The old Sauna at Podunk had two rooms: a small dressing room and the larger hot room. The Old Nippa stove sat between them embedded in a masonry wall. Sitting on the benches we stared at the business end of the stove with its pile of rocks and the stove was tended from the dressing room.
This arrangement always made sense to me and is how I have been building my saunas for 30 years. I learned to weld in art school and set up my own studio soon after. Ozzie would send people my way for their stove repairs. After seeing how other stoves failed, I designed and started making my own stoves using much heavier plate on the top, where the heat would soften the thinner steel and typically lead to collapse under the weight of the rocks. I also kept to the external feed (thru-wall) and designed my stoves to be fired exclusively that way. As kids, we loved to pretend we could speak Finnish by stretching vowels and consonants together and making up Finnish sounding nicknames for each other. I called my stove the Lämpimämpi by combining Lemp and Memp. Finns will chuckle at this because it translates to: “warmer”.
I called my stove the Lämpimämpi by combining Lemp and Memp. Finns will chuckle at this because it translates to: “warmer”.
There are so many reasons for the external feed (thru-wall):
• The fire-tending, and ash debris are kept out of the hot room and you don’t have to tramp in and out with your boots on to tend the fire.
• Venting a small space can be complicated; a sauna stove requires significant combustion air which can create drafts or, worse, rob oxygen from the hot room. The external feed draws air from the dressing room or outside.
• Any stove front requires 36 inches of clearance to combustibles in front of it. This can’t be mitigated by heat shields. This severely limits the layout of the hot room. However, it is easy to get 3 feet in front of the stove in the dressing room.
• Any stove also requires a noncombustible hearth (stone) 18” in front of the stove. Hot ash and coals falling out the stove are a major source of fires. In a crowded and dark sauna room these hot coals can easily be overlooked, fall under duck boards, etc.
•A flickering flame to look at may be romantic but it is the soft heat off the rocks you want, not the searing radiant heat you get from sitting in front of a blazing fire. Typically, the fire may be almost out by the time the sauna is ready. The rocks should be the focal point. Also, following the 36-inch rule above, you can’t have the stove front facing the bathers, unless the sauna is excessively big.
• If you are providing a sauna experience for others, you can discreetly tend the fire without interrupting the bathers or invading their privacy.
•The external feed stove heats the dressing room just enough so that you can hang out and watch the fire while the sauna heats up.
Installing the external feed may seem daunting but it is not that difficult. A firewall with the requisite size opening will be required. This can be solid masonry, which will add thermal mass (and take longer to heat the sauna) or a hollow insulated firewall with steel studs and cement board, and tile or stone facing, or stucco over metal lathe (which I typically use). A metal sleeve will be provided with the stove to dress up this opening and provide further heat shielding. My Lämpimämpi stove has an integrated heat shield / rock basket that works with the wall opening so that fresh air coming in is heated directly by the stove and directed over the rocks, which is an advantage over simply having the rocks sit on top inside a steel box. As with any installation, all listed clearances need to be adhered to, but with this method, the stove will take up less space in the hot room and make for a cleaner presentation. For your next sauna, consider this traditional way of building it.
I have always been fascinated by fire. There is a mystery to it that even science cannot unravel. It is more like the fourth state of matter—plasma—than the familiar trio of liquid, gas and solid. I have played with and studied fire since I was a kid, sometimes barely avoiding serious trouble, other times under the guidance of elders, like in Boy Scouts where we boiled a quart of water in five minutes during fire-building competitions. As I grew older, burning wood became a way to heat our home. Wood cutting and splitting became not only a chore but a workout and a way to get my angst out with each strike of the axe.
After I learned metalworking in art school, I started to apply my skills to making wood stoves and thinking about what happens inside of a stove- the mysterious process where tons of wood are reduced to a small amount of ash, carbon dioxide, particulate, and other emissions that are carried away by the wind. The heat is from the atomic bonds of carbon molecules breaking, turning matter back into the energy of the sun that formed those molecules. There is something seductively simple in that balance of carbon in/carbon out, but, as we now know, there is also something deviously complicated about the carbon cycle. I have warmed myself with wood heat over the years in my home, shop, and sauna; each time I light a fire there is still this fascination and allure to the flames that draws me to it and perhaps blinds me to greater issues.
