Bread oven build in Haiti

[jmikeabbott]

Bread oven build in Haiti. We have a good source of block,brick, sand,and stone. No firebrick. and I have no idea yet on type of brick. this is a blind build. They use sugar syrup and ash for mortar. I don't expect to use this. I imagine there is Portland cement but haven't heard of hydrated lime. it will be a rather large long rectangular oven. It will be built at a church in the mountains. My thought for now as shipping is impossible is to use Block and brick for structure and figure out dome and floor material. Outside will be an old fashioned cobb for insulation. A roof structure will protect it from weather. I think building a fire inside is most efficient. Another build has the fire underneath and I believe this to be poor heat source..Suggestions are most appreciated. The pictures are of an oven many miles away. It appears to work but I question amount of wood it takes to get temperature. I have no info on how this was built.

[dakzaag]

I have seen a similar oven in Haiti, near the end of the south peninsula. (up in the mountains as well) I think you will be able to find hydrated lime without too much trouble. Remember that clay will work well also (preferably a yellowish clay as pure a possible) Solid brick should be available locally, just make sure they are clay based and not cement brick. Reclaimed brick might be your best bet. If there is a good vein of heavy yellow clay, you could easily make your own brick, or have them made with proper supervision. Many links to this type of building if you need them.
I was in Haiti two years ago and considered using local stone for the oven walls, but a lot of things could go wrong with that idea, so be careful. If you have a resource in Port, I believe you could find firebrick there, but the buyer would need to know exactly what to look for and be prepared to find a lot of other stuff besides firebrick.
Good luck with your build, Haiti burns way too much wood, deforestation is a huge problem so insulation is probably the biggest challenge, but also perhaps the easiest to overcome because of the many substitutions available to insulate.

[jmikeabbott]

Thanks for the input dakzaag. Where in Indiana are you? I'm in North central. If hydrated lime is not available we can use the local yellow clay we have onsite instead? As I mentioned this is a blind build for me. the guys going have never built a bread oven, but are local contractors. They have been waiting on another supply shipment for another project for over a year, so shipping.... I saw a guy on Utube https://youtu.be/eM5p9ZY7wUQ using cobb, clay and straw stomped and applied in as many layers as time allows. The straw creates air pockets as insulation. He claims if he gets oven to 500 degrees and does temp check every day after on average it looses 100 degrees per day with just cobb.

[dakzaag]

I'm north of Lafayette about 30 miles. I fully understand the logistics of Haiti...the masons in Haiti are capable but they rely on portland which will be fine for the base and surround, but not going to work in the oven part. Everything in Haiti is crudely built, effective but crude. You can buy block, or have it made on site. Poor quality, but they grout everything and use rebar so it holds up for the most part. If you use glass bottles, the air inside the bottles makes for an insulation. Problem is the glass makes even better thermal bridging so you need multiple layers. Better than nothing.
Perlite, zonolite vermiculite or similar insulation is probably available, but again the buyer needs to know what they are looking at so you don't waste time and money chasing it down.
The cob oven you mention is a possibility, but longevity is an issue because the vitrified walls are not durable to wood banging against it and tools used for cooking. I would try to get a brick/stone dome or coffin style burn chamber and floor and use the cob on the outside as your insulator. Massive amounts of cob, 12 inches or more. You can find a couple of decent cob builds on you tube. Tom T. has a three day seminar building one which is pretty well documented. You can also find a guy named max who demonstrates making clay brick and using them for building a stove/oven.
Labor is cheap down there, and they can get creative with an angle grinder and diamond blade to make a very carefully cut oven if you find decent solid brick. If you can get very tight joints then the dome can be assembled with Portland slurry and when it burns out, it will hold together just fine from friction. The cob on the outside will help hold everything in place as the Portland burns out if you keep the joints really tight.
Yes, the more pure the clay the better, and the more yellow (in my opinion) the more refractory characteristics it has. A blend of clay, lime, sand and a dash of portland will work pretty well to bind up the structure. The oven I saw was constructed of Portland and stone and the portland joints in the floor were completely gone leaving a cobblestone like floor. Still made good bread but a lot of ash in the floor. I have a few pics...

[dakzaag]

[jmikeabbott]

Fantastic Pictures! The mountains are beautiful. I was thinking of brick dome and brick floor. If we make mortar from A blend of clay, lime, sand and a dash of portland will it burn out like Portland mortar? tight fit is a must in my opinion but we are limited to the capabilities of the people at hand. Have you built in Haiti? You sound very versed on this subject! You aren't in Winamac by any chance are you? Im South of Rochester.

[jmikeabbott]

I guess my mind mileage is a little off! More like Monticello or Monon!

[dakzaag]

Monon area! I was in Haiti two years ago and would have built an oven for our hosts if I had another day to spend there. The portland will burn out, but since it is only a small portion of the mix, it mainly functions as a setting agent to help with the build process. The little bit that burns out is not significant esp. with tight joints. You will want to make sure the sand is very fine, take some fine screen material along to sift the course sand down to just the fine pieces. You don't need a lot, maybe a couple of buckets will be plenty for your refractory mortar. I could not tell if the one pic you posted is clay or what?
Brick composition is counter-intuitive, you actually want a softer brick than modern hard fired brick. Not too soft like the old soft orange, but I would try to stay away from a really hard dark brick if possible.
In Haiti you often have a choice of one, I understand. Lime, clay and sand all hold up to wood fire temperatures quite well. Portland looses its strength above 600 F. The cob can make a fine insulation but it takes a lot.
The baker I visited was building a house next to the oven, he had a concrete floor and pillars up and the block guy was making block when we stopped in. All on the edge of the mountain. It was quite surreal and hopeful at the same time, I could almost hear the Baker saying..."They have to eat bread"
Have you built an oven yourself? There are a few things to follow no matter what design you use.

[jmikeabbott]

The picture is yellow clay. I also sent you a private message. I have not built an oven yet and Im not invited on this trip. YET lol

[dakzaag]

Well you need to get on the team so this build goes well. A high mass oven would be very good for Haiti because of a number of reasons. They often cook for large groups, and are used to cooking with wood fires. (not always, but the traditional three stone fire is very common there.) By using a high mass oven, they can extend the life of the fire by several days which will conserve wood and encourage a variety of baking efforts. They are very social, and I have often thought that this type of oven is especially suited for the culture. It is important that the basics of a wood fired oven are followed. It would be perfectly typical for such an oven to be constructed with the vent inside the burn chamber. Both your picture and my example vent directly from the burn chamber and do not have the reduction (inner) arch necessary to achieve high internal temperature and absorb the maximum heat from each fire. The reduction arch also encourages secondary combustion which is important for efficiency and reducing pollution. A well designed oven made with locally sourced materials could be an example or pattern to be copied over and over again across the island. If you have any influence on the completion of this build, please try to stress how important it is to follow traditional design so that the unit can be as efficient as possible.