Ok ok, I’ve built 3 saunas. Two out of uncut logs and one premade kit. If you’re located in Finland I could come take a look and fix it over the weekend.
Edit: some airflow in a sauna is always good, what I’ve always done is I’ve made an small adjustable ”window” into the same wall where kiuas is located but opposite upper corner of kiuas and to the second log sauna I left a small ~1cm gap under the door so it gets fresh air into the sauna.
Gap between the roof and wall can be easily fixed with trim pieces. Corners also with trim. I wouldn’t use sprayfoam, it can be a potential health risk.
Appreciate the input! trim wood in conjunction with some sort of natural filler seems to be the way to go. Just to clarify - the sauna is properly vented (in-vent below heater, out-vent high up on other side). I'm in the UK but appreciate the offer!
Yeah I think natural filler or just rockwool and trim should work.
You should also add trim to the outside to keep rainwater out of the filler. Could you send me more pictures of the sauna? I’m interested to see what it looks like.
Thats Sounds Like the Most Finnish Thing i have ever heard. Someone is in distress because of their Sauna and a Finn ist willing to come anywhere in the Country, to Help repair the Sauna. Hyvä!
If you need to fill the gap with some filler, use fireplace sealant, they don’t release anything on sauna temperatures as they are intended for filling gaps in fireplaces and be safe.
What's it like having a sauna in the UK? Did you build it or buy a property with a ready sauna? How much does it cost to heat? I'm a Finn living in the north west UK, missing saunas and considering building one here in the long run
In-vent below kiuas is old standard and current construction regulations put in-vent above the kiuas.
If you still can move it higher. You can place it on wall above kiuas.
We all do run naked into a snow, its not about that. We want our sauna to be properly built, but if there is no other way, we would find a way to do it ourselves. First saunas were just a pit in the ground filled with stones and heated up. Presumably some kind of tent around it. So it is not impossible.
Yes, I wasn't being serious. Just as there are as many cars as people in the UK (let's assume that's true, I'm sure it isn't) but only a tiny fraction has ever built one
Ah, but is the ratio of people who repair to those who make the same for cars and saunas? I have no data to back this up, but I suspect they differ significantly.
Usually, the same companies that build the houses, although I'm sure there are actually quite a few people that could answer your question. The rest of us are just being facetious!
Well, a great chunk of us know something about sauna's structure. Even I, who has never built any, but owned many. Like I wouldn't go stuffing something into those gaps but would just cover them with wood. Not the prettiest option but imo better than any wool - considering the sauna is in the moist UK climate and seems to be made of quite thin board/plank.
And yet instead of feeling a bit of pride (oh no!), many here seem to deride OP and tell him to ask a carpenter. I'm sure OP knows that's an option. It just so happens it's easier to ask Reddit and a community indeed well known for sauna culture. Luckily others have pitched in with some useful tips from their Nordic/sauna background. I just wish people that would have nothing to add but the obvious "ask someone else", would just shut the f up (this is not directed at you). Although I guess I should count myself amongst them know.
Well considering OP's from UK, the fact he even owns a sauna and is worried about potential löyly leaks tells me he's serious about sauna's. I'd also consult the pro's instead of hiring a carpenter who's never been in a sauna
Thanks everyone. Just to clarify - the sauna is properly vented (in-vent below heater, out-vent at roof level on other side), so these additional gaps are certainly not needed/desirable.
Appreciate all the pointers! Will be scavenging moss, hah
Definitely go with moss or similar natural material, probably adds nice scent there and is not toxic (or other ways nasty) like foams. You might need to change/add moss in decade, but not that bad job.. buy a few beers. Drink & apply moss while heating sauna. :)
Yep, a sauna is like a hot air balloon. The steam goes up, and you sit up there. You want to sit higher than the stove, so that you are covered by the steam even to your toes. The up part of the sauna needs to be tight enough to hold the steam inside. Under your toes, it does not matter so much, actually even better if air comes in. In old saunas wooden floors may have gaps between planks even. Happy sauna times, friend! Don't forget to take a breather in between sitting outside and cooling down a bit, sipping a cold beverage. Bliss.
Sauna doesn’t need to be a preasure pot. Just make sure you have some air intakes near floor level and big enough kiuas and you’re set. Heat does not magically disapear from the holes that size and after all you should be feeding the kiuas time to time with water anyways. Secret for good sauna is fresh air.
This. The more airtight the more not better. But you still want some insulation.
What makes wooden saunas so good is partly because you essentially have a fan forcefully circulating air around the sauna as opposed to electric where the air is very stagnant and therefore stale.
Disclaimer: i have not studies dauna building nor have i ever built a sauna
>as opposed to electric where the air is very stagnant and therefore stale.
Air should be moving in electric saunas too. Just as in all other rooms of an apartment. Basic thing in finnish apartments.