In the past 50 years, wood stoves have gone through several changes. Initially they were simply boxes with a loose-fitting door and a chimney—like the Ben Franklin stove. These stoves burned uncontrollably and inefficiently and needed constant feeding. Later, air-tightness became a thing: dampers were dialed in, rope caulk was added to the doors, and the fires were slowed down so they could burn all night. But as the fire burner longer and cooler, not all the organic matter was burned— more went up the chimney. Flammable wood gasses called creosote condensed on the cool sides of the chimney, building up thick tar-like layers. Eventually that caught on fire, sometimes taking the whole house with it. In the 70’s we went though the energy crises and wood stoves became a very popular way to deal with spiraling oil cost. The 70’s also saw the birth of the environmental movement and the EPA. The EPA stepped in as did Underwriter’s Laboratory (UL). Stoves had to be made safer and cleaner burning. Expensive Catalytic convertors—like on your car—were added to the stove outlet, to capture some of the nasty stuff. But neophytes, in their craze to burn wood, skipped the all-important step of letting firewood dry at least 2 years. The converters clogged up. The cats were dropped, and the focus turned to better engineering. Stoves are now designed with all kinds of baffles to get the wood to burn cleanly; they are complicated affairs, and many don’t work that great- they certainly don’t burn all night, or, as I used to do with mine, burn non-stop, all winter.
But sauna stoves are a different beast. Since they are “occasional use only” (and only one is UL listed) they are, thankfully, technically EPA exempt. But still, I don’t want to be “that guy” that smokes out the neighborhood every time I light my sauna—especially since this past summer when we all got a taste of the Smoke Armageddon. So, despite my years of wood-burning experience, I am always trying to tweak the process and learn the idiosyncrasies of my stove. Every stove fires differently and even a familiar stove can rebel on you when the wind changes or you when move the sauna. When I light mine, I know it will smoke some; my goal is always to get it burning hot as fast as possible so the smoke will be minimal.
The three sides of the fire triangle are heat, fuel, and oxygen. A perfect balance gives a cleaner burn.
You can easily adjust the fuel and air but not so much, the heat. The heat in a wood stove comes from the fire itself, so, you need to get the stove very hot, as quickly as possible, to achieve a good balance. Wood emits gas when is heated above a certain point in a reduced atmosphere; this gas will burn cleaner than the wood itself. If you get your stove so hot that the wood gas burns before the wood, it will burn cleanly. There are cars designed to run on wood gas: a heated tank of wood chips creates the gas that runs the engine. Most stoves have a baffle or two and an upper chamber where the hot gasses will hopefully combust when mixed with additional air; the real heat is at the top of stove, before it exits the flue. In my Lämpimämpi stove, the top plate, that the rocks sit on, is 3/8” steel. I will get this steel glowing a dull cherry red (about 1300°F). Any gasses passing through this chamber will be burned. But until the upper chamber is hot, gasses and particulate will escape up the chimney and the sauna will smoke. Having a brick-lined fire chamber will help the fire get hotter faster. Wet cool days will make it worse as will a down-draft caused by the sauna being in the lee of nearby trees or structures. Wet wood doesn’t help either.
Up until this week my process has been to get a small fire going briskly, with the ash drawer open, and stove door open until it starts to roar (I have an external feed, so no worries about embers falling out.) Then I add larger sticks in one or two loadings until I fill the fire chamber (nothing bigger than my arm–scrap 2×4’s are perfect) topping it with one or two small hardwood logs. The problem is, when I add the fresh wood on top of the fire, there is a period of incomplete combustion as the wood heats up, and the stove smokes a lot. If the wind is wrong, my neighbors will get smoked out. I tinker with the ash drawer or open the stove door to blast in more air until the smoke clears (another advantage of an external feed: I can watch the chimney.) I can add more air to balance the fuel, but I can’t add more heat. Think of it like the carburetor on an old car. Too open, it won’t run well, too closed, it sputters and smokes and clogs the engine. Not enough heat, and it won’t burn well either. I try to find the sweet spot. Unlike a wood stove in a house, I’m not worried about things getting too hot- better than too cool. It’s not uncommon for my stove pipe to glow red for a while—that’s ok, because I know my installation is safe.
