Fire, like sauna, is a keystone of my life. There is a mystery to fire 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 when my troopmates and I boiled a quart of water in five minutes during a fire-building competition. As I grew to an adult, burning wood became a way to heat our family 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 a stove—the mysterious process where tons of fuel wood are reduced to a small amount of ash, carbon dioxide, particulate, and other emissions, carried away by the wind. The heat is generated when the atomic bonds of carbon molecules break, 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 a allure to the flames that draw me to them, calms my mind, and perhaps blinds me to greater issues.
In the past fifty years, wood stove technology has gone through several changes. Initially, stoves 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, airtightness 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 while the fire burned longer and cooler, not all the organic matter was combusted—more went up the chimney. Flammable wood gases called creosote condensed on the cool sides of flu pipes and chimneys, building up thick tar-like layers. Eventually, that compound would catch fire, sometimes taking the whole house with it.
In the ‘70s, the nation endured an energy crisis, and wood stoves became a very popular way to deal with the spiraling cost of oil. The ‘70s also saw the birth of the environmental movement and the Environmental Protection Agency (EPA). The EPA stepped in to regulate the developments in wood heating as did Underwriter’s Laboratory (UL). Stoves had to be made safer and cleaner burning. Expensive catalytic converters—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 two 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 different beasts. Since they are “occasional use only” (only one model is UL listed) they are, thankfully, EPA exempt. Technically. But still, I don’t want to be that guy who 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 coming down from Canada’s forest fires. So, despite my years of wood-burning experience, I continue to tweak the process and learn the idiosyncrasies of my stove. Every stove fires differently, and even a familiar stove can rebel when the wind changes or when a sauna is moved. When I light mine, I know it will smoke some. My goal is always to get it burning hot as fast as possible so combustion is near complete and 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 the heat, not so much. 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. Above a certain temperature, wood emits gas when heated 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 to power the engine.)
Most stoves have a baffle or two and an upper chamber where the hot gases will hopefully combust when mixed with additional air. The real heat is at the top of stove, before it exits the flu. 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 gas passing through this chamber will be burned. But until the upper chamber is hot, gases and particulates 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 2×4s 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, but 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 thicker sticks at the bottom, then smaller, with short sticks crisscrossing between them. Then on top of this stack I put 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 its 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 five to ten minutes for the fire to reach the bottom, and a hot bed of coals forms quickly. I leave the ash drawer open slightly for twenty minutes and then add more wood. After that, I can’t 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 humankind but one of humanity’s defining traits.
Without getting into the debate, which I don’t lose sleep over, I admit again 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.
If you look Podunk up in the dictionary, it will tell you it is a hypothetical or insignificant town.
The folks who live there think otherwise. In reality, Podunk is a place name on the map, the location just a short ski south of Trumansburg, New York, where I grew up. The smattering of residents, will all tell you that Podunk is very real and very significant.
In the 1960s, Ozzie Heila settled there with his family on an old farmstead established by an even older Finn who first built his sauna (above) before the house in the 1930s. It is also where I learned all the important things in life. In the 1970s I spent countless winter hours there at the ski center that Ozzie established, becoming a damn good Nordic skier and developing a life-long passion for the sport.
In the summers, I explored the creek with his son my good friend Daniel and learned the value of immersing one’s self in nature. Daniel’s mother, Ethel, was my art teacher in middle school; she helped me become the artist I am today, and we still have wonderful conversations about color theory and art composition. The sauna was the heart of the complex of dated farm buildings; there I learned to channel my need to experience extremes into something healthy and life affirming. We loved going from the hot to the cold.
Jumping in the creek in the dead of winter after a searing round in the sauna, we felt more alive than ever. That feeling has never died; each cold plunge I take during sauna takes me back to that creek.
Today, Daniel and his family were back in the area and we went to Podunk to visit the old homestead once again. This time we took our Finnish Blue mobile sauna and parked it next to the ramshackle old sauna, which is now defunct and awaiting a rebirth. Of course, many things have changed in that memorable place. The trees have grown huge or have died; the old purple Lilac, with the rusty sauna bell hanging from its branches, is gone and the brush has been cleared away from the old sauna, revealing the sagging bones of the century-old structure. But the building itself is as recognizable as the last day I took a sauna there about twenty-five years ago. The inside is a sadder story. It turns out that squirrels like the sauna too, and they have made it their own. In an expression of horror at the mess, the Lämpimämpi stove I welded up for Ozzie in the 90s sits with it’s mouth rusted wide open.
The path through the field to the creek is the same but with a detour to the left towards a new dipping hole: a makeshift stone bathtub—with a strategically placed rock to help keep your butt moored—in the midst of the rushing current. The run down to the creek had an awkward familiarity: running all out before cooling off while maintaining stable footing. Still a challenge. And the sensation! Whoops and hollers of twelve-year-old boys came out of us as we braved the icy April stream.
