Kit Sauna Reviews

The following reviews are based on the functional design of these saunas and how they compare to Finnish sauna design principles. For a better understanding of sauna and what is critical for a good sauna see ‘Intro to Sauna’ and ‘Notes on Building a Sauna’ in the menu above as well as Lassi Liikkanen’s ‘‘Secrets of Finnish Sauna Design’ book.

One important note. While all of the kits currently available in the U.S. appear to be quite poor for sauna, many are better than a smaller barrel. So an Almost Heaven Allegheny or Finnleo Northstar will provide a better sauna experience than any Barrel under about 9’. But both of those, along with every kit I’m aware of currently available in the U.S., will be a worse sauna experience than one built with proper bench heights and other elements.

 

Common Mistakes

There are three critical elements that it seems every kit manufacturer in the english speaking world doesn’t understand about sauna:

“Feet above the stones” is The First Law Of löyly. And for good reason. Heat rises, the convective loop is above the top of the stones which results in less stratification and makes this critical to a good sauna experience (and to good hygiene). Finns (and Swedes, Germans, etc.) do not want a sauna with a foot bench that’s too low – below the top of the stones or below the bottom third of the space unless space constraints allow no alternative. 

Proper ventilation is critical as otherwise bathers begin to feel the effects of suffocation from too much CO2 (such as feeling lightheaded, dizzy, etc.). Proper ventilation is also needed for removal of moisture, odors, VOC’s and pathogens.   For electrically heated saunas this must include a fresh air supply vent above the stove and a mechanical powered exhaust below the foot bench. Natural convection, as these kits have, is for heater over temp sensor cooling and does not provide ventilation for bathers.

Interior Volume is critical. A sauna should have a minimum of 70 cubic feet of interior volume per person plus an additional 35 cubic feet. This is for people to breath. Sauna builders in Scandinavia often aim for twice that amount of interior volume per bather. Less volume results in people rebreathing too much of their own and others exhaled breath and so high CO2 and pathogen levels.

Deceptive Advertising. There is perhaps no better proof of how gullible and ignorant Americans are than the snake oil of the U.S. sauna industry. For more see Quackery and Sauna Frauds in the top menu.

Note: If you find a kit that is built correctly then please let us know.

 

When A 7’ Kit Might Be OK

If you are very limited in space then a good kit sauna might be an OK option. In a smaller floor space such as 3’x4’ a custom built sauna may not be able to have benches up much higher than the kits sold as saunas in the U.S. and you’ll be very close to the heater either way. So here you can purchase a kit, add proper ventilation, and have about as good a sauna as possible for the space.

In a 4’x4’ space you can have benches up a bit higher and so a custom/DIY build will provide a noticeably better sauna experience though not as much better as in a larger sauna. On the other hand some people may not like the tightness of the steps that this requires. A 4’x4’ kit such as a Finnleo Northstar isn’t a bad option in this case.

For a floor space larger than 4’x4′ a custom or DIY with proper ceiling/bench heights, ventilation and other elements discussed in Trumpkin’s Notes on Building a Sauna will provide a much better sauna experience.

If your only option is a interior location with a 7’ height limit then a interior kit of any size may be a good option. Similar to above, a custom/DIY will not be able to improve on the bench height problem. In this scenario I’d recommend a Finnleo as they have better bench designs. You should also plan to fix the ventilation and maybe remove the back slat of benches.

If A Low Ceiling Can’t Be Avoided, Maybe Get A Huum – An open mesh style heater results in a less defined löyly cavity due to a less defined convective loop. With a proper higher ceiling and benches this isn’t necessarily so good because that well defined löyly cavity has less head to toe heat stratification and is more comfortable. However, with a lower ceiling that forces the foot bench below the top of the stones the less defined löyly cavity helps us by bringing a little bit of heat down lower around our legs and feet. So rather than cold feet we’ll perhaps just have cool feet. 🙂  

A Huum Drop, Hive or Hive Mini is an open sided mesh and also has the stones down lower so in a room with a lower ceiling should result in a more comfortable sauna than an enclosed heater or a taller mesh pillar such as a Harvia Cilandro.

My guess is that the Drop has the least defined löyly cavity and so would be best for the lowest ceilings, the Hive-Mini the next least defined and then the Hive. 

One downside is that these may produce more direct radiant heat than an enclosed style heater. Here the Drop likely produces the greatest direct radiant, the Hive-Mini next and the Hive the least. However, in many cases the Drop can be furthest away from bathers to reduce direct radiant, the Hive-Mini next and the Hive likely the closest. And then of course is stone capacity – the more the better.

