We worked with Max Edleson on two projects at the home of a neighbor: a cabin stove and an outdoor cooking stove. The cabin stove is a compact masonry heater with a cooktop and an attached heated cob bench. This post will focus on the details of constructing the cabin stove.
For complete documentation, including course-by-course drawings and updates on this design, check out Firespeaking’s Cabin Stove Plan Set.
In 2011 the Sustainable Shelter class built a version of the cabin stove on campus in the Playhouse. We went over there to check it out.
For more details on how this stove was built click here.
This year we built an updated version of the Cabin Stove. You can read about the evolution of the stove design here.
The following photos are of the cabin stove we built:
Prep for the cabin stove construction included: strengthening the foundation in the area beneath the stove; creating a heat shield for the wall behind the stove; and running the chimney through the ceiling and roof.
Due to their weight, masonry stoves are usually laid on the ground – on a concrete pad, or earthen floor. In our case, we were dealing with a raised floor above a crawl space, built with joists. Prior to the class, the floor was prepared by reinforcing the joists with concrete supports. An additional pad of 3/4″ ply was also added above the floor to make a footprint for the stove.
We started off the first day by constructing the heat shield between the stove and the wall. Another group worked on prepping the ceiling and roof for the chimney exit.
The cabin stove dimensions are 40″ wide and 24″ deep. The chimney is 6″ internal diameter (ID) pipe. The pipes in the cob bench will also be 6″ ID.
The cabin stove has an internal firebox made of firebricks and an outer skin of red brick. Before building and mortaring the firebox in its place, we first constructed a mockup.
Max made a custom door for the stove.
The main door is for loading the firewood and can be left partially open as the primary air supply while the fire begins to burn. Once the fire is burning well, the smaller bottom door can be opened to the degree needed as a secondary air source. Both doors have adjustable closures to allow more or less air.
After making a few tweaks to the mockup (mainly in order to accommodate the screws for the door), we proceeded to build the stove. We laid a cinder block foundation, and then began laying the outer skin of red bricks and the inner firebox, layer by layer.
Note that the joints between the cinder blocks have received some mortar. The mortar mix for the cinder blocks was 2.5:1 of builder’s sand to local clay soil, with added water. Note: Builder’s sand has more aggregate (larger particles) than mason’s sand.
The mortar on the mortar board will be used for the red brick exterior of the stove. The mortar mix for the red bricks was 3:1 of mason sand to fine red clay, with added water.
For the firebricks, only a small amount of very liquid mortar was used — just dipping the edge of the bricks into it prior to laying them. The mix for the firebricks was just red clay slip with a small amount of fly ash.
Note the shims sticking out on the right side of the stove. They are holding the bricks over two openings where the cob bench pipes will be. After several courses of red brick are laid over the openings, the shims can be removed.
Note: Stove layer 4 also includes the two vertical soaps that demarcate the entry to the heat riser. The photo entitled Stove 4 is missing these two pieces.
The cob bench was being built simultaneously with the stove. Before laying the pipes in the bench, we laid a layer of cob onto the cinder blocks. The two pipes were composed of several pieces riveted together and taped with aluminum foil. At their ends they were joined by two “T” sections joined as an “H. The H joint was wrapped in galvanized flashing and then aluminum tape. The ends of the H form the clean-outs for the two pipes.
Note: Clean outs should be placed at the end of every horizontal run of pipe and at the bottom of every vertical run.
When the bypass is closed, heated air travels to the cob bench. When the bypass is opened, it bypasses the bench and goes directly to the chimney.
We cut the angled bricks on the brick saw.
Note: A non-combustible floor covering will be installed before the stove is used. The non-combustible hearth will extend 20″ in front of the firebox and 12″ either side of the firebox opening.
And finally…test-firing the stove!
For more info on this stove and detailed building plans, check out Firespeaking’s Cabin Stove Plans.