I’m excited about my latest project: a wood-burning mobile sauna.
Unlike all of my other projects, which I design and build to meet the needs of my customers, this one is for myself. Over the past five years, I have been without my own sauna. It’s a long story. Basically, I sold my house (and sauna) expecting to buy another and build a new sauna, but because the lending rules changed after the housing crisis, with a bias against self-employed folks, I have been stuck in renter’s hell. So, while my customers have been basking in the warmth of my creations, I have been languishing in a sauna-less purgatory, dependent on the generosity of my clients for the too infrequent sauna. Like the proverbial cobbler whose kids have no shoes, I have been the sauna builder without a sauna. For renters like myself, the mobile sauna is the perfect solution.
It is a 5’x8′ sauna built on a commercial utility trailer. It is lined with northern white cedar and fired by one of my custom Lämpimämpi wood stoves. It has an arched roof using laminated bent cedar supports and aluminum sheet. It feels a lot roomier inside than you would think and comfortably holds four people. And, yes, it meets the two-thousand pound gross vehicle weight restriction of the trailer, so it doesn’t require a huge truck to haul it.
I’ll use this sauna for promotion—look for it at various venues and festivals including the Ithaca Festival parade (Again! Our first mobile sauna appearance was back in 2014). I’ll be taking this one with me on vacation or to my favorite park or forest stop. So, if you see it, feel free to stop and ask me to show it to you. Who knows, if it is hot I might even have a few spare towels.
The stove, heater, or as the Finns call it, the kiuas is the heart of the sauna.
The role of the kiuas is to heat the room. But not like a wood stove, but by heating the sauna rocks, which in turn provide the heat and the löyly, or steam, that make a sauna what it is. In the savusauna, or smoke sauna, which arguably offers the most authentic experience, there is neither stove nor chimney. There is simply a pile of rocks made into a hearth. A fire is burned within (filling the room with smoke) until the rocks are hot. Once the fire is extinguished and the room cleared of smoke, the pile of rocks does its thing. Likewise, any sauna, whether it is wood fired or electric, is only ready when the rocks are hot.
When building a sauna, the choice of heater is important. But the rocks are even more important. A good heater will hold a hundred pounds, and thus, will make good löyly. A cheap heater will provide a few decorative stones, and you will feel like you are sitting in an electric oven. I have seen many well-designed saunas in my years and I have seen many poorly built saunas, as well. The worst use some variant of a cheap wood-burning stove with a dented pot of rubble or brick on top. In the best, the rocks are the focal point, and they get red-hot. Pick one up (with heat-resistant gloves, please) and drop it into a pot of water and you can make tea.
Left: Rocks shipped thousands of miles—only to explode in the sauna! Right: Cayuga Lake beach stones—can you spot the erratics?
The type of rock is critical: they should be igneous in origin, formed deep in the hot earth or in the furnace of a volcano. Think of these rocks as heat loving. Granite, grabbro, and basalt are typical examples. The Finnish and Swedish units might use grey peridotite. Then there is shape: smooth and round potato shaped rocks or jagged and broken pieces. I prefer the smoother rocks, but there is argument for using the jagged (more surface area). You can order a box of the latter from Tylö that will come all the way from Sweden. Once I opened a box to find a nice hand-written note from the fellow who packed them. Another heater company sent me a box from their supplier in Central America. Apparently, they needed a geology lesson. The polished siltstone rocks, once heated, started exploding! If you don’t want to have a box of rocks shipped half way around the world or risk getting impaled by rock shards, you can find your own.
Unfortunately, our local stone, meaning the rock that is cemented to the landscape here in Central New York, makes horrible sauna rocks. It is all sedimentary: shale, limestone and sandstone. Born in the bottom of ancient oceans, these rocks do not love fire and will complain by exploding if thrown into one. By the way, baptism by fire is a good way to test your rocks if geology eludes you—a good rock will happily glow red-hot. Thankfully, the glaciers that plowed through here brought with them piles of stone from places north that serve the sauna well. These are glacial erratics. As the glaciers retreated and melted, these stones were left behind. The resulting floods that carved our landscape left piles of these smoothed rocks (mixed in with plenty of local stone) in deltas, drumlins or moraines. I find them in the local gravel pit, which mines an ancient delta, or along the lake at my favorite park (another delta) when the water is low. Sometimes I take milk crates with me when I travel through the Adirondacks and fill them with potato-sized anorthosite rocks—which is what the moon is made of—and other pretty granites.
More important than the geology is the significance of the rocks. A Finn, even if they are using a heater with rocks packed in Sweden, will add a spirit stone or two: stones that come from home or some other special place. Stones all have distinct place markers and are borne of this earth and tied to a particular landscape. Except erratics. These have been swept from their homes in a geologic diaspora and found new homes as immigrants, oddities, and beautiful accents against the dull grey of the indigenous rocks. Even though I am made of local stone, coming from generations of Central New Yorkers, I have always related to the erratics: the outsiders, the immigrants, the atypical people. They bring us diversity, new culture and traditions like the sauna. In my next sauna, you will certainly find plenty of erractics.
Redhot Adirondack rocks / My Lämpimämpi stove / Stove wall faced with local field stone including shale.
Finishing a job is always a sweet endeavor. I usually budget in one day of fussiness: A day when I can pay attention to all of the little details, get the stove in place, and then, as a last step, give the sauna a test run. This is when I get to see how my efforts have paid off and take note of how the sauna actually fires. Is it hot enough? Is it light and airy and does it have that right sauna feng shui? Does it reach a good temperature and would Ozzie—the Finn who started me on my sauna-building path—approve?
The job I just finished is a modest affair: bare bones, applying that Finnish sort of pragmatism. I converted a kit-built garden shed, the type you’ll find lined-up on the edge of a big-box home store parking lot, into a simple sauna with no dressing room. I liked the challenge of working within a modest budget, and I liked the folks: down-to-earth, modern-day Helen and Scott Nearing types. I had to remind myself that a sauna does not have to be a luxury item, affordable only by those in the higher income brackets. A sauna should be as essential and ubiquitous as indoor plumbing.
I lined the inside with knotty pine—a low budget alternative to cedar. Sitting on the top bench, I noted that the smell of pine reminds me of my forays into woods here in the east. It is a familiar smell, close to my heart, unlike the rarefied smell of cedar. Aside from the knots, which will forever bleed sap that will inevitably find it’s way into someone’s hair, it is a fine wood to use. It is not as stable as cedar, but the inevitable cracks will open the sauna up and let it breathe. We always said that Ozzie’s old sauna at Podunk, with its gappy, knotty-pine walls and sagging ceiling, felt better than any other.
MyLämpimämpi stove fired fast and hot. The rocks quickly reached good löyly temperature and the first splash of water had me moaning in ecstasy. At no point did I feel that claustrophobic locker-room-sauna feeling of not being able to breathe. The dual windows filled the space with light. The benches will hold the couple, their kids and several neighbors. In term of essentials, it is a perfect sauna. Nothing more is needed—no fancy tile or trim work, no designer dressing room. It works, plain and simple, and it works well. It was the best sweat I’d had in a while, and a good sweat is almost payment enough.
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