After multiple requests for a build thread, I dug into my notes and put together this thread. This was built back in 2012. I first started by digging down to the sand and shale layer. I backfilled the area with crushed stone. I then poured a circular slab with rebar in it. Once cured, I set four half cinder blocks with a piece of rebar sticking up in the absolute middle of the slab. The blocks were mortared to the slab. I built a wood swing jig with drop ends. This was a guide to setting the stones in a cylinder. I started building up the Pa. fieldstone with mortar in a circle. Here is a better picture of the jig to set the outward edges of the stone. I let the mortar set overnight and backfilled with concrete and chunks of chipped off stone to fill the gap. I filled the half blocks with gravel and capped them with mortar for the next block layer. I only used a half pallet of stone for this project. This is the stone up to the second level of block. I did three levels of half block. The rebar in the middle was not mortared in so I could remove it when done. The stone was built up to 30" and the block layers were at 26". The stone was higher to allow for the insulating layer and sand bed to be built up to set the fire bricks. Here the stone is at the final layer. I have a bed of clay and perlite mixed for the insulating layer. I built up a ring of clay/perlite to contain the wetted sharp sand to set the fire bricks in. Here you can see the gray perlite/clay ring holding the sand in. The sand is being tamped and leveled to accept the bricks. Here are the firebricks set in place. This is where the food sits to be cooked. The white chalk line is where the clay walls are going to start. The rough cut edges will be buried under the walls. It took two attempts to set the bricks level. This picture is the wetted sharp sand that forms the dome and door opening. I put a piece of 3" PVC pipe into the middle and stacked bricks and stones to bulk up the form without needing to get more sand. I attached a DC fan with a small solar panel to help remove the moisture. I did use 150 lbs. of sand just for the form. Everything in this picture gets removed when the clay dome is set up. The sand is right up to the chalk line that was on the brick. The dome was covered in newspaper to let the clay release from the mold. Here is the first layer of clay/sand mix put over the sand dome. I had to pack it down to try to prevent cracking down the road. I made a tamper out of a 2 x 4 block to smooth the shape.
Continuation. Here is a picture of the first layer scratched and waiting for the cob layer. The wood for was cut to the proper ratio. I also cut a 5 degree pitch to the wood door rests against the opening and does not fall over. The black plastic edging is to make a smooth surface at the door and prevent the next layer of clay from sticking to it. The door is up on wedges that get pulled out when the dome is set and the door drops down to be pulled out. Here is the second layer. It is cob, which is sand, clay and straw. The straw makes air pockets, helping insulate the walls and retaining more heat. Here is the final sand and clay layer. I put so much time in the construction, I did not even think about the outside finish. I ended up putting beach stones in the clay around the opening. I had nothing thought out at the time. First fire. The newspaper is visible and will get burned out over the next few break in fires. Here is the roof over the oven being put on. These are white cedar shingles. I should have bought the "A" grade. These were not all square and rebutted. Lots of hand planning. I had the shingles stacked according to size to place them quicker. I really liked this part of the project. Here is the finished view. The walk leading up to and around the oven is my old concrete walkway laid in pack gravel. It was a nice, cheap, repurpose material. It takes a beating, and I can drop hot coals (and a pizza one time) on it without worry. Overhead wood rack. The heat dries out the wood nicely up here. The robins in the spring kept trying to build nests in the wood. The view from the neighbors yard. I had not finished the ridge cap as I was contemplating a cupola.
Really interesting. I am so glad you took pictures as you did it. Did you use refractory clay or ceramic clay? How many small fires did you have to do before it was cured? I actually thought the cooking floor was one piece in your earlier posts. mmmmmm - Campinspecter found 100 lbs of hi-temp refractory clay in the basement. I think he is going to make tunnels for the boiler out of it. Nah! we get too much wind up here on the hill to build something like this.
Awesome man, just awesome. What a cool addition to your yard and cooking repertoire, I love stuff like this. I think in your other posts you showed some small cracks that have formed. Are they not a big deal/did not crack all the way through?
Wow! Please make time in your schedule to come and build one at my house next summer. Thank you very much.
There are three layers, so the cracks on the inside probably don't go all the way through, just one layer of clay I hope. I am not too worried about them. I should get a few more years out of this.
Interesting. From your research before building, did you ever find an answer if the dome shape is critical or would an arched roof with flat back wall work too? I ask because I have a bunch of 13"x 13" x 3" 90% alumina bricks that would work awesome.
yes, dome shape determines some of the cooking characteristics. low flat dome is more of a pizza oven, Neapolitan. a higher dome is more of an oven. forna bravo is a good oven sight with formulas and such for figuring these things out. mine is a Neapolitan style pizza oven, the low dome reflects more heat down onto the toppings to cook them evenly faster.
Traditionalovens website has the brick dome construction build on there. I don't know what the door to dome height ratio is for brick ovens, but for mud ovens 63% of the dome height is a good rule. There is so much good information out there. http://www.traditionaloven.com/