So, a few trade-offs to juggle. The good news though is that I think that with a lower ceiling that any of the Huums should likely result in a better sauna experience than any alternatives that I’m aware of. 

A higher ceiling and benches is still much better but if a low ceiling can’t be avoided then a Huum may help considerably.

 

Barrels

Barrels of less than 9-10’ in diameter are inherently quite bad for sauna so there is no need to review them. More: Notes On Barrels.

 

Vendor Integrity

I really dislike people who lie or are misleading and the U.S. sauna industry is one of the most dishonest and misleading industries I’ve encountered. They make car sales folks seem like Pat Boone. Two key areas are false health claims and the number of people who can fit in a sauna. On the latter I believe that every manufacturer should include a photo of their sauna with the stated number of average American adults starting with a male (5’9” / 197lbs / 40” waist) and then alternating male/female they like. More: Quackery & Sauna Frauds

Winner: Finnleo – Finnleo makes some questionable health claims but perhaps not as outlandish or misleading as others. Their estimates for the number of people in a sauna might be tight but not unreasonable. They get some credit for not trying to foist barrels off on unsuspecting consumers but get dinged for claiming that IR is a sauna.

Harvia / Almost Heaven – Their health page is more honest than Finnleo but elsewhere on their site they make claims of weight loss and toxin release in a manner that is misleading. Their claims of how many people can fit in to their saunas is grossly misleading and dishonest. I also dislike their fake pricing with everything always ‘on sale’.

Salus / Enlighten / Sauna Place – Burn 1200 calories in 30 minutes? Do you really trust these people?

 

———————   The Reviews  ———————  

 

Finnleo Northstar 4’x4′

https://www.finnleo.com/northstar-44

Finnleo NSI 44 879x860 1

This is the only kit sauna that I would recommend. If you are limited to no larger than 4’x4’ or a 7’ high ceiling then this is not too bad of an option as a custom/DIY sauna in such limited space will have some of the same challenges. A custom/DIY can have higher benches and ceiling which would be better but this will also necessitate some tight steps that some might dislike. Many saunas in Finland and Europe of this size will have higher benches for the better sauna experience but not all.

 

Big Issues

No Ventilation – The Northstar has convective airflow for cooling the heater high-limit sensor. It lacks any ventilation for bathers. Bathers will experience high levels of CO2 which will result in their leaving the sauna from the beginnings of suffocation rather than experiencing proper heat and löyly. Bathers may also experience lightheadedness, dizziness, and other effects of hypercapnia.

This sauna will not expel humidity quickly so rather than multiple rounds of contrasting löyly this sauna will have ever increasing humidity which is not comfortable nor hygienic.

See the Ventilation article linked in the menu above for more.

Benches/Ceiling are too low – The Foot Bench should be above the top of the stones and above the lower third of the space. Bathers in the Northstar will have their feet and legs in the cold zone, experience uneven head to toe temps and cold feet and legs.

The lower bench may also develop mold and bacteria since it is unlikely to ever get hot enough (55-65°c for 20 minutes) to kill these.

Too Little Volume ? – This sauna has the minimum volume recommended for one person. While two people can squeeze in they will not have sufficient/healthy air volume. 

Limited Heat Cavity – Greater loss of heat when door opens and longer time to recover.

Heater Is Too Close to Bathers – Bathers will experience more direct radiant heat than is normally desired.

No Air Gap on rear of benches – Larger air gaps on the back of benches allow convective heat to help warm bathers backs.

 

Fixing The Northstar 4×4

Purchasers should do two things to improve the Northstar:

#1 – Add proper ventilation for bathers including a supply vent above the heater and a mechanical exhaust below the foot bench (cheated away from the heater).

#2 – Add a larger air gap to the rear of the benches by removing one slat.

 

 

Almost Heaven Saunas – Auburn / Madison / Bluestone 2-3 Person Indoor Sauna

Auburn 2-3 Person Indoor Sauna

AH Auburn 1024x1024 2x

This is perhaps best described as an American pseudo-sauna. This is not anything you are likely to see in Finland, Sweden, Germany or elsewhere outside of the U.S. as buyers there know that in this booth they will be uncomfortable, have cold feet, bad air and no löyly. 

 

Big Issues

Deceptive Advertising – This is realistically an uncomfortable one person booth, not a three person sauna.  It has physical seating for only one person and enough interior volume for only one person to breath comfortably.