Real or not, Podunk is the same as it will always be. What are memories but unreal fragments of experience in our minds, ready to be stirred up by whirling waters in a cold stream or by the exhilarating steam of a sauna?
The old next to the new will always appear old, until we make it new again and live our lives to the fullest, with no regrets, in the now, and with dreams, not of memories, but of tomorrows.
New sauna and parked it next to the old sauna near the creek.
Traveling with one of our mobile saunas to the lake and delivering to new owners.
We have been building mobile saunas for the past ten 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 and 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 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 places.Scarlet by the lake ready for a cold plunge
Having a sauna at home is a low maintenance life upgrade.
Our 5’x8′ mobile sauna parked in town with 100 gal. cold plunge tank.Interior of our larger mobile sauna. With a large pile of rocks, our saunas can get as hot as you like. We aim for 212° F (100° C)We build many mobile saunas in our shop in Ithaca, NY. Working in our 3000 sq. ft. 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 fifty plus pages and include detailed notes, drawings, photos, and material lists for a wood-fired, 5’x8’/6.5’x10′ build. 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 thirty plus years of experience.
“The blue of our lakes and the white snow of our winters.”
—Zachris Topelius, poet
Colors used on this mobile sauna were inspired by the Finnish flag.
Our Finnish-Blue Sauna is in the News: Read Our Story > Stay posted on the latest Finnish-blue mobile sauna outings on Instagram @saunasbyrob and facebook @custom-saunas We will use this sauna for pop-up and promotional events in the Finger Lakes region of New York State to showcase our saunas and promote sauna culture.
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 outside.Lämpimämpi sauna stove.Stick hardware by Rob Licht.
The landscape of Upstate NY is punctuated by the rural agrarian architecture typical of an area rooted in nineteenth-century traditions. Massive old barns reign supreme and are typically surrounded by a cluster of smaller accessory buildings: smaller barns and equipment sheds, dairies, smokehouses, and occasionally, if one looks hard enough, a sauna. Sadly, many wood sided buildings have either burned or fallen into abstract destructions of their formal selves. Their replacements—metal-sided Morton buildings and giant fabric-covered hoop structures—are strictly utilitarian and lack the romantic appeal of the old barns. It is the nineteenth century aesthetics that inspire the creative in me.
When I was an aspiring young artist, old barns were often my subject matter. My father and I would drive through in the country and stop to draw landscapes with a barn as the focal point.
Now, when I build my saunas, the vernacular of old farm structures is never out of my mind. In particular, it is the older simple gable roof structures that draw me in, rather than the more efficient gambrel roof. There is something pleasing about the simple geometry and the formal balance in earlier barns. When additions were made, they typically resulted in a hodge podge of shapes, and the formal symmetry was lost.
Rob stands next to an old saw blade that waits to be refurbished.Rough cut 1″x12′ pine for sauna exterior.
The barns were typically sided with local pine, attached vertically with green boards nailed closely but with gaps that would open as the wood dried. These gaps were often covered with narrow battens. These pieces were nailed so that the siding boards could shrink and swell. This is the beauty of board and batten siding: it takes into account that the wood is alive and not a fixed entity. It is this board and batten technique, or variations of it, like reverse board and batten or vertical shiplap, that I often employ. When nailed correctly so it can move, the wood will last for one hundred years, as is evident in many old barns still standing.
The best part of this siding style is that it typically employs local lumber. Most rural towns have a sawmill nearby. In our region, mills typically cut white pine and hemlock. I rely on a sawmill that has been in operation for fifty years:Collins lumber in Alpine NY. The mill was started by Bob Collins and continues to be operated by his nephew. The same saw has provided siding for hundreds of barns, sheds, and other outbuildings in the area. What is distinct about the operation is that they use a traditional circular saw. Many newer sawyers use a bandsaw mill, perhaps even a portable unit they can bring to you. What I like about the wood I have been getting from Collins for the past thirty years is its character. The circular saw marks on the rough-sawn boards create a pattern with repetition but also pleasing randomness—like jazz. Certain saw teeth will mark more than others. No two boards are alike. It’s unlike metal siding, cement board siding, or any manufactured material typically used in construction today. The boards speak of the trees, the mill, and the rural landscape.
The traits of these boards are the kind of thing you might never notice. Except when you come out of the sauna and have time while you cool off in the fading light of the day to stare at the inconsequential things in life that surround you—sunbeams raking across swirling marks left on a board by an old saw blade.
If the heart of the sauna is the kiuas, or sauna heater, then the soul is the rocks.
Every brand of sauna heater I’ve installed has a different approach to the rocks. Some, like a wall hanging six or eight kilowatt unit use less, maybe forty pounds. And some, like the Harvia Cilindro or Club heaters use more, up to two hundred pounds. Wood burners vary too. Kuuma’s heater takes one hundred fifty pounds or so, but you have to provide your own. My custom-built stoves (Lämpimämpi brand) take a similar amount of stones and like the Kuuma stove, the rocks are piled on top, mounded as high as you can. The Harvia Legend, an elegant wood burner from Finland, has a basic cage surrounding the stove. By the time you are finished loading the stones, you won’t see the stove. There is also an optional cage that surrounds the stove pipe that hold even more rocks.
