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.
Playhouse front door
The cabin stove in the Playhouse
For more details on how this stove was built click here.
Chris is holding a pipe that fits into the stove and can heat water when the stove is used.
Windows inside the Playhouse
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:
Cabin stove sketch
The cabin stove (cooktop removed)
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.
Empty metal box will provide 4″ air space between stove and wall. The front of the box is made of two layers of cement board lined with foil, with a sheet of ceramic wool between them.
Lining cement board with aluminum foil (shiny side towards the fire)
Attaching ceramic wool to cement board with dabs of silicone
Prepping the ceiling for 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.
Working on the chimney pipe on the roof. Note: 2″ minimum space all around the chimney.
Chimney information
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.
Layer 1, partial view
Layer 1
Layer 2 (partially complete. Still needs ash grate and the two bricks in front of the grate.)
Layer 2, with ash grate (still needs two bricks in front of ash grate. Also, the two bricks on the right, laying on their narrow sides, are part of layer 3)
Layer 3
Layer 4, almost complete. Just needs one more brick laid on its long narrow side, next to the right vertical soap. (Note the photo oriention has changed. The front of the firebox is now at the bottom of the picture. )
Layer 4, detail of inner left side. Layer 5 starting to come up.
Layer 5
Layer 5, detail inner right
Side view
Largest brick over batch box
Brick covering the left portion of the throat that leads to the combustion chamber
Max made a custom door for the stove.
Showing how door will be attached to the brick
Door attachment hardware, detail
Max drills a hole in the brick to sink the bolt, into which the screw will be threaded
Bolt placed in the brick
Showing how the door will be attached
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.
Starting to lay the cinder block foundation.
All-threads were placed into the ciderblocks holes, and tightened over a steel bar to hold the foundation together as one piece.
1st row of red brick laid in place.
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.
Max on the mortar board
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.
Tools for “striking” the mortar joints between the bricks.
Stove 1
Stove 2
Laying another two rows of red brick around Stove layer 2.
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.
Side view of shimmed bricks
Stove 3
Stove 4
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.
Pipes that will be inside the cob bench
Shims removed
Stove 5, layer mockup on the ground.
Stove 5
Large brick goes over the batch box
Inside the batch box
Another large brick covers the back left section
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.
Taping up the joints of the pipes that will be in the cob bench
Pipes cobbed over
Cobbing the bench continues
Clean-outs at the end of the bench.
Note: Clean outs should be placed at the end of every horizontal run of pipe and at the bottom of every vertical run.
Another row of red brick goes up
4 firebricks in a square create the top of the heat riser
Close-up of bypass valve
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.
Angled cuts on both sides prepare for placement of the jack arch.
We cut the angled bricks on the brick saw.
Using the brick saw
Cardboard sketch and cutouts of how the bricks will be cut to form the jack arch.
Cardboard cutout is placed on brick and traced and cut.
Jack arch bricks cut and labeled
Building the jack arch
Filling in with an clay/sand mixture
Attaching the door
Filling in the area between the firebox and red brick with a mixture of vermiculite and clay
Rope gaskets make a nice seal for the stovetop
Installing the stovetop frame
Here you can see how the shape of the filled-in material channels the hot air from the combustion chamber through a narrowing.
Detail of fill-in
Installing the steel stovetop which consists of one burner and a griddle area.
Installing the right portion of the stovetop which includes a hole for the chimney
Chimney attached
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!
First firing of the stove
For more info on this stove and detailed building plans, check out Firespeaking’s Cabin Stove Plans.
Nice job. Looks very nice, and I love the stove top.
one comment, it looks like you have your stove pipe installed upside down. Unless you have a dual walled pipe that is tapered and the top piece fits down into the lower piece, you run the risk of having any creosote build up run down outside your pipes, igniting and causing a fire.
all codes specify the pipes must be placed to act like a funnel to keep everything in the stove pipe.
Just keeping an eye out for safety.
thanks for your comment, brad. will need to check on that!
Very interested in DIY. Examining many plans, suggestions & sources. Appreciate all the advice I can get. Thanks.
As above.
Query. Is it functional to place the cob & pipes at right angle to the brick unit (ie, around a corner into another room? This is a real concern for my retrofit.
Hi Dave,
Have you checked out firespeaking.com? That’s Max’s website which showcases this cabin stove build and other projects. You might want to ask this question on their forum at: https://www.firespeaking.com/cabin-stove/
I think it could work to have the cob and pipes go around a corner, but check what other folks have to say. If you find out some good info, let me know. Enjoy the retrofit!