But even with just one person there is only 15” of foot bench so one of their feet will be dangling or they’ll have to twist sideways for both feet to be on the too narrow foot bench.

Almost Heaven says that two can fit on the upper bench and one on the lower. At a minimum you want 24” of sitting bench (more for overweight Americans) and foot bench per person. This appears to have much less than the 48” needed for two people due to the heater. The second person will have no foot bench so their feet will be dangling in mid air, they will be pushed up against the heater so they’ll get a lot of uncomfortable direct radiant heat and unless both people are fairly thin they will be pushed up against each other.

At 20” wide the lower bench (third person) isn’t really even wide enough for a single person to sit comfortably much less a person sitting and feet of the person above. Someone on the lower bench would be sitting on someone’s feet which isn’t comfortable for either and they are almost entirely in the cold zone.

Almost Heaven should include a photo of 3 average size American adults sitting in this booth.

It would have been far better had they included a traditional foot bench as in the Finnleo Northstar or perhaps included a portion of foot bench next to this that can slide out to act as a traditional foot bench.

No Ventilation – The Auburn has convective airflow for cooling the heater high-limit sensor. It lacks any ventilation for bathers. Bathers will experience high levels of CO2 which will result in their leaving the sauna from the beginnings of suffocation rather than experiencing proper heat and löyly. Bathers may also experience lightheadedness, dizziness, and other effects of hypercapnia.

This sauna will not expel humidity quickly so rather than multiple rounds of contrasting löyly this sauna will have ever increasing humidity which is not comfortable nor hygienic.

See the Ventilation article linked in the menu above for more.

Benches/Ceiling are too low – The Foot Bench should be above the top of the stones and the sitting bench 18” above that. The bather on the upper bench of this sauna will have cold feet. The lower bench may also develop mold and bacteria since it is very unlikely to ever get hot enough (55-65°c for 20 minutes) to kill these.

Too Little Volume – Its 121 cu ft of interior volume is only enough for one person to breath safely. For two people it should have a minimum of 175 cu ft but ideally 350 cu ft. For three people 245-500 cu ft.

 

Other Issues

Too Much Glass / Too Little Wood – This will effect bather comfort as wood is hygroscopic and needed to help even out temps and humidity.

No Heat Cavity – Greater loss of heat when door opens and longer time to recover.

Not Wide Enough To Lay Down

Bench Air Gaps may be too small – This will limit proper airflow.

No Air Gap on rear of benches – Larger air gaps on the back of benches allow convective heat to help warm bathers backs.

Heater Is Too Close to Bathers – Bathers will experience more direct radiant heat that is not desirable. Bathers side facing the heater may roast.

No Floor – Some models do not have a floor.

 

 

Almost Heaven Saunas – Allegheny 6-Person Cabin Sauna

Allegheny 6-person Cabin Sauna

AH Cabin Allegheny 1024x1024 2x jpg

This is perhaps best described as an American warm room with bad air – an American pseudo-sauna. This is not anything you are likely to see in Finland, Sweden or Germany – buyers there know that in this cabin they will have cold feet, bad air and so no löyly. 

 

Big Issues

Deceptive Advertising – This is a three person sauna, not six. It has only enough interior volume for three people to breath safely and has physical seating for only three people.

Almost Heaven says that three people can fit on the upper sitting bench and three on the lower foot bench but the foot bench is only 19” deep which does not provide enough space for feet and people to sit comfortably. Even if you squeeze six people in they would be breathing each others exhaled breath and that’s not healthy nor enjoyable.

No Ventilation – The Allegheny has convective airflow for cooling the heater high-limit sensor. It lacks any ventilation for bathers. Bathers will experience high levels of CO2 which will result in their leaving the sauna from the beginnings of suffocation rather than experiencing proper heat and löyly. Bathers may also experience lightheadedness, dizziness, and other effects of hypercapnia.

This sauna will not expel humidity quickly so rather than multiple rounds of contrasting löyly this sauna will have ever increasing humidity which is not comfortable nor hygienic.

See the Ventilation article linked in the menu above for more.

Benches/Ceiling are too low – The Foot Bench should be above the top of the stones and above the lower third of the space. Bathers in the Allegheny will have their feet and legs in the cold zone, experience uneven head to toe temps and cold feet and legs.

The lower bench may also develop mold and bacteria since it is unlikely to ever get hot enough (55-65°c for 20 minutes) to kill these.

