The latest sauna we built is an indoor electric affair. We installed it in a new addition that also holds a hot tub and pool, an enviable combination for a personal home spa. It has an ample window and large 10 kW Harvia Cilindro heater that should make the top bench a real hot spot. I love the view from that bench. Not just any view, but one that takes me back to my childhood.
The property is located on the eastern shoulder of Cayuga Lake, at a point where the land starts to dip dramatically downward to the long snaking shore. The slope is so steep here that you don’t see the lake, only the opposite side a little more than two miles away. Someone unfamiliar with our landscape might not be aware that the longest of the Finger Lakes fills a glacier-carved trough below. While the scene through the window feels close, it is in fact, a long journey away.
The most pronounced land formation is Rice Hill: the old skiing and sledding hill in Trumansburg [or Ulysses?] that at one time had a rope tow run off an old tractor motor. There’s a warming hut and two shallow ice rinks at the top of the hill where many a hockey game was played. When friends and I were too broke or didn’t have the ambition or means to go to the closest downhill ski area, we would go to Rice Hill and practice our S turns. I also recall many tobogganing adventures; it was the kind of hill where serious injuries marked a good run.
Just to the north is a ten-acre parcel my parents bought in the 1960s with the dream of building a house. My dad designed the home with all the meticulous detail he employed on his large-scale architectural projects. It was a three-story modernist affair with a flat roof and cantilevered balconies that would have commanded a view across the lake precisely to the location of this sauna.
In the early ‘70s, things turned south for my dad: there was a recession, he lost his job, increased his drinking, and the dream of the modernist masterpiece overlooking the lake deflated like a balloon the cat clawed. All we were left with was a model of the house my dad crafted out of mat board, with twigs as stand-ins for trees. Later, after I finished grad school and before my parents had to sell the property as part of a bankruptcy plan, I lived on the lot in a tent and tarp shelter, waiting for my dreams to come to life.
I bring all of this up because of the prevailing association of sauna with memory. So many of my clients, who are typically aging baby boomers like me, say they want a sauna because of the wonderful childhood memories they have of sauna time.
Perhaps their family has Finnish roots, and they experienced summers in Finland, or they had a camp somewhere with a sauna. Like my experiences at Podunk, these childhood memories start to loom larger with age. Memory acts as a filter; the important things are retained and the trivial is set aside.
Landscape acts as a placeholder for memory. Living later in life where I grew up, I constantly encounter places that stir memory. While working on this project, with my past literally visible beyond the window and across the lake, I was constantly reminded of my connection to this magical place in the heart of the Finger Lakes. Sauna is a keystone in all of this.
As with so many saunas I build, I stop work and dream for a moment; what if it was mine? But then, I hand over the sauna to the new owners so they can ponder their own dreams. In this case, the owner will gaze out the window at the immediate surroundings: Land that he grew up on.
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.
To save it the old Sauna at Podunk, it had to be taken down. The squirrels had invaded and filled the dressing room with a cache of black walnuts. 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 the woodstove, its door rusted open, was set in a permanent expression of whoa!
If the 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 about Podunk (Sauna Time, Sauna Ritual,Homecoming, Back to Podunk), this is the ninety year old sauna where many of us locals were initiated into the joys of sauna during the heyday of the 70s when the Podunk Ski Center was a mecca for Nordic Skiing and all things Finnish. The structure’s 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 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 eight.
What I did not know was how the materials related to its function: how it heated up so well, how it held a good Löyly and never felt stuffy, and why it never burned down. Aesthetics aside, these are essential components to a well functioning sauna. We often debated whether it had any insulation at all, so I was especially curious about that.
We gathered on a drizzly morning with a chill in the air. Ironically, it was 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 on the same site, the design as close to the original as possible. We proceeded quickly, each of us attacking a specific area. Beloved details, like the doors and little shelves in the dressing room, were labeled, wrapped, and safely stored. The repurposed barn siding was carefully removed plank by plank, 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 revealed 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 ’70s?) was a layer of Inselbric, the ubiquitous and horribly ugly asphalt siding that was used starting in the ’30’s until aluminum siding became popular. The product 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. This was over a layer of horizontal 1×6 pine boards, loosely spaced, which went around most of the building. The big surprise was under these boards: 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 had wondered about!
A web search of the logo style led to verification of the sauna’s 1935 date of construction. Vertical boards were interspersed with the cardboard with no apparent purpose. Was this to add thermal mass to the walls? The interior surface was initially all Beaverboard (an early fiber board) that had been 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’ve written about in a previous blog post. The skimcoated Beaverboard provided a vapor resistant barrier that held the Löyly steam for the right amount of time. Later, in the 1970s, this barrier was covered with 1×6, tongue-and-groove, knotty pine. Given the current popular obsession with cedar interior sauna walls, I wonder if a more authentic sauna might be simply plaster with wooden benches and back rests? The plaster and paint layers (probably lead paint) 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, the allowed vapor to easily escape and not collect as condensation. This is a very important consideration in any kind of construction. But one corner post had signs of severe rot. Did the plaster layer crack here and allow moisture to saturate the wood? That must have opened the door for a colony of carpenter ants that moved 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) simply hopped along the foundation slab behind the tractor, taking the chimney with it and sending everyone into fits 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 repeated the wall construction: plastered Beaverboard covered with pine. The tiny attic space was filled with a layer of cellulose—peppered with rodent droppings, and walnuts—empty boxes of rat poison, and a few old bottles here and there (which probably once contained hooch). One attractive bottle 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 the structure from burning down.
As for fire safety, it was barely existent. It was a miracle that the sauna didn’t burn down. There was charred wood throughout the attic, especially around the iron chimney supports.
Again, there were a lot of heavy boards laid across the ceiling joists, 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 cement chimney penetrated it. The stove below, welded by me in the 1990s, was so rusted it was deemed scrap.
The cement floor had sloped to a drain but was cracked and broken. The original cement pour seemed hodgepodge and lacked any rebar. Woodchucks had tunneled voids underneath it. The drain had allowed bathing—something the early Finnish farmers needed as the house probably lacked plumbing. The floor will be replaced with an edge-thickened slab as the foundation—with a solid gravel base over undisturbed earth reinforcement with steel.
I consider bathing an essential part of the sauna experience. It is a function of the sauna that informs my designs.
Perhaps one component why the sauna felt so good was all the brick work around the face of the stove—the stove was fired from the dressing room—a traditional design I frequently use. (External Feed Sauna >) This added about a thousand pounds of thermal mass to the hot room. Thermal mass holds heat and radiates it back into the room, very desirable. But it also means it will take longer to heat up. I typically use a lightweight fire wall (between hot room and dressing room) so the sauna will heat quickly and to lessen the load on the building structure. Perhaps I should rethink that and revert to the solid masonry I started building with in the ‘90s. Ironically, the brick work at Podunk was added in the ’70s. The old Finns in our region 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 original homemade rig. Fire safety will be based on science, not luck (or sauna Gods). The walls will be lined with cedar over foil (with an air gap!), 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.
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