Giving thanks for the bread (oven) – with plans for building a wood fired clay oven of your very own.
As we get ready to fire up for Thanksgiving, I’m reminded how lucky I am. Not many cooks have a huge wood-burning outdoor oven, but thanks to my loving ( and very handy) husband we have two, one in New York and one in Maine.
Bill built the Maine oven so the process could be filmed, so in a way I can thank The Three Thousand Mile Garden for that one. But that one never would have happened if the New York one hadn’t came first, and although Bill did of course build it the ultimate thanks there should probably go to his childhood.
There were several outdoor bread ovens in the neighborhood where he grew up, including one at his grandmother’s place. He never forgot the bread – or the fact that the ovens were home built – so when I started making wistful noises about how nice it would be to have one they fell on receptive ears.
Next thing to be thankful for: he’s a man of action. And that goes not just for building the ovens but also for providing instructions. You too can have one of these things, not without a bit of work and not instantly, needless to say, but very very inexpensively and it ain’t rocket science, either. Here’s his step by step how-to:
THE OUTDOOR BREAD OVEN
story and pictures by Bill Bakaitis
For a number of years now, ever since The Three Thousand Mile Garden TV series aired, we have received a steady stream of requests for assistance/plans/advice for building an outdoor bread oven similar to the one constructed for that series. The latest request, from a school in Australia, prompted me to post this commentary.
I know it is not time for most of us in the Northern Hemisphere to begin construction, but we can dream on and plan for the spring, while the Australian crew begins work now. In the plans which follow the first four or five steps can actually be done now, in winter, well in advance of that burst of construction that comes with spring.
Our two ovens, the first in New York, and the second in Maine, were inspired by reading The Bread Ovens of Quebec*, by Lise Boily and Jean-Francois Blanchette. Although the Italian side of my family, and the community in which they were immersed, made and used several outdoor ovens, these were all made of stacked paving brick and mortar. That tradition quickly fell into eclipse as the American-born children of my mother’s generation found the glory of ready-made, plastic-wrapped, balloon-bread. Why not? It Builds Bodies Twelve Ways proclaimed the wrapper. It was quick and easy to buy, to eat, to forget. Sort of soft in the mouth and in the mind, an authentic American product of the 1950’s.
I was too young to fully understand how those Italian bread ovens were constructed and Uncle Richard, my mother’s brother could find only one person, Angelo Don Francisco, who recalled how it was done. His sketchy instructions, however, were no match for the weighty anthropological reconstruction of the French Canadian ovens described by Boily and Blanchette. It is a text I highly recommend. All of our plans and techniques were highly influenced by their research.
Here is how we did it.
HOW TO BUILD A CLAY/BRICK OUTDOOR OVEN
1. DIAGRAM YOUR OVEN:
Decide upon the size and shape of your oven. From the photographs on p. 69 of the Boily/Blanchette text, a simple scaling grid overlay set for the length you decide upon will give the height of the oven and its position at apex. The formula and graph on pp. 38 and 39 will give the height of the door opening relative to the height. From p. 48 the length to width ratio of the base can be determined, and by subtracting the 10″ thickness of the clay ‘loaves’ which will make the side walls of the oven the inner size of the oven will result.
Both of our ovens closely followed those dimensions used in the construction of the oven constructed for Boily text.
The base (see step 2 below) is 75″ X 47″ OD. The inner height of dome at apex is 32″, and the outer dimension (w 5″clay wall above) is 37″. The height of our door opening is 20″; the width of the door opening at its base is also 20″. This gives a theoretical working interior of 27″X55″ (24.5 sq ft) although the Maine oven turned out to be substantially larger than the first one we made in NY.
This size oven will bake @ 10 round loaves plus 4- 8 baguettes of bread, along with a small pizza or two in one baking, followed by a few pies and slow cooked beets, tomatoes or other vegetables using only the residual heat of the firing. It is the long heat storage time of the clay mass which makes all of this possible.
If this oven is too large for your needs, you will want to reduce the dimensions by following the ratios arrived at by the research team. Leslie will describe various baking processes and techniques in a separate post.
2a. DECIDE UPON THE LOCATION OF YOUR OVEN:
It should be close enough to the kitchen to be convenient for watching the fires, transporting the raised loaves into the oven and the baked loaves into the house, as well as loading the oven with all of the subsidiary items to be baked: pies, roasts, root crops and the pans of ripe tomatoes to be put up. At the same time, consider the fire hazards and avoid placing the oven next to a combustible structure. You will see that we realized the importance of safety AFTER we built the New York oven. Over two tons of stone, mortar, and clay are impossible to move, and we need to be especially mindful of fire hazards when we use this oven, which places limits on the times we can safely use it.