Too Little Volume – A sauna should have a minimum of 70 cubic feet per person plus an additional 35 cubic feet. Sauna builders in Scandinavia aim for twice that amount of interior volume per bather. Less volume results in high levels of CO2 (people rebreathing others exhaled breath). The Allegheny has a total of 273 cubic feet which is the minimum for three people. For six people this should be at least twice as large and ideally 4x as large.

No Vestibule/Changing/Shower Room – Door openings, particularly during colder weather, will result in greater heat loss and uncomfortably cold drafts on bathers.

Lock On The Door – There should never be a lock on the hot room door. For safety hot room doors should always be able to be opened by simply pushing on them.

 

Other Issues

Limited Heat Cavity – Greater loss of heat when door opens and longer time to recover.

Poor Ceiling Shape – This will result in unnecessary extra heat above bathers heads and the angle at the peak will decrease the convective loop in the löyly cavity resulting in greater stratification and discomfort for bathers. Making half to three-quarters of the ceiling flat would help.

Heater Is Too Close to Bathers – Bathers will experience more direct radiant heat than is normally desired.

Lack of Insulation / Thin Walls – The walls will be colder which will result in bathers having colder backs. The Allegheny will take longer to heat up and use more energy than a properly insulated sauna.

As a money saving element I do not believe this is necessarily a bad construction approach though and this is much less of a drawback than any of the big issues above. While a properly insulated sauna would certainly be better, particularly in colder climates, this sauna with proper ventilation and higher benches would likely be much better than a well insulated sauna with poor ventilation and too low of benches.

Bench Air Gaps may be too small – This will limit proper airflow.

No Air Gap on rear of benches – Larger air gaps on the back of benches allow convective heat to help warm bathers backs.

  

Fixing The Allegheny

In order of importance to achieving a proper sauna experience:

#1 – Add proper ventilation for bathers including a supply vent above the heater (wood & electric) and a mechanical exhaust below the foot bench (electric).

#2 – Add 18-24” to the overall height and raise the benches. This will also create a better heat cavity.

#3 – Add a vestibule and remove the lock from the hot room door. Or, include the capability for a vestibule to be easily added at a later date.

#4 – Add a flat segment to the ceiling.

#5 – Add a larger air gap to the rear of the benches and possibly increase the air gaps of the benches themselves if too small.

With these changes I believe this would be a relatively good sauna for two people and occasionally three or maybe four, particularly for milder climates that don’t get too cold.

Almost Heaven could plan this so that they can offer a vestibule/changing/shower as add-on kits that can be added at a later date. And similarly a porch (with roof) add-on so that eventually the owner could have a proper Finnish sauna with a hot room, changing room, shower and covered porch. An option for adding a window or two in the sauna hot room would be good.

 

Almost Heaven – Appalachia 6-person Sauna

Also: Salus Olympia 6-person sauna.

Salus tr ca c6 ah002 salus 6 person cabin sauna outside 2

 

This is a very cute cabin but will make for a quite poor sauna. They do get credit for having a vestibule and porch!

The Issues

Deceptive Advertising – This is a three person sauna, not six. It has only enough interior volume for three people to breath safely and has physical seating for only three people. With three people sitting on the sitting bench and feet on the foot bench there will not be space for three more people to sit comfortably on the lower foot bench. 

No Ventilation – This appears to have only convective airflow for the heater and lacks any fresh air ventilation for bathers. Bathers will experience high levels of CO2 which will result in their leaving the sauna from the beginnings of suffocation rather than experiencing proper heat and löyly. Bathers may also experience lightheadedness, dizziness, and other effects of hypercapnia.

This sauna will not expel humidity quickly so rather than multiple rounds of enjoyable contrasting löyly this sauna will have ever increasing humidity which is not comfortable nor hygienic.

See the Ventilation article linked in the menu above for more.

Benches/Ceiling are too low – The Foot Bench should be above the top of the stones / lower third. Bathers in the Appalachia will have their feet and legs in the cold zone, experience uneven head to toe temps and cold feet and legs.

The lower bench may also develop mold and bacteria since it is very unlikely to ever get hot enough (55-65°c for 20 minutes) to kill these.

Too Little Volume – A sauna should have a minimum of 2 m³ (70 cubic feet) per person plus an additional 1 m³ (35 cubic feet) for the stove. Sauna builders in Scandinavia aim for twice that amount of interior volume per bather. Less volume results in high levels of CO2 (people rebreathing others exhaled breath). The Appalachia has a total of 7.2 m³ which is the minimum for three people. For the claimed six people this should be at least twice as large and ideally 4x as large.