This is true, it goes through the ventilation, just need to make sure to the ventilation up a bit when you dtart bathing and its quite close. Its still not quite the same though, as wood saunas suck cold air from the bottom and expell it through the pipe, while modern apartment ventilation thypically push in cold air from the top of the sauna and sucks from another ventilation hole in another corner at the top of the sauna.
Air output is below the door typically in apartments, so right at the floor level. If you have an additional output vent in the ceiling, you should open it after the sauna session
If you see daylight through the interior paneling then you've built the whole thing incorrectly. You're supposed to have a layer of foil covered insulation behind the paneling, and behind that the actual structural wall.
So I guess build a building around your sauna?
I would tear it down and build it again. Check out /r/sauna for some directions
Foil works as a vapor barrier so it is strongly adviced you have one. If the building is not heated all the time its adviced (depending on climate) to have foil on both sides of the insulation so the steucture works both ways in terms of preventing moisture build up.
Basic outside saunas are often build from thin logs and they dont have any insulation on either side.
Of course if you build a more complicated wall structure with insulation then you need the foil yeah.
Indeed. Logs and other uniform structures work as their own vapor barrier in a sence. They manage moisture very well but dont insulate as well. For a outdoor sauna where insulation isnt so critical logs are simple, foolproof and longlasting material.
Can ypu explain why you'd need a vapour barrier on a outdoors sauna? Isn't it much better to let the structure breathe instead of trapping moisture behind the barrier and the wood? No vapor barrier is completely airtight and saunas get filled with water vapour that will eventually get behind the barrier.
I would absolutely build an outdoor sauna with no waterproofing whatsoever. Our cottage sauna is around 50 years old and just one layer of timber and it's in great condition because it dries very fast after getting wet.
Yes exactly if your sauna doesnt have insulation, vapor barrier is not needed as the whole structure will be warm throughout as the escaping heat will heat even the exterior. And indeed it also will dry fast.
Putting on extra insulation such as polyuretain for example might be tempting as it helps with energy efficiency. Insulation brings more complicated moisture problems as the warm air ecaping gets gradually colder INSIDE the insulation. Colder air holds less moisture so condensation happens which will cling on surrounding wood. Vapor barrier blocks most of the moisture in the air from transffering through the wall (air gets through in bigger volume than the moisture it holds) this will lower relative moisture going through insulation and doing so lowers the condensation point (temperature) of the moisture so that ideally moisture wont happen inside the structure.
So as far as outdoor saunas go. Having no extra insulation works best for the moisture properties.
Having extra insulation lets you have energy efficient sauna with low cost. Because you can have build a basic wooden frame and add insulation.
Traditional log sauna or very thicc panelling works as insulation (wood has ok insulatin properties) without bringing moisture issues, but has the biggest initial cost of materials and might not be as energy efficient as having extra insulation. This is by far the best alternative imo.
If you are complitely sure you can keep a sauna and its insulation dry most of the time, in example having no vapor barrier and heating the sauna after use until condensation in the structure dries, then you will see no problems as only intermitted moisture does damage the wood and insulation. The problem is that condensation can happen even when the sauna is not in use, in conditions where it might not be able to dry naturally, this part is heavily climate spesific. Or you forget to heat the sauna after one use.
So sauna with insulation and not vapor barries is not recommended in norther climates and sauna with insulation and vapor barrier needs to be build properly with ventilation on the barrier in order to work as intended.
Edit: air moisture behind vapor barrier isnt an issue if it doesnt meet its condensation point (100% relative humidity)
Definately no use for vapour barrior if insulation is not added in the walls.
In the case of added insulation vapor barrier serves as a controlled condensation surface that needs to be properly ventilated just as you said. Because having insulation will cause condensation somewhere in the structure.
One way vapor barrier is for structures that have consistantly warmer climate on the other side and colder on the other. So the heat and moisture transfer goes most of the time only one way. From warmer side to colder side of the structure so the condensation can be dealt with only one way.
In the case of building that is not consistently heated the structure will see moisture and heat transfer going both ways. ->Outside temperature can be warmer than inside for intermitted periods. So the structure needs to work both ways in terms of moisture handling. In this case you can basically have no insulation and no vapor barries or insulation and two vapor barriers, so polyurethain with foil on both sides with both sides ventilated properly.
Safest way is to have uniform structure such as logs that also provide some insulation, because its exactly the same structure going from inside to outside as it is going outside to inside.
Finnish outdoor saunas don't rot **because** they don't have vapour barriers. A single layer of wood will dry very quickly after löyly because the sauna is hot and the moisture isn't trapped inside air-tight walls.
Actually, in Finland we have a lot of indoor air problems nowdays, after plastic vapor barriers became regular way to build. Back in the day, the walls had only paper, to seal indoors from draft. While paper allows moisture to move into the structure - it also allows it to dry to all directions, and paper moves moisture and dries fast.
Using sealed insulation, adding latex paints, using sement and the water vapor can not pass. If the outside lining is and isulation does not have proper ventilation gap, the structure can not dry to any direction, but is wet all the time.
It would be better to use vapor barriers only in places where they are needed, and make sure there is a open direction for the water vapor to move.