2b. BUILD A BASE OF STONE, MORTAR, SAND AND RUBBLE:
It should be as long and wide as your plans dictate and end up being knee to thigh high so as to make the heavy work of tending the fires and baking the bread easy. Ours was made of stone and matter that we gathered from our yard and garden. I swept the road before the road crew in the spring for much of the sand and gravel, and some stone I gathered from road cuts in the area.
3. POUR A CEMENT HEARTH:
3a. Lay a pair of full dimension 2×4’s (such as the rough cut stuff found at sawmills) on edge across the top of the base during the last round of leveling. These will extend out beyond the side of the base and will become the support for the roof. If you can only find lumberyard milled material, it may be wise to double up or go with 4×4’s.
3b. Over these construct a 2X4 frame around the perimeter of the base. This will correspond to your OD measurements. However, if you extend the 2X4’s a foot to the front of your base you will be able to use these arms as a foundation for a removable apron, useful for staging the loaves after the fire has died down and the coals have been raked.
Fill this void with cement, imbedding the metal door frame 2 ” into the cement. For good measure I placed a few bolts through the perimeter 2X4’s into the inner void, to be firmly affixed when the cement was poured. In this way they become permanent redundant construction members able to be used in the future if need be.
3c. Our metal door opening frames were bent at a local foundry from stock 6″ X 3/16″ flat AR metal. Remember to add a 4″ lip on both ends and to have the height 22″ (for a 20″ opening) since it will be set 2″ deep into the cement.
All of the above can be done this fall and winter preceding the spring work with the sapling armature and clay. Winter is also a good time to locate and test the clay for step 5.
4. BEND A FRAME OF SAPLINGS INTO THE SHAPE OF AN IGLOO CAGE:
4a. With magic marker trace out the inner dimensions of your oven; mark the apex point.
4b. Nail together some scrap lumber to hold the saplings,
4c. Gather together a few dozen flexible saplings .5 to 1.5″ in diameter. Apple, Maple, Viburnum, and Alder are all good. Gather more than you think you will need. Then begin the bending, shaping and wiring using the thickest saplings to set the major meridians. I used electric fence wire or twine as needed.
4d. As the shape comes into being you can progress to smaller and smaller twigs. To my eye this armature is the most beautiful part of the oven, and yet it is there to be sacrificed in the first fire. Photos alone will save this work.
4e. Cover the armature with old sheets. We learned that by doing this the resulting interior of the oven is both smoother and larger.
5. OBTAIN YOUR MARINE CLAY: Locate and test your clay. In NY we used some from the east bank of the Hudson River. In Maine a local farmer brought us a load. Before you even bring the clay to your site, however, you will want to test a small loaf by firing it in a bucket of burning sawdust. The first site I came upon made a great looking brick, but it crumbled at the first touch
6. MAKE YOUR CLAY LOAVES AND BUILD UP THE OVEN WALLS.
During this process it is VERY important to wear a pair of tough rubber gloves. Otherwise the clay, which has a high pH, will work its way under your fingernails and into your skin causing puckering, chapping, and painful lesions. Take it from me, and I ain’t tender.
6a. Mix marine clay with sand and earth into a doughy paste. Children tromping in a mixing trough are traditional, but a rototiller works better. As it is used it will chew up a small depression in the ground into which clay, sand, and water can be added to the rototilled earth making a superb mixture. The object is to lighten the clay and make it sticky.
6b. Bind the clay with hay or straw into “loaves/bricks” of about 20-40 pounds each. Clay is incredibly heavy, even after lightening it with sand and earth. The purpose of the straw is twofold: it binds and lightens the bricks, making them easier to work with, and more importantly creates a myriad of air passages that allow steam to escape during the firing process. Without these passages the bricks will explode. You can easily see why the early brick making industry was located near places where both salt hay and marine clay were available. Haverstraw Bay, for example, is derived from “Paver straw”.
6c. Set the wet loaves of clay over the frame, molding them together. The walls should be 10″ thick at the base gradually thinning to 5″ over the top of the oven. It helps to lay in a course of reinforcing chicken wire over the first few courses above the metal door opening as this area expands under use, the heat causing cracks. We did not know to do this on the NY oven and a permanent crack now exists over the arch. The second oven, in Maine, incorporated the chicken wire reinforcement and has only two hairline cracks to the left and right of the arch, a result of better distributing the stress of expansion.
6d. I placed a single removable plug into first course at the rear of the oven so that I could use this as an auxiliary air intake if needed. A threaded pipe with end cap could also be used.
6e. Allow the clay to dry for a month, loosely covered to protect from the weather until the roof is built. Patch any cracks as they appear.