Recently, after reading an online post, I tried a new way to fire the stove (yes, old dogs can learn new tricks): from the top down! I load up the stove with larger sticks at the bottom, then smaller, with short sticks crisscrossing between them. Then on top of this stack I put the wads of newspaper with a handful of kindling and light that. The fire immediately starts heating the baffle and upper chamber as the fire slowly works it way down. This way the flames aren’t cooking the larger sticks before they are ready to burn. This solves the too much wood/not enough heat problem. Amazingly it only takes 5-10 minutes for the fire to reach the bottom and a hot bed of coals forms quickly. I leave the ash drawer slightly for twenty minutes and then add more wood. After that you can’t even see any smoke. When we take our sauna to one of the local parks, we can be clandestine; with no tell-tale smoke; passersby have no idea that our sauna is cranking hot inside.
I know there is a whole argument for decreasing our carbon footprint as much as possible and not burning any wood; but there is an opposing argument that says we need to maintain our ties to nature to want to save it. Controlling fire is not only as old as mankind but one of our defining traits.
Without getting into the debate, which I’ll admit I don’t lose sleep over, I will admit that I don’t want to be “that guy”. I want to remain sensitive to others and burn my stove as cleanly as I can. Learning how to master the art of fire building is one small step to take if I am going to cling to tradition and enjoy a really smokin’ hot sauna.
In order to save it, the old Sauna at Podunk had to be taken down. The squirrels had taken over and filled the dressing room with a cache of nuts. The building was slowly sinking into the earth and the safety of the chimney, a heavy cast cement affair supported in the ceiling by a rusty homemade contraption, was questionable. The gaping mouth of stove door was rusted open in a permanent state of whoa. If this sauna was ever to make löyly again, work would have to be done. So, a month ago, after careful consideration and much debate, Scarlet and I joined members of the Heila family for a day of deconstruction.
As you may recall from earlier posts, (Sauna Time, Sauna Ritual,Homecoming, Back to Podunk) this is the 90 year-old sauna where many of us locals were initiated in the joys of sauna during the heyday of the 70’s when the Podunk Ski Center was a mecca for Nordic Skiing and all things Finnish. Its simple rustic character, which addressed the basic functionality of the sauna with what I call Finnish pragmatism, is the inspiration behind much of my sauna building. The demolition would give me the chance to dissect it and uncover some the secrets of its original design.
We always thought it was the perfect sauna: hot but airy, it made good löyly, and was roomy enough for an intimate crowd of 8.
What I did not know was how the materials related to its function: how well it heat up, how it held a good Löyly and never felt stuffy, and why it never burned down. Aesthetics aside, these are essential components to a good functioning sauna. We often debated whether it had any insulation at all, so I was especially curious about that.
It was a drizzly morning with a chill to the air; ironically, a perfect day for sauna. Our plan was to document the existing structure and take it down methodically, saving what we could and carting the rest away. Eventually the structure will be rebuilt, as close to the existing as possible, on the same site. We proceeded quickly, each of us attacking an area. Beloved details like the doors and little shelves in the dressing room were labeled, wrapped and carefully stored. The barn board siding was carefully removed board by board, and the whole front facade was Sawzalled off and preserved. As the layers were peeled back, we discovered not only that there had been several incarnations to the structure but we uncovered the answers to some of the questions I had been pondering. There were several surprises.
