Earth Sky Time is a community-based organic farm in the beautiful,
wooded foothills of the Taconic mountains, just outside of
Manchester, Vermont, USA. In addition to year-round sustainable
agriculture, they also have a wood-fired bakery (featuring a massive Catalan wood-fired oven!) and make
other prepared foods like humus and veggie burgers.
During the autumn and
winter of 2012-2013, I was involved in the design and build of a
wood-fired rocket stove sauna at Earth Sky Time, for the enjoyment of
the EST community, family, neighbors, friends, visitors, etc. It was
an exciting and ambitious project, and we strove to make it highly
efficient, environmentally friendly, sustainably built, and locally
sourced.
The frost in Vermont
reaches deep underground, meaning more work needs to go into ensuring
a stable foundation is built. We chose to use simple, self-draining
gravel foundations under 6 cement pilings. A system of French drains
was also put in to ensure the whole site was well drained. This type
of foundation doesn't need to reach below the frost line, because it
allows water to drain out through the gravel. This way, any heaving
taking place as a result of the frost does not come into direct
contact with the cement pilings.
The building has a simple
timber frame, made of hemlock from Manchester's local Alligator Sawmill. The lower sills are half-lapped, and rebar stakes join
the pilings to the sills and posts. Then the sills were mortised out
a bit and the floor joists were dropped in. We used hemlock 2x6's for
the rafters, birdsmouthed over the top plate. They were spaced 1 foot
apart, to ensure we would have a strong base for the green roof.
We finished decking the
roof in time for our workshop on how to design and build a rocket
mass heater, which I co-taught with Tristan Reaper. We had a really
great group of participants, and it was interesting being able to
shape the building around the stove. It gave us the freedom to
incorporate new features into the stove that I hadn't done before,
like building a diagonal feed that passed through the wall of the
sauna. You can learn more about the workshop and the rocket mass
heater we built in my next post, Rocket Mass Heater
Design/Build Workshop: Earth Sky Time Farm.
The week following the
stove workshop, we went out and got all the EPDM rubber we would need
for our green roof from Brattleboro's ReNew,
a nonprofit promoting sustainable construction by selling second-hand
building supplies. We attached the rubber to the wooden decking with
Geogreen, a (supposedly) environmentally friendly roof bonding
sealant, and spliced together the long rolls of rubber with adhesive.
In the photos you can see the plant box component of the green roof
forming short walls along the edges of the roof. This will later
function as a giant plant box, holding the green roof in place on the
sloped roof while ensuring the building is dry underneath.
Next we waterproofed the
walls and sided them with pine, board-and-batten style. We insulated
the walls with rockwool, a fire-resistant mineral
insulation that offers a more environmentally friendly and non-toxic alternative to fiberglass.
We also installed our
low-e, argon-filled double pane windows and door. We came across some
contractors one day, throwing these into a dumpster. The windows were
brand new, still with the price tags on them and everything! Amazing,
the kinds of things you can find in a dumpster. We took the larger of
the windows and modified it to serve as the front door of the
building.
A partition wall divides
the sauna into 2 rooms: the changing room and the sauna room. In the
sauna room, we put up a special reflective vapor barrier to prevent
all the steam and moisture from the sauna getting into the walls. Its
heat reflective properties adds extra R-value to the walls,
too.
Over the reflective vapor
barrier in the sauna room, we installed cedar tongue and groove walls
and ceiling. In these photos you can also see the burly cedar frame
for the two-tier benches. The walls and ceiling in the anteroom were
done with pine shiplap.
The exterior was finished
off with some battening, trim, and some lime green paint for style
points.
And finally, we have the
photos of the finished sauna!
In some of these photos
you can see the small vent in the north face of the sauna, which can
be used to release excess heat and steam from the sauna. There is a
matching vent in the interior door to the sauna room. These two vents
can be used together to draw fresh, cool air into the sauna and cycle
out the hot, steamy air.
The secret closet in the
anteroom operates by pulling out a little peg to release the false
shelving, which swings upwards and rests on an opposing shelf. The
closet was sized to fit a mattress, in case any members of the
community wanted to take advantage of the super-insulated, cozy
building during the cold winter months.
We had held a sauna the
night before these photos were taken, during which the sauna room
maintained an easy 145 degrees Farenheit (62 Celsius), due to the
spectacular performance of the rocket mass heater. The exterior
temperature that night was around 15 degrees F (-10 C), and we left
the vents closed to protect the masonry from cooling down too
quickly. To our surprise, when we returned to the sauna the next
morning, it was still holding at 110 degrees F! (43 C). This is a
testament to the tightness of construction, the great insulation of
the building, and the high thermal mass of the masonry bench. The
bench absorbs the heat from the exhaust gases of the stove, and
radiates the heat back into the room, rather than letting it escape
up the chimney. You can learn more about the rocket mass heater used
in this sauna in my next post, Rocket Mass Heater Design/Build
Workshop: Earth Sky Time Farm.
Building the Rocket Stove
Sauna at Earth Sky Time
was a great experience, from start to finish. The welcoming,
community atmosphere of the farm really kept me inspired throughout
the building process. I hope it will serve to bring people together
and bring happiness to their community for many years to come.
- Ben