7. ROOF YOUR OVEN TO PROTECT IT FROM THE WEATHER:
Once fired, the clay will become brick on the inside, but the outside will remain clay and must be protected from weathering. We originally used the board and batten method used in Quebec, but now (16 years later) are having the wood replaced by corrugated metal roofing, which is both fire proof and rot-resistant. For either method use the 2X4’s (3a above) as the platform. They run crosswise under the hearth. Lengthwise over these attach another set of 2×4’s and then use these as the base onto which the roof is supported. Since some rot appeared in this secondary set over the years, I used pressure treated material this year as a support for the metal roof.
8. BURN OUT THE ARMATURE, FIRE THE BRICK:
At the end of the drying period, a series of small fires inside will burn out the wooden cage and turn the clay into brick. These first fires will demonstrate the efficiency of the door to dome ratio planned in step 1. A bed of fire brick may be added above the cement floor. For us, they seem to work better than the naked cement.
9. MAKE A DOOR:
Now that all the wood is burned out the clean sweep of the metal door frame provides a perfect template for constructing your door. I used a plywood core with aluminum flashing on the inside, boards on the outside and wooden handles. It is only put in place after the fire dies down and the coals are spread out to temper the held heat, and also during the baking process itself, so it will never see direct flame.
10. TO BAKE:
10a. Build 2 fires, 1/2 hour apart. Build the first fire in front and then push it to the rear as wood for the second fire is added. If one large fire is laid, flames will be more likely to shoot out the front and ignite the A-Frame roof. To be safe, we keep a fully charged garden hose at the ready as we fire the oven. When the fire dies down spread the coals evenly over the entire surface of the hearth.
10b. Rake out the coals; we use a hoe to scrape them into a metal wheelbarrow or bucket. Use a wet mop to swab out the hearth.
10c. The bread is laid directly on the hearth, the door closed and the held heat of the brick does the baking: 10 minutes for pizza; 20 minutes for small loaves; 30-45 minutes for large loaves.
More on the baking techniques, some tested recipes, oven maintenance tricks, etc. in future posts.
The Boily/Blanchette text has a much more detailed description of the construction of the oven. You will want to read it for the more complete process, particularly if you are a guy like me who assumes the y chromosome is a natural problem solving device.
*Note: After Bill put in the link for buying the book, we learned it was a lot rarer – and a lot more expensive! – than we realized. If you don’t mind downloading lots of pdf files, you can get it free online from the Canadian Museum of Civilization.
Addendum: Using Salt in the Clay
We did not add any salt to the clay we used in either of our ovens. The NY clay (pictured in the back of the truck in step 5 above) was used almost as soon as it came out of the ground. It was blue-gray, sticky and eminently moldable.
We did not witness the digging up of the Maine clay so cannot comment on how long it had been out of the ground, but it arrived in a sticky moldable condition. Nearby ‘marine clay’ in situ looked just like the NY clay.
In neither case did we “weather the clay first” as Boily and Blanchette describe. Since they refer to the excavation of French Canadian clay from intertidal areas one can assume it was also ‘marine clay’. This may mean it contains some sea salt, but if so their ‘weathering’ of the clay would seem to allow the natural rains to wash away any unbound salt. Dunno!
Boily and Blanchette refer to the addition of salt “perhaps to harden [the clay] and make the mixture waterproof” (page 15) and indicate that this was more common to the Gaspé Peninsula. Checking various atlases I see that the Gaspé is primarily a rocky upland area where the Appalachian Mountains meet the Laurentians and where the glacial clay deposits are likely to differ from the lowland clays of the St. Lawrence River Valley and the broad Coastal Plain.
Elsewhere in the text (page 22) they say that sometimes the dome is protected with a layer of chalk or mortar. They appear not to mention the use of additional salt in the construction of the oven they documented.(page 47 following).
Although potters sometimes use salt to produce a glaze on their pottery, the heat of these bread ovens stays mostly inside the ovens. Ours have never produced enough heat to vitrify the outside surface, so whatever protective hardening the salt might produce, it probably wouldn’t be in the form of a glaze.*
If you want to try using salt it would be wise to test proportions in advance. Make two test bricks of approximately equal volume, mix a roughly measured amount of salt into one and leave the other au natural. Bake both in the sawdust bucket (step #5 above) to see if there is any difference.
*Salt-glazing involves throwing 10 to 15 pounds of salt or a salt/water mixture into the kiln during the final phase of firing. At temperatures of 1,100 degrees or more, hydrogen chloride is produced. When the hydrogen chloride bonds with steam or atmospheric water vapor, it becomes hydrochloric acid gas. The acid then interacts with the clay to produce a glaze. Truthfully, I would rather eat white bread than to breathe Hydrochloric acid vapor!
Photos of Bill building the oven by Leslie