As the walls were removed from the outside in, we uncovered many layers and each wall was different. On the east wall, under the vertical reclaimed barn boards (installed in the 1970’s?) was a layer of Inselbric, the ubiquitous and horribly ugly asphalt siding that was used starting in the 1930’s. It was easy to use and durable and is still found on many “economy” (or as my Dad would call it: “Early American Poverty”) style homes dating between 1930 and 1960, until aluminum siding became popular. This was over a layer of horizontal 1×6 pine boards, loosely spaced, which went around most of the building. Under this was the big surprise: flattened cardboard boxes, several layers deep, between rough sawn vertical framing members about two feet on center.
The cardboard was in good shape and the labels were easily read: cereal case boxes from Wheaties, Corn Flakes and others. This was the insulation we all wondered about!
A web search of the logo style led to verification of the 1935 date of construction. Interspersed with the cardboard were vertical boards with no apparent purpose. Was this to add thermal mass to the walls? The interior surface was initially all Beaverboard, an early fiber board, which was covered with a thin veneer of plaster (real plaster, not joint compound) which was painted. This was akin to the plaster and tile block sauna of Van Buskirk Gulf I wrote about in a previous blog. This would have provided a vapor resistant barrier that would have held the Löyly steam for the right amount of time. Later, in the 1970’s, this was covered with 1×6 tongue and groove knotty pine. With our current obsession over cedar (or other wood) interior walls wonder if a more authentic sauna might be simply plaster with wooden benches and back rests? The plaster and paint layers (probably lead) were vapor semi-impermeable and thus capable of holding some of the moisture. Surely all the outer layers in the walls were breathable, that is, allowing vapor to easily escape and not collect as condensation, which is a very important consideration in any kind of construction. But I did notice one corner post had signs of severe rot. Did the plaster layer crack here and allow moisture to saturate the wood, setting the stage for a colony of carpenter ants to move in?
I also noticed that, other than the entire building sinking into the earth, the walls were structurally sound. So much so that when Tom hooked up the tractor to pull the north wall off, the whole remaining building (already missing its east and south wall) simple hopped along the foundation slab behind the tractor, taking the chimney with it and sending me into a fit of laughter. All those random layers of heavy boards were keeping things together. It’s not a recommended practice, but sometimes just heaping layers of wood into a structure creates enough redundancy to make it solid. I prefer the more efficient approach of building more with less.
The ceiling was like the walls, with plastered Beaverboard covered by pine. The tiny attic space was filled with a layer of cellulose interspersed with rodent droppings, walnuts, empty boxes of rat poison and a few old bottles, which probably once contained hooch. One was verified as being from 1938 by its unique design. Probably teenagers hiding their stash after a sauna; but, quite possibly, offerings to the sauna Gods to protect it from burning down.
As for fire safety, it was a miracle that the sauna never did burn down. There was a lot of charred wood throughout the attic, especially around the iron chimney supports.
Again, there were a lot of heavy boards, which seemed to have no structural significance, perhaps only adding thermal mass or insulation. The roof rafters were so heavy and the roof so strong that after it was lying on the ground like a low pup-tent, Tom had to drive the tractor over it to break it apart. The metal standing seam roof, with its many coats of black tar, was in surprisingly good shape, but leakage was occurring where the heavy, cast refractory cement chimney penetrated it. The stove below, welded by me in the 1990’s, was so rusted it was deemed to be scrap.
The cement floor had sloped to a drain but was cracked and broken. The original cement pour seemed hodgepodge and lacked any re-bar. Woodchucks had tunneled voids underneath it. The drain allowed for bathing— something the early Finnish farmers needed as the house probably lacked plumbing; bathing, to me, is an essential part of the sauna experience; that function of the sauna informs my designs. The floor will be replaced with an edge- thickened slab as the foundation; with a solid gravel base over undisturbed earth and with steel reinforcement.
The one component that perhaps was a factor in why the sauna felt so good was all the brick work around the stove, which was fired through the dressing room wall—a traditional design I frequently use. This added about a thousand pounds of thermal mass around the stove. Thermal mass holds the heat and radiates it back into the room but also means it will take longer to heat up. I typically use a lightweight fire wall so the sauna will heat quickly and to lessen the load on the building structure, but perhaps I should re-think that and revert to the solid masonry I started building with in the ‘90s. Ironically, the brick work at Podunk was added in the 70’s. The old Finns around here commonly relied on asbestos board for fire protection.
