By Heike Holthaus – Much has been written about the construction of masonry stoves. Plans, materials and the finished products are as versatile as the masonry stove itself. Though originally meant to bake bread, everything from granola to pork roast can be baked in them. Actually, to make the best use of the investment of the wood to heat the oven mass it seems a good idea to plan ahead and bake more than one loaf of bread. Take advantage of the fact that, once heated up, the oven will provide you with several hours of heat.
We found our masonry stove plans (you might also try researching Russian stove plans) and built our first oven in the summer of 1999. It was put through heavy use in the next two years and cracked considerably. In May 2000, we decided to try again, combining what we had learned the first time with ideas from several books on masonry stove plans.
Our Masonry Stove Plans (The Second Go-Around):
Keeping a 10-foot safety distance from the house and any other structure, we leveled a 60” x 80” area. Arranging 20 8” x 8” x 16” cement blocks we made a 40” x 64” base. We put a second layer on this one to gain height, but that could be eliminated (saves you about $20). If you plan to use the oven in the winter or want to be able to bake several loads of goodies in a row, you will want to insulate the oven floor. To do this you can either fill all the cement blocks with stones and cement or perlite. The perlite only insulates, while the stone cement mix is capable of storing the heat. All that was capped with 8” x 2” x 16” cement cap blocks. On this base 44 fire bricks were centered. As a frame to hold the form for the dome, we laid two rows of four fire bricks over the backside, and five bricks on either side, giving us a U-shape of 36” wide and 49.5” long.
For the form we used a 4 X 8 sheet of thin flexible paneling. We cut a 4′ x 4′ piece and drilled three small holes in two opposite sites. After bending it to a dome shape with the bottom part wide enough to sit on, the U-shaped fire bricks we secured in the shape with string and set it in place. The back wall we cut from the leftover paneling. For the chimney we cut a hole in the back panel, 6” from the top and 6” in diameter. Secure the panel with duct tape to the dome shape. For the first oven we used a wooden door. We found that to have two drawbacks:
1. You can regulate the fire only by the means of the bricks stacked up in the front to adjust the air intake.
2. Over the course of two years we had to make four new doors. The stored heat was high enough to scorch the door to the extent that it eventually wouldn’t seal right.
So the second time around we went to a local welder and had a door custom made. We spent $100, but it turned out to be worth it. (Doors from an old cast iron stove would work great, too, if you are interested in pursuing low cost construction techniques.) We agreed on an opening of 18.5” wide by 13” high, because the commercial baking sheets we wanted to use are 18” wide. (We bake our granola on them.)
And now to the fun part: Mudding! Using three parts adobe soil (clay rich soil) to one part Portland cement and water, we stirred the mix with hoe and shovel in a wheelbarrow to the consistency of thick oatmeal. The first layer of about 2” went right onto the form. Then a layer of 1/4” hardware cloth, more mud, chicken wire, more mud, 6” of construction wire and more mud. The total thickness ended up being 12”. In the back, we inserted a piece of 6” oven pipe. In between layers of mud we made sure that it had the right position and wasn’t pushed in. Since we were going to use our oven often and also wanted to be able to bake a lot of loaves in a row without having to reheat the oven, our shell is 12” thick. The first oven was only 5” and that was definitely not enough.
The total of 12” of mud was applied over the course of two days, covering the oven with a tarp at night, so it wouldn’t dry too much. After the last layer we let the mud set for a few hours and then went over the entire surface with a damp sponge to smooth it out. The oven was then left to dry slowly under plastic for a week. Before the first fire we let it cure for another week. Then it was time to put a final touch to the oven by installing the chimney. The cap serves as a spark arrester.
For the first two firings we built only small fires to further aid in drying the entire mass. And then the first bake day! We built a fire the night before and let it burn down slowly with the oven door opened only a few inches. That way the whole mass of the oven had time to slowly build up head and expand. The next morning we kept the fire going for about four hours and then let it burn down with the doors closed. That took another 1 hour and 30 minutes. By now the oven was heated up to about 700-800°F. We scraped out the coals and cleaned the oven floor with a damp mop. Our chimney is removable at the elbow, to plug the hole with a wet rag. That way we don’t lose any heat through the chimney. We tried dampers, but they burned out after the third firing. Over the next hour we let the oven cool down to 500°F. During that time the oven also evens out, otherwise you most likely would have hot spot places where you had a thicker log, for example.
We loaded the oven with the first batch of rye bread at 500°, and it baked for about 40 minutes. We baked three loaves subsequently, by the time we put the third loaf in, the oven temperature was around 400°. After the last loaf was done, the oven thermometer still showed 350°. Just the right temperature for the granola, or the croutons.
We use inexpensive oven thermometers to read the temperature. After replacing them about five times we learned to wait at least 30 minutes after the coals are out before we put them in the oven.
People who bake in these kinds of ovens are called “artisan bakers,” and rightly so. Stone oven baking truly is an art learned through trial and error, through success and failure. Through careful observation you’ll find out what works and what doesn’t. And of course, reading and learning from experienced stone oven builders and bakers.
For anyone who wants to know more about oven dynamics (how the oven stores and releases heat) and baking, The Bread Builders, by Daniel Wing and Allen Scott is an excellent book. (See the book review in July/August 2001 of Countryside – pg. 104). You might also want to look into masonry heater costs before you get started.
Some people like to get really creative and might want to turn their oven into a functional piece of art. They might want to took at Building Your Own Earth Oven, by Kiko Denzer.
I hope you find these masonry stove plans helpful and happy baking!
Published in 2002