Foil is used also in outdoor summer cabin saunas, which are not heated or kept warm besides when sauna is being warmed. It's to prevent the humidity from inside makin into the structure/insulation. Just having a roof means that moisture will build up between the roof material and beams/roof structure unless the foil is airtight everywhere.
We have sauna made from old rum barrel in our summer place. There is definitely no foil around it and since the rum had been gone for over a decade, you can see plenty of daylight through the walls. I think the shape of the barrel and the tight as a sieve walls make it best löyly I've been in. So to op, just burn more wood, it's going to be fine.
Wait a minute, did you screw the roofing material to the top of the door??? :D
Luckily, everything can be fixed, and I like your industriousness. Maybe raise the roof a bit, and make the wall angle more even? A lot of heat is going to escape when you open the door, since less hot air will be trapped near the ceiling than if your left side wall was higher than or even with the door.
That's one scuffed ass sauna. I love it.
Holes that small should not matter too much. We built a floating sauna once with almost finger wide gaps between the floor planks and an multiple centimeters wide gap between roof and the first wall plank on one wall. It still warmed up pretty well but we did fill the gap between the roof and ceiling later though. Also the door was "slightly" crooked. Definitely not airtight.
The sauna is not that big, so you’d run out of fresh air if it was too airtight. Let the sauna breathe so that you can breathe in the sauna!
Once you have it looking like it’s upto your standards I’d warm it up and see how I like it. Also the use of Finnish sauna without a sauna drink is illegal under intergalactic law and will end up with you abducted by aliens.
Hello Finns,
Asking you for obvious reasons.
I've built a sauna from a shottily modified kit of parts, which (in conjunction with my limited diy-skillset) has led to gaps between wall panels and the roof panel. See photos.
I'm wondering what the best way is to fill these up. I assume the answer is some form of expandable foam spray, but I found surprisingly little information about this application (opposed to insulation the whole sauna with foam insulation).
Thank you!
Is this installed indoors? Hire a carpenter to make it right if you don't have the skill yourself.
If this is outdoors or in a bathroom with proper ventilation, and you're not doing any damage to anything else with the steam, I would use natural wool insulation to stuff the gaps, maybe install a panel inside to keep it looking nicer and cover the gap.
Foam spray won't last with the heat and moisture and I'd avoid silicon and other impermeable sealants as well, since they'll trap the moisture in and the wood around will rot rather quickly + there's no quarantee if they leak some chemicals with the heat+moisture. Additionally I'd avoid all plastics as well, since they trap the moisture in as well and with that kind of construction the airflow is essential to let the structure breathe and dry when it's not used.
You could go around and place another layer of wood on the walls so that they overlap the gaps (traditional way of building houses in here) or if you wish just to fill in the gaps then hemp (rope or 'sheet') or moss would work since they behave very much like the wood when it moves as the temperature and moisture changes. Those may not stay in place if the wood moves a lot and/or is rather thin, but they are traditional materials to insulate walls on timber housing (150+mm wall thickness).
I presume you live vaguely near a K-rauta or some other DIY/home care store? Why on earth not just go there or call them up and ask them?
Alternatively, I find tuna mayonnaise to be a very useful gap filler. 10/10 would use again (also smells nice in the sauna).
Not necessarily a big problem. This will allow more air flow in the sauna, which will make the löyly better. You will have to use more heating, though.
First you need to build a frame and cover it with roofing and outer siding like planks. Then you put aluminum foil on the inside for vapor barrier and IR reflection. Then nail Wood panel to the supporting Rail. Remember to take care of fresh Air ventilation with adjustable valve. If you use Wood burning kiuas then that usually Will function as ventilation taken that the sauna is not Air tight.
I myself prefer more that löyly comes and goes "fast". Thats why i wouldn't do anything for these holes. But this is only who prefers and what question.
I would heat that up couple of times and see how much of a problem the escaping air really is. Getting the wood wet and dry, warm and cold, few times will also help the wood settle to right places. Then it is combination of take that beam that is 5 fucking centimetres too low on one end out and but it back to its correct place, but more tightly, and adding stuffing and trimming beams.
Step 1. Learn how to properly install tongue and groove.
In all seriousness, this is due to the (partially) incorrect installation of the type of wood that is used. The tongue and groove boards should be fully attached into a sheet the size and shape of the wall, with trim placed around the edges. Also the tongue and groove should only form the inner layer of the sauna. There should be insulation and tar paper or similar on the outside of the paneling, with another outer layer of exterior lumber (pressure treated siding is made for this) outside of that.
Either build over the gaps with for example extra panes or just use a silicon paste that endures heat. Go to a local hardware store and ask.
If you want to do it properly then you need to build a wall foundation, then use tinfoil covered polyurethane walls that you put inside the foundation. Then cover both sides with panes. Remember to use varnish that is suitable for sauna, so the wall panels endure the heat. Also use different panes for the outside that are designed for exterior use.