By the end of the day, we had a pile of barn boards and other parts stacked and labeled in the old ski lodge, and a dumpster overflowed with the rest. Although most of the sauna was discarded, the lessons learned will live on in the saunas I continue to build. Next year, we will rebuild Podunk with modern efficiency but in the same basic footprint as the original. Hopefully the entire facade will be replaced and the lilac tree where the sauna bell hung replanted. We’ll probably skip the lead paint and asbestos board and use a modern, UL listed chimney support in lieu of the home-made rig that was there. Fire safety will be based on science, not luck. Cedar over foil (with an air gap!) will line the walls and the functionality will be the same, and hopefully, better.
Family and friends will gather there to sweat and bathe and run naked to the creek for generations to come.
Traveling with one of our mobile saunas to the lake and delivering to new owners.
We have been building mobile saunas for the past 10 years! and because of their growing popularity and versatility, they now make up most of our business. Each unit is still handcrafted with many layers of details. The owners each get a unique product tailored to their specifications. It’s also an easy way to avoid zoning and permitting restrictions while avoiding the hassles of a site-built project. Investing in your dream sauna makes more sense if you know you can take it with you!
We hear from our customers all the time that their friends, family, and neighbors are as excited as they are to have a sauna!
mobile sauna, wood-fired sauna on a trailer
For many people, owning a sauna feels like a bare necessity during the winter months!
This recent sauna build is just steps from the owner’s historic New England homestead. Our saunas are designed to blend in with the home and environment. The classic details of this historic house are elegant rustic with dramatic rock outcroppings and a fire pit, making for a perfect gathering spot.Our wood-fired mobile saunas travel well and can be parked in beautiful placesScarlet by the lake ready for a cold plunge
Having a sauna at home is a life upgrade that is low-maintenance.
Our 5×8 ft Mobile Sauna parked in town with 100 gallon cold plunge tank.Interior of our larger mobile sauna. Our saunas can get as hot as you like with a large pile of rocks. We aim for 100°C / 212°F We build many mobile saunas in our shop in Ithaca, NY. Working in our 3000 square foot shop is more efficient than building on-site.Two sizes of mobile Saunas on display at our shop in Ithaca, NY
We offer building plans for DIY sauna builders or your local builder for one-time usage only. Thanks to our valued sauna plan customers, and the growing popularity of DIY sauna building, we have taken the opportunity to launch our new & improved mobile sauna building plans! Our sauna plans are 50+ pages and include detailed notes, drawings, photos, and material lists for a wood-fired 5’x8’/6.5’x10′. If you are thinking about purchasing our plans or building a sauna, we offer you an opportunity to build your own sauna using construction plans. Rob Licht has developed the best practices of sauna building with 30+ years of experience.
Mobile Sauna Interior with the Lämpimämpi sauna stove, tiered benches and large window with a beautiful view of the fall foliage. Wood-fired from the outsideLämpimämpi sauna stoveStick hardware by Rob Licht
Stay posted on the latest Finnish-blue mobile sauna outings on Instagram @saunasbyrob and facebook @custom-saunas We’ll be using this one for pop-up and promotional events in the Finger Lakes region of New York State to share our saunas and promote sauna culture.
PRESS INQUIRIES: Contact Scarlet at contact@roblichtcustomsaunas.com
We just finished this sweet sauna: an eight by eighteen-foot building with an ample dressing room, large hot room, and wood storage on one end, all on a 12×20 raised deck. The site is near a cabin and a nice pond, all on a remote hilltop in the Finger Lakes.
The design and the craftsmanship were driven by the concept: a weekend retreat from the bustle of life, removed from technology and the stress of the 21st century. Nestled in nature, the sauna has windows to let the light in and open the view to the woods and pond.
We kept it simple, yet well crafted and elegant. The sauna functions as a centerpiece to the family gathering place and also serves as the bath house—since they are eschewing modern conveniences like running water.
Henry David Thoreau may have had his pond, but what he really needed was a sauna.