The Finnish and Swedish heaters use olivine diabase or peridotite, igneous rocks found in Scandinavia. The rocks I have used that come with the electric heaters look the same: grayish chunks, some flatter, some chunky, all in the size range you’d find in a bag of potatoes. These are amazingly cheap, considering that they come all the way from some quarry in Finland or Sweden. The UPS driver stopped asking what was in the boxes (“yup, rocks”). Once, I found a note in one from a young Swede, hoping that I was happy with my rocks.
My favorite rocks are hand-selected glacial erratics: various igneous granitic and metamorphic stones that I find in places where glacial melt waters sluiced out potato-sized rocks.
These are heavier and denser than our native shale, which is worthless for the sauna since it tends to explode when heated. The erratics have a crystalline structure that you can usually see and a solidity and heft evident when you pick them and bang them together (they are not easy to chip).
My favorite rocks.Lämpimämpi with glacial erratic rocks.Lämpimämpi with jagged olivine diabase rocks.
A significant consideration when selecting a heater is the rock capacity. The more rocks, the longer you should let your sauna heat up. Clients always ask: “How long should we let it heat up?” While I usually say, “About forty-five minutes,” I really want to answer with the same sort of retort I give when someone asks how long it will take for paint to dry (“as long as it takes”). The correct answer should always be: the sauna is ready when the rocks are hot enough to produce good löyly or steam. Löyly is the soul of the sauna’s mysterious expression. And how hot is that? Four hundred fifty degrees Fahrenheit, more or less. If you want more steam, then you want more rocks.
Löyly is the soul of the sauna’s mysterious expression.
More rocks are good If you expect several rounds or people coming and going. No one wants to pour water on the rocks expecting a stimulating burst of steam (but not too sharp), only to hear the fizzle of water barely boiling. That’s like trying to make an omelet in a pan that is barely hot. Disappointing, to say the least, but also bad for the heater. There’s a Finnish saying that goes something like this: when you leave the sauna, put another log on for the sauna elf, or he will pee on your stove. Which means don’t keep throwing water on the stove, especially at the end, if the rocks are not hot. The warm water will just sit on the steel stove and rust it. When you throw water on the rocks, it should all turn to steam, and when you are done, the stove should dry quickly. When I finish eating my omelet, I rinse my cast iron skillet and let it dry over the flame; I don’t let it languish all wet in the dish rack. The same principle applies to the sauna stove.
Jagged rocks will catch and momentarily hold more water, allowing less to get past the rocks and into the heater. The dense, roundish rocks I use produce a nice soft steam, but they have to be hot. I’m not so worried about water getting down to my stove, which is always very hot. (Lämpimämpi stoves have 3/8” steel plate on top so they will never rust out.) By the way, always use clean water and be wary of city water with chlorine or even country water with minerals or methane. We use only use filtered water or rain water for löyly at home. Spring water or distilled water might be prudent in some cases. Never use pool water or, worse, let some disrespecting novice wring out their bathing suit over the rocks, as I have seen in a gym—pleasant smells should emanate from the rocks. Special sauna oils or even Sauna Brew can be added to the löyly water for aromatic effect. Heck, we used to add beer to the water (cheap lager was always best).
Custom sauna with Harvia Cilindro and carefully placed olivine rocks.
If your electric heater comes with the jagged, grey olivine rocks, I suggest using them. They are selected to fit between and around the elements. When setting the stones, first I rinse them, then I take care to arrange the rocks one by one. It can take me forty-five minutes to fill a large capacity heater. For the Cilindro, I place large rocks at the bottom to hold up the others and then work a flattish layer against the cage wall. I then backfill against the elements with smaller and irregular rocks. On the smaller, wall-mounted units, I try to fit the flat stones between the elements without forcing or bending them. The goal is to loosely fill the cage so there is good airflow and to completely conceal the elements. Lastly, I top off the heater with larger stones and try to arrange them so they will catch water and force it inward, not splashing it out. In Finland there might a “spirit stone” placed here: a special stone or stones from a favorite place (make sure it is igneous or metamorphic—test it in a campfire first if not sure). The top might even have a layer of more decorative stones, which in Finland you can buy from sauna dealers, but here in the US, I have only seen the same dull grey stones. The Harvia web page has a good section on stones and how to place them into the pillar.
Once you have the sauna going and have been using it for a year or so, expect the stones to settle and flake off. You should remove them, vacuum out the heater and replace the rocks loosely, discarding the broken ones and adding more if needed. Failure to do so will cause the heater to eventually overheat and lead to the elements failing.
Care in selecting and placing the rocks will ensure that your sauna…Rocks!
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