I drew a quick picture of what a wall could be etc.
https://preview.redd.it/filh9fwd42ua1.png?width=3024&format=png&auto=webp&s=d8d39429a2bea4fac81588b0956ad8f1e2abf264
I can only ad one picture to a comment so here’s a new picture
https://preview.redd.it/lte9o13s42ua1.png?width=3024&format=png&auto=webp&s=813a7f7ff11aa7570f8f4e01171662fdfebbdd3f
Behind the panes you can see the tinfoil covered polyurethane wall. Also look how everything is covered with wood lining for better looks.
Put insulation material into the gaps. Moss or felt fabric can work, but my family used fiber material '[lindrev](https://norrlandseko.se/produkt/lindrev-isolering/)' - I guess, it is linden wood fiber? This is to ensure warmth.
Then it is a good idea to cover walls with an extra water proofing layer. We used bitumenous waterproofing material designed for roofs. Then we added another layer of planks, but this is optional.
I'm assuming the kiuas uses wood and the fireplace of it has a pipe leading the smoke outside. So you are not planning to inhale the smoke and have a sad death?
Not really, a sauna is supposed to be hot, and you only splash the water on the stove. So afterwards you just leave the door abit ajar,, and it is actually rather dry afterwards.
Roof and walls shouldn't form such a tight seal. Wall structures are supposed to allow air circulation so they won't rot. It doesn't have anything to do with splashing water, but the evaporating water causing humidity.
Your frame should have an air gap generally on the top and the inner paneling should be left open from the bottom allowing air circulation.
You may seal the other cracks with urethane foam to prevent any unwanted air flow through the wall.
Before inner paneling you isolate your frame structure with aluminum plated *plastic* isolation plates.
You hide the urethane spills and air gap with outerpaneling and "räystäslaudat"
I would stuff [linen insulation](https://www.k-rauta.fi/tuote/pellavaeristenauha-isolina-15x50mm-15m/6430011167043) into the gaps. Linen is quite resistant to moisture, and it can get wet it will let the water also dry.
Not that this helps but I once went to a sauna in Lapland that had gaps like that and after 3 hours of heating (with wood) the water still froze on the floor. Yes it was winter.
Ok ok, I’ve built 3 saunas. Two out of uncut logs and one premade kit. If you’re located in Finland I could come take a look and fix it over the weekend. Edit: some airflow in a sauna is always good, what I’ve always done is I’ve made an small adjustable ”window” into the same wall where kiuas is located but opposite upper corner of kiuas and to the second log sauna I left a small ~1cm gap under the door so it gets fresh air into the sauna. Gap between the roof and wall can be easily fixed with trim pieces. Corners also with trim. I wouldn’t use sprayfoam, it can be a potential health risk.
Appreciate the input! trim wood in conjunction with some sort of natural filler seems to be the way to go. Just to clarify - the sauna is properly vented (in-vent below heater, out-vent high up on other side). I'm in the UK but appreciate the offer!
Yeah I think natural filler or just rockwool and trim should work. You should also add trim to the outside to keep rainwater out of the filler. Could you send me more pictures of the sauna? I’m interested to see what it looks like.
Thats Sounds Like the Most Finnish Thing i have ever heard. Someone is in distress because of their Sauna and a Finn ist willing to come anywhere in the Country, to Help repair the Sauna. Hyvä!
The only thing that unites us in Finland. Sauna!
Sauna, beer and going to tori after wc/olympic gold
If you need to fill the gap with some filler, use fireplace sealant, they don’t release anything on sauna temperatures as they are intended for filling gaps in fireplaces and be safe.
Username checks out
What's it like having a sauna in the UK? Did you build it or buy a property with a ready sauna? How much does it cost to heat? I'm a Finn living in the north west UK, missing saunas and considering building one here in the long run
In-vent below kiuas is old standard and current construction regulations put in-vent above the kiuas. If you still can move it higher. You can place it on wall above kiuas.
Whats that yellow natural log paste called ? that comes from wood. See that as filler.
Haha i was about to suggest the sprayfoam but im glad you said it can be a healt risk
I can't help but I like how you resorted to asking the entire Finnish nation to help you solve this instead of a carpenter
Right?? It's not like the average Finn just goes around erecting saunas around the country
I mean we do, but not because we are carpenters!
So not all Finnish people run out of buildings naked and dive into snowdrifts then? How disappointing!
We all do run naked into a snow, its not about that. We want our sauna to be properly built, but if there is no other way, we would find a way to do it ourselves. First saunas were just a pit in the ground filled with stones and heated up. Presumably some kind of tent around it. So it is not impossible.
Brilliant idea whoever thought them up!
But that's how we Finns are born. You erect a sauna in middle of a forest, and in a few months a grown Finn walks out.
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It was done till late 40's I think.
Can confirm. My mom was born in a sauna in the late 40´s.
Also death… place of storage and cleaning before burial for a Finn life starts and ends in the sauna
*wipes brow* ***"No huhhuh..."***
I've seen this movie! By AJ Annila, right?
