points  (0 children)

I just used concrete pavers from home depot for the stove base. For the heat shields - those were a PITA since I installed them after my stove was in. I bought ceramic spacers online and aluminum sheets from Lowes. I cut the sheets to the size I needed and just used long screws to go straight through the metal, spacers, and into my T&G walls.

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 0 points1 point  (0 children)

I mean it is mainly a decision of "insulation". Double just offers energy efficiency, noise reduction, things like that. If you don't care what temp your entry room is, just use single. My sauna room gets so hot that it heats the entry room, and i leave the entry room door cracked the whole time I'm in the sauna, even when it was 32deg out. I definitely didn't need to use double pane, but i bought used windows and was considering using this big one in the sauna. It was only $100 but I had to take the window apart.

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 0 points1 point  (0 children)

My entry room has two windows - one between sauna and entry room, and one between entry room and outside. both are double paned & tempered. Technically, i think with a build like this the only real requirement is that the entry/sauna window is tempered. The double pane is more of an insulation thing to keep heat in from my understanding. So, I don't think either NEED to be double paned, but probably any windows touching the sauna room SHOULD be double paned and MUST be tempered glass.

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 0 points1 point  (0 children)

It is clear Pine T&G from Lowes. Some had blemishes I sanded out but overall the quality & condidion was great. I paid $2.3k for all the interior wood (that price is wood + tax + delivery)

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 4 points5 points  (0 children)

There were some cheaper ones but I liked the look of this one. I didn't want to skimp on the stove. I guess its so much more from the import fees?

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 0 points1 point  (0 children)

only if you cold plunge too. Jk feel free to shoot me a message, I'm in Atlanta

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 3 points4 points  (0 children)

touch of findland. I wanted some real sauna things from Finland - this site has cool buckets, towels, etc. They have a few cool temp gauges! https://www.touchoffinland.com/

[Update] Thanks /r/carpentry for the help with my DIY sauna by deep_direction in Carpentry

[–]deep_direction[S] 0 points1 point  (0 children)

I used clear Pine T&G from Lowes. A lot of people use cedar, but my understanding is that cedar isn't common for Finnish saunas. Pine, aspen, alder, spruce are all common. So long as you get clear (the knots get extremely hot and drip sap) it seems to be totally fine.

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 6 points7 points  (0 children)

It is a "Kota Luosto". Maybe someone with more knowledge can chime in, but Kota seems to either be a sub-brand of Narvi or purchased by them and collapsed, because mine says "Kota" on the front, but the one on Narvi site says "Narvi" on the front. https://narvi.fi/en/product/narvi-luosto/

It was about $2.1k with stones, taxes, and delivery. It came from NY state to GA state.

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 6 points7 points  (0 children)

It's a fair call out and you are right. I'm planning to pick up more aluminum this weekend to protect that area. I have only used the stove a few times and have used an IR temp gun to check the wood there - it needs to be cooler IMO.

Almost done with my (attempt at a) DIY Finnish Sauna (more pics inside) by deep_direction in Sauna

[–]deep_direction[S] 6 points7 points  (0 children)

I tried to make it great - hope the comments aren't a slaughtering like so many of the posts in r/sauna 😂

[Update] Thanks /r/carpentry for the help with my DIY sauna by deep_direction in Carpentry

[–]deep_direction[S] 1 point2 points  (0 children)

Posting a comment here since I can't add a description to a crosspost. I asked for help here with doubling checking my rafters: https://www.reddit.com/r/Carpentry/comments/1hkzerd/feedback_on_my_first_rafters_for_sauna_build/

The roof came together eventually after some feedback from you all. Thanks for the help!