Poor Ceiling Shape – The bulk of the heat will be up above the side opposite bathers. This shape will also reduce or likely totally eliminate the critical upper convective loop so this sauna lacks a löyly cavity resulting in greater stratification and discomfort for bathers. The ceiling should be generally flat and about 260cm above the floor so that the foot bench can be above the top of the stones.

Heater Is Too Close to Bathers – Bathers will experience more direct radiant heat than is desired.

Limited Heat Cavity – Greater loss of heat when door opens and longer time to recover.

Lack of Insulation / Thin Walls – The walls will be colder which will result in bathers having colder backs. The Olympia will take longer to heat up and use more energy than a properly insulated sauna.

However, as a money saving element I do not believe this is necessarily a bad construction approach and this is much less of a drawback than any of the bigger issues above. While a properly insulated sauna would certainly be better, particularly in colder climates, this sauna with proper ventilation and higher benches would likely be much better than a well insulated sauna with poor ventilation and too low of benches.

Bench Air Gaps may be too small – This will limit proper airflow.

No Air Gap on rear of benches – Larger air gaps on the back of benches allow convective heat to help warm bathers backs.  

Fixing The Appalachia

In approximate order of importance to achieving a proper sauna experience:

#1 – Add proper ventilation for bathers including an adjustable fresh air supply vent above the heater (wood & electric) and a mechanical exhaust below the foot bench (electric).

#2 – Increase the ceiling height so that the foot bench is above the top of the stones. This will also create a better heat cavity.

#3 – Flatten the ceiling. Very slightly peaked or coved works well (with the peak no more than about 20cm above the top of the walls) but not as steep as this one nor one-sided as this one. While not ideal, even just adding a slope to the door/heater side of the ceiling would help.

#4 – Increase the depth so that bathers are a little further back from the stove or include a baffle wall by the stove to reduce direct radiant heat on bathers.

#5 – Add a larger air gap to the rear of the benches and possibly increase the air gaps of the benches themselves if too small.

With these changes I believe this would be a relatively good sauna for two or three people, particularly for milder climates that don’t get too cold. 

 

 

Sunray – Baldwin 2-Person Sauna

Sunray Baldwin 2-Person Traditional Finnish Sauna

 

Sunray Baldwin

 

This is not really a sauna at all, much less a ‘Traditional Finnish Sauna’ as advertised. According to the Sunray documentation it can only get to a maximum temp of 80°c (176°f) which is below the 80-105°c recommended by the Finnish Sauna Society and the International Sauna Association. But worse, due to the extremely low bench and being so much below the ceiling, the bather will experience much lower temps. All of the heat will be above their heads and rather than the 80-105°c temps recommended the bather will be closer to about 60°c at best.

 

Big Issues

Deceptive Advertising – This is a one person sauna, not two. It does not have the volume nor seating capacity for more than one. The bench is wide enough for two people but the heater is in the way of a second person.

No Ventilation – The Baldwin has convective airflow for cooling the heater high-limit sensor. It lacks any ventilation for bathers. The bather will experience high levels of CO2 which will result in their leaving the sauna from the beginnings of suffocation rather than experiencing proper heat and löyly. Bathers may also experience lightheadedness, dizziness, and other effects of hypercapnia.

This sauna will not expel humidity quickly so rather than multiple rounds of contrasting löyly this sauna will have ever increasing humidity which is not comfortable nor hygienic.

See the Ventilation article linked in the menu above for more.

Bench is much too low – The Foot Bench (floor in this case) should be above the top of the stones and the sitting bench at least 18” above that. Here they are at least 22” too low as well as far below the ceiling. The bather will have their entire lower body in the cold zone, experience overall low temps, uneven head to toe temps and cold lower body.

The floor may also develop mold and bacteria since it is very unlikely to ever get hot enough (55-65°c for 20 minutes) to kill these.

Too Little Volume – A sauna should have a minimum of 70 cubic feet per person plus an additional 35 cubic feet. This sauna barely has enough volume for one person and not enough for the advertised two people. 

Other Issues

Limited Heat Cavity – Greater loss of heat when door opens and longer time to recover.

Bench Air Gaps may be too small or non-existent – This will limit proper airflow and be uncomfortable.