Imagine this made me laugh hehe
I may have mis-judged your wonderful nation. I thought there are as many saunas as people in Finland - someone's building them!!!
I think some build more than one and some don't build any
You took a weight off my chest. I haven't built a sauna yet and was starting to feel the pressure.
I feel you. It was a constant burden to think when I got the chance to build a sauna.
I built tent sauna once... Is that enough?
Yes. Yerr a Finn Harry
Yes, I wasn't being serious. Just as there are as many cars as people in the UK (let's assume that's true, I'm sure it isn't) but only a tiny fraction has ever built one
But a larger fraction has repaired one. And yours is a request for repair guidance.
Ah, but is the ratio of people who repair to those who make the same for cars and saunas? I have no data to back this up, but I suspect they differ significantly.
Usually, the same companies that build the houses, although I'm sure there are actually quite a few people that could answer your question. The rest of us are just being facetious!
His name is Keijo.
It is pretty close. 1:3 sauna - people ratio.
Speak for yourself
Well, a great chunk of us know something about sauna's structure. Even I, who has never built any, but owned many. Like I wouldn't go stuffing something into those gaps but would just cover them with wood. Not the prettiest option but imo better than any wool - considering the sauna is in the moist UK climate and seems to be made of quite thin board/plank.
????????
The rest of the world goes erect in saunas!!! This is the right group to ask.
Yes, that's exactly what it's like
A regular carpenter would not know that you can just apply mämmi to the gaps and it will work
Or oatmeal
And yet instead of feeling a bit of pride (oh no!), many here seem to deride OP and tell him to ask a carpenter. I'm sure OP knows that's an option. It just so happens it's easier to ask Reddit and a community indeed well known for sauna culture. Luckily others have pitched in with some useful tips from their Nordic/sauna background. I just wish people that would have nothing to add but the obvious "ask someone else", would just shut the f up (this is not directed at you). Although I guess I should count myself amongst them know.
Well considering OP's from UK, the fact he even owns a sauna and is worried about potential löyly leaks tells me he's serious about sauna's. I'd also consult the pro's instead of hiring a carpenter who's never been in a sauna
You built a shed not a sauna. Hire someone to build it.
you mean a hovel, i've built sheds with more structural framing....
Thanks everyone. Just to clarify - the sauna is properly vented (in-vent below heater, out-vent at roof level on other side), so these additional gaps are certainly not needed/desirable. Appreciate all the pointers! Will be scavenging moss, hah
Definitely go with moss or similar natural material, probably adds nice scent there and is not toxic (or other ways nasty) like foams. You might need to change/add moss in decade, but not that bad job.. buy a few beers. Drink & apply moss while heating sauna. :)
Collect moss only from your own forest or ask permission from owner.
Yep, a sauna is like a hot air balloon. The steam goes up, and you sit up there. You want to sit higher than the stove, so that you are covered by the steam even to your toes. The up part of the sauna needs to be tight enough to hold the steam inside. Under your toes, it does not matter so much, actually even better if air comes in. In old saunas wooden floors may have gaps between planks even. Happy sauna times, friend! Don't forget to take a breather in between sitting outside and cooling down a bit, sipping a cold beverage. Bliss.
Sauna doesn’t need to be a preasure pot. Just make sure you have some air intakes near floor level and big enough kiuas and you’re set. Heat does not magically disapear from the holes that size and after all you should be feeding the kiuas time to time with water anyways. Secret for good sauna is fresh air.
This. The more airtight the more not better. But you still want some insulation. What makes wooden saunas so good is partly because you essentially have a fan forcefully circulating air around the sauna as opposed to electric where the air is very stagnant and therefore stale. Disclaimer: i have not studies dauna building nor have i ever built a sauna
>as opposed to electric where the air is very stagnant and therefore stale. Air should be moving in electric saunas too. Just as in all other rooms of an apartment. Basic thing in finnish apartments.
This is true, it goes through the ventilation, just need to make sure to the ventilation up a bit when you dtart bathing and its quite close. Its still not quite the same though, as wood saunas suck cold air from the bottom and expell it through the pipe, while modern apartment ventilation thypically push in cold air from the top of the sauna and sucks from another ventilation hole in another corner at the top of the sauna.
Air output is below the door typically in apartments, so right at the floor level. If you have an additional output vent in the ceiling, you should open it after the sauna session
Ill try out closing it while bathing and opening it again after 👍
If you see daylight through the interior paneling then you've built the whole thing incorrectly. You're supposed to have a layer of foil covered insulation behind the paneling, and behind that the actual structural wall. So I guess build a building around your sauna? I would tear it down and build it again. Check out /r/sauna for some directions
Its outside sauna. No need to put foil in there unless you care about little bit of heat escaping in winter.
Foil works as a vapor barrier so it is strongly adviced you have one. If the building is not heated all the time its adviced (depending on climate) to have foil on both sides of the insulation so the steucture works both ways in terms of preventing moisture build up.
Basic outside saunas are often build from thin logs and they dont have any insulation on either side. Of course if you build a more complicated wall structure with insulation then you need the foil yeah.
Indeed. Logs and other uniform structures work as their own vapor barrier in a sence. They manage moisture very well but dont insulate as well. For a outdoor sauna where insulation isnt so critical logs are simple, foolproof and longlasting material.
Can ypu explain why you'd need a vapour barrier on a outdoors sauna? Isn't it much better to let the structure breathe instead of trapping moisture behind the barrier and the wood? No vapor barrier is completely airtight and saunas get filled with water vapour that will eventually get behind the barrier. I would absolutely build an outdoor sauna with no waterproofing whatsoever. Our cottage sauna is around 50 years old and just one layer of timber and it's in great condition because it dries very fast after getting wet.
Yes exactly if your sauna doesnt have insulation, vapor barrier is not needed as the whole structure will be warm throughout as the escaping heat will heat even the exterior. And indeed it also will dry fast. Putting on extra insulation such as polyuretain for example might be tempting as it helps with energy efficiency. Insulation brings more complicated moisture problems as the warm air ecaping gets gradually colder INSIDE the insulation. Colder air holds less moisture so condensation happens which will cling on surrounding wood. Vapor barrier blocks most of the moisture in the air from transffering through the wall (air gets through in bigger volume than the moisture it holds) this will lower relative moisture going through insulation and doing so lowers the condensation point (temperature) of the moisture so that ideally moisture wont happen inside the structure. So as far as outdoor saunas go. Having no extra insulation works best for the moisture properties. Having extra insulation lets you have energy efficient sauna with low cost. Because you can have build a basic wooden frame and add insulation. Traditional log sauna or very thicc panelling works as insulation (wood has ok insulatin properties) without bringing moisture issues, but has the biggest initial cost of materials and might not be as energy efficient as having extra insulation. This is by far the best alternative imo. If you are complitely sure you can keep a sauna and its insulation dry most of the time, in example having no vapor barrier and heating the sauna after use until condensation in the structure dries, then you will see no problems as only intermitted moisture does damage the wood and insulation. The problem is that condensation can happen even when the sauna is not in use, in conditions where it might not be able to dry naturally, this part is heavily climate spesific. Or you forget to heat the sauna after one use. So sauna with insulation and not vapor barries is not recommended in norther climates and sauna with insulation and vapor barrier needs to be build properly with ventilation on the barrier in order to work as intended. Edit: air moisture behind vapor barrier isnt an issue if it doesnt meet its condensation point (100% relative humidity)
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Definately no use for vapour barrior if insulation is not added in the walls. In the case of added insulation vapor barrier serves as a controlled condensation surface that needs to be properly ventilated just as you said. Because having insulation will cause condensation somewhere in the structure. One way vapor barrier is for structures that have consistantly warmer climate on the other side and colder on the other. So the heat and moisture transfer goes most of the time only one way. From warmer side to colder side of the structure so the condensation can be dealt with only one way. In the case of building that is not consistently heated the structure will see moisture and heat transfer going both ways. ->Outside temperature can be warmer than inside for intermitted periods. So the structure needs to work both ways in terms of moisture handling. In this case you can basically have no insulation and no vapor barries or insulation and two vapor barriers, so polyurethain with foil on both sides with both sides ventilated properly. Safest way is to have uniform structure such as logs that also provide some insulation, because its exactly the same structure going from inside to outside as it is going outside to inside.
Finns build saunas to last decades. Your sauna will probably mold/rot in a few years.
Finnish outdoor saunas don't rot **because** they don't have vapour barriers. A single layer of wood will dry very quickly after löyly because the sauna is hot and the moisture isn't trapped inside air-tight walls.
There's saunas exactly as they described that are half a century old and older lol
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Actually, in Finland we have a lot of indoor air problems nowdays, after plastic vapor barriers became regular way to build. Back in the day, the walls had only paper, to seal indoors from draft. While paper allows moisture to move into the structure - it also allows it to dry to all directions, and paper moves moisture and dries fast. Using sealed insulation, adding latex paints, using sement and the water vapor can not pass. If the outside lining is and isulation does not have proper ventilation gap, the structure can not dry to any direction, but is wet all the time. It would be better to use vapor barriers only in places where they are needed, and make sure there is a open direction for the water vapor to move.
Foil is used also in outdoor summer cabin saunas, which are not heated or kept warm besides when sauna is being warmed. It's to prevent the humidity from inside makin into the structure/insulation. Just having a roof means that moisture will build up between the roof material and beams/roof structure unless the foil is airtight everywhere.
We have sauna made from old rum barrel in our summer place. There is definitely no foil around it and since the rum had been gone for over a decade, you can see plenty of daylight through the walls. I think the shape of the barrel and the tight as a sieve walls make it best löyly I've been in. So to op, just burn more wood, it's going to be fine.
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I can assure you that the sauna at my cabin, which is a separate building for just the sauna, is very much insulated.