No Air Gap on rear of benches – Larger air gaps on the back of benches allow convective heat to help warm bathers backs.

Heater Is Too Close to Bathers – Bathers will experience more direct radiant heat than is normally desired. 

 

 

 

Dundalk Luna (CTC22LU)

Canadian Timber Luna CTC22LU

Dundalk CTC22LUa

NOTE: I wrote this review based on the specifications on their web page. I’ve since learned that these specifications are inaccurate and misleading – that the interior of the sauna is only 204cm high and not 246cm as their drawings indicate.

This is perhaps the most consumer fixable kit sauna available in North America and the only one I’d recommend (with reservations). Building your own will still result in a much better sauna experience though and I still recommend that until kit sauna builders in North America figure out how to build saunas correctly.

Dundalk’s other saunas are quite bad and their Mini Pod downright awful and perhaps the rare case of something being worse than a barrel indicating that Dundalk and Leisurecraft do not understand sauna but here perhaps accidentally produced something fixable.

This sauna can seat 3 people and will have about 100 cubic feet of volume per person which is good. The sitting bench is long enough for someone to lay on but too narrow.

Dundalk

Dundalk 

 

Big Issues

No Ventilation – The Luna has convective airflow for cooling the heater high-limit sensor. It lacks any ventilation for bathers. Bathers will experience high levels of CO2 which will result in their leaving the sauna from the beginnings of suffocation rather than experiencing proper heat and löyly. Bathers may also experience lightheadedness, dizziness, and other effects of hypercapnia.

This sauna will not expel humidity quickly so rather than multiple rounds of contrasting löyly this sauna will have ever increasing humidity which is not comfortable nor hygienic.

See the Ventilation article linked in the menu above for more.

Benches/Ceiling are much too low – The Foot Bench should be above the top of the stones. Bathers in the Luna will have their feet and legs in the cold zone, experience uneven head to toe temps and cold feet and legs. The benches are too low relative to the ceiling so all of the heat will be above bather’s heads.

The lower bench may also develop mold and bacteria since it is very unlikely to ever get hot enough (55-65°c for 20 minutes) to kill these.

No Vestibule/Changing Room – Door openings, particularly during colder weather, will result in greater heat loss and uncomfortably cold drafts on bathers. 

Limited Heat Cavity – Greater loss of heat when door opens and longer time to recover.

Heater Is Too Close to Bathers – Bathers will experience more direct radiant heat than is normally desired.

Lack of Insulation / Thin Walls – The walls will be colder which will result in bathers having colder backs. The Luna will take longer to heat up and use more energy than a properly insulated sauna.

As a money saving element I do not believe this is necessarily a bad construction approach though and this is much less of a drawback than any of the bigger issues above. While a properly insulated sauna would certainly be better, particularly in colder climates, this sauna with proper ventilation and higher benches would likely be much better than a well insulated sauna with poor ventilation and too low of benches.

Bench Air Gaps appear too small – This will limit proper airflow.

No Air Gap on rear of benches – Larger air gaps on the back of benches allow convective heat to help warm bathers backs.

Roof Leak? – The design of the flat roof looks like it could result in leaks. Extending the EDPM beyond all edges could possibly help.

Cedar – This wood can be quite strong fragrance which can detract from the sauna experience. Sauna’s in Finland and elsewhere outside of North America use less fragrant wood like spruce.

 

Fixing The Luna

The Luna has one advantage – interior height. A consumer can likely fix the worst of the problems (#’s 1-4 below and if handy 5 & 6) and have a relatively good sauna. 

#1 – Add proper ventilation (50-80 actual CFM) including a supply vent above the heater and an electric powered mechanical exhaust below the foot bench. See Sauna Ventilation in top menu. 

#2 – Raise the benches. The sitting bench should be 100-122 cm (42-48”) below the ceiling. Here I’d recommend setting it at 44” (112 cm) below or perhaps a bit more if taller people will be using it. A step or wood stool should be added for easier access to the benches.

#3 – Make the upper bench 24-26” deep so that someone can more comfortably lay on it.  The lower bench can be 18-20”.  

#4 – Narrower bench boards, larger air gaps and an air gap on the back of the bench would help.

#5 – Lower the height of the door to create a larger heat cavity.

#6 – Add a vestibule. Or, include the capability for a vestibule to be easily added at a later date.

#7 – Offer a non-cedar option.

These changes will vastly improve this unit and I believe this would be a relatively good sauna for three people, particularly for milder climates that don’t get too cold.