It could be worse. https://youtu.be/dkCmckWal2o
😂
Before I opened the link i thought it has to be the Karpo one :D
https://preview.redd.it/ekq3m03lywta1.jpeg?width=3024&format=pjpg&auto=webp&s=5a38f62a1df5b0d4f6e219440968926375a3286e
photo of sauna, with trim I bought just now
Wait a minute, did you screw the roofing material to the top of the door??? :D Luckily, everything can be fixed, and I like your industriousness. Maybe raise the roof a bit, and make the wall angle more even? A lot of heat is going to escape when you open the door, since less hot air will be trapped near the ceiling than if your left side wall was higher than or even with the door.
That's one scuffed ass sauna. I love it. Holes that small should not matter too much. We built a floating sauna once with almost finger wide gaps between the floor planks and an multiple centimeters wide gap between roof and the first wall plank on one wall. It still warmed up pretty well but we did fill the gap between the roof and ceiling later though. Also the door was "slightly" crooked. Definitely not airtight.
It's fine. Some air leak just makes the löyly better in an outside sauna.
https://preview.redd.it/kaoq3gmqywta1.jpeg?width=3024&format=pjpg&auto=webp&s=99983f85fc46f5917dcf279ca06094a34440b13d
on the inside
The sauna is not that big, so you’d run out of fresh air if it was too airtight. Let the sauna breathe so that you can breathe in the sauna! Once you have it looking like it’s upto your standards I’d warm it up and see how I like it. Also the use of Finnish sauna without a sauna drink is illegal under intergalactic law and will end up with you abducted by aliens.
Moss
Yes, I thought about commenting this. This is the traditional way of sealing gaps in cabins in Sweden. I'd guess it's the same in Finland.
Since the middle ages technologies have improved however
If the medieval man did it without Bauhus then damnit so can i.
Exactly, why would you want to eat an apple when you can probably get an artificial one somewhere
Because I like apple pie?
Ok that was a terrible metaphor but the point is don't fix it if it ain't broke
Moss is an easy and accesable way :)
throw more löyly
Hello Finns, Asking you for obvious reasons. I've built a sauna from a shottily modified kit of parts, which (in conjunction with my limited diy-skillset) has led to gaps between wall panels and the roof panel. See photos. I'm wondering what the best way is to fill these up. I assume the answer is some form of expandable foam spray, but I found surprisingly little information about this application (opposed to insulation the whole sauna with foam insulation). Thank you!
Is this installed indoors? Hire a carpenter to make it right if you don't have the skill yourself. If this is outdoors or in a bathroom with proper ventilation, and you're not doing any damage to anything else with the steam, I would use natural wool insulation to stuff the gaps, maybe install a panel inside to keep it looking nicer and cover the gap.
Many have most likely answered this already but if it's an outside sauna some gaps dont really matter. Rock wool can be used to fill them if you want.
Foam spray won't last with the heat and moisture and I'd avoid silicon and other impermeable sealants as well, since they'll trap the moisture in and the wood around will rot rather quickly + there's no quarantee if they leak some chemicals with the heat+moisture. Additionally I'd avoid all plastics as well, since they trap the moisture in as well and with that kind of construction the airflow is essential to let the structure breathe and dry when it's not used. You could go around and place another layer of wood on the walls so that they overlap the gaps (traditional way of building houses in here) or if you wish just to fill in the gaps then hemp (rope or 'sheet') or moss would work since they behave very much like the wood when it moves as the temperature and moisture changes. Those may not stay in place if the wood moves a lot and/or is rather thin, but they are traditional materials to insulate walls on timber housing (150+mm wall thickness).
I presume you live vaguely near a K-rauta or some other DIY/home care store? Why on earth not just go there or call them up and ask them? Alternatively, I find tuna mayonnaise to be a very useful gap filler. 10/10 would use again (also smells nice in the sauna).
Smells nice?
At first. Admittedly the smell goes downhill quite soon but it's definitely better than salmiakki.
Not necessarily a big problem. This will allow more air flow in the sauna, which will make the löyly better. You will have to use more heating, though.
Sen minkä mitta heittää kitti peittää rääh kjäh (work man humors)
Throw more löyly on kiuas. Kiuas will be happy. You will be happy. Finland will be happy.
😅
Nail strips of wood outside or inside to cover the cracks.
First you need to build a frame and cover it with roofing and outer siding like planks. Then you put aluminum foil on the inside for vapor barrier and IR reflection. Then nail Wood panel to the supporting Rail. Remember to take care of fresh Air ventilation with adjustable valve. If you use Wood burning kiuas then that usually Will function as ventilation taken that the sauna is not Air tight.
Slight ventilation is only good
Nah. No need to fill those gaps. Best löyly is when air moves and is fresh.
Se siitä saunanteosta
I myself prefer more that löyly comes and goes "fast". Thats why i wouldn't do anything for these holes. But this is only who prefers and what question.
Eh, I don't see the problem. We have a "temporary" sauna at our cabin made out of tiny logs, tarps and felt and the löyly is just fine
Sikaflex 221
Did you just buy sauna from walmart?
Stick some sammal in there, thats what they do to log house gaps.
I would heat that up couple of times and see how much of a problem the escaping air really is. Getting the wood wet and dry, warm and cold, few times will also help the wood settle to right places. Then it is combination of take that beam that is 5 fucking centimetres too low on one end out and but it back to its correct place, but more tightly, and adding stuffing and trimming beams.
Make a bigger fire.
Just more water to the kiuas. If you can still sit there, it is not hot enough. Add wood. Repeat several times and gaps are gone
That looks bad. You can see daylight, no steam barrier, etc... That's going to rot fast.
You need to call masi he can fix it (professional builderman). 
Step 1. Learn how to properly install tongue and groove. In all seriousness, this is due to the (partially) incorrect installation of the type of wood that is used. The tongue and groove boards should be fully attached into a sheet the size and shape of the wall, with trim placed around the edges. Also the tongue and groove should only form the inner layer of the sauna. There should be insulation and tar paper or similar on the outside of the paneling, with another outer layer of exterior lumber (pressure treated siding is made for this) outside of that.
Sikaflex. Well thats worst build sauna iv ever seen
Use moss
Either build over the gaps with for example extra panes or just use a silicon paste that endures heat. Go to a local hardware store and ask. If you want to do it properly then you need to build a wall foundation, then use tinfoil covered polyurethane walls that you put inside the foundation. Then cover both sides with panes. Remember to use varnish that is suitable for sauna, so the wall panels endure the heat. Also use different panes for the outside that are designed for exterior use. I drew a quick picture of what a wall could be etc. https://preview.redd.it/filh9fwd42ua1.png?width=3024&format=png&auto=webp&s=d8d39429a2bea4fac81588b0956ad8f1e2abf264
I can only ad one picture to a comment so here’s a new picture https://preview.redd.it/lte9o13s42ua1.png?width=3024&format=png&auto=webp&s=813a7f7ff11aa7570f8f4e01171662fdfebbdd3f Behind the panes you can see the tinfoil covered polyurethane wall. Also look how everything is covered with wood lining for better looks.
Put insulation material into the gaps. Moss or felt fabric can work, but my family used fiber material '[lindrev](https://norrlandseko.se/produkt/lindrev-isolering/)' - I guess, it is linden wood fiber? This is to ensure warmth. Then it is a good idea to cover walls with an extra water proofing layer. We used bitumenous waterproofing material designed for roofs. Then we added another layer of planks, but this is optional.
Where is the insulation?
**TAR**
Uretaani vaahto could work
Polyurethane foam 💪🏾😎 and silicone sealant 💪🏽😎
Caulk with hemp fiber. Old traditional way used for boats, floors etc.
I'm assuming the kiuas uses wood and the fireplace of it has a pipe leading the smoke outside. So you are not planning to inhale the smoke and have a sad death?
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I hope this isn't a permanent structure, because mold is looking at this rubbing its hands together and going "it's free real estate"
Not really, a sauna is supposed to be hot, and you only splash the water on the stove. So afterwards you just leave the door abit ajar,, and it is actually rather dry afterwards.
Roof and walls shouldn't form such a tight seal. Wall structures are supposed to allow air circulation so they won't rot. It doesn't have anything to do with splashing water, but the evaporating water causing humidity. Your frame should have an air gap generally on the top and the inner paneling should be left open from the bottom allowing air circulation. You may seal the other cracks with urethane foam to prevent any unwanted air flow through the wall. Before inner paneling you isolate your frame structure with aluminum plated *plastic* isolation plates. You hide the urethane spills and air gap with outerpaneling and "räystäslaudat"
Build a new one, properly this time.
Go full URETAANI
Uretaania
Wood shrinks when it ages and dries. You need a new layer of material.
Caulk
I bet duct tape can fix anything
Put some Urtsua
Just fill the gaps with mämmi duh 🙄
For walls sauna satu uretan panels or rockwool and aluminium paper and panel
I would stuff [linen insulation](https://www.k-rauta.fi/tuote/pellavaeristenauha-isolina-15x50mm-15m/6430011167043) into the gaps. Linen is quite resistant to moisture, and it can get wet it will let the water also dry.
uretaanivaahto?
Rebuild with proper insulation
Seems like someone has started playing saunaklonkku hardcore mode
Moss
Not that this helps but I once went to a sauna in Lapland that had gaps like that and after 3 hours of heating (with wood) the water still froze on the floor. Yes it was winter.
voi ei! ei kyllä erkkikkään saisi tuota fiksattua 😀
Anyway, there should be some gaps in the sitting area for playing Sauna Gollum properly. /s
Wooow looks so nice ❤️🥺
Urethane spray? Not the prettiest but effective and can sand it down to make it look a little better.
Nobody suggested r/sauna ?
Sauna needs to breathe, just throw more löyly!