Thank you ! I went through several videos about cob oven. I must say yours is one of the most educational. I learnt something. The sound is very good. I can understand everything although I am not a native english speaker.
great video, i can’t believe i havnt ran across it before, this woman does a very good job getting everyone involved and keeps it fun. good job to all👍👍
Good grief, I got all happy when they were eating the food. What an awsome project, I always want to see this done and now I know, thank you so much!!!!!
I see, thank you. I started my base today. My dome dimension will be 27" diameter and 19" high. Wow, it takes a whole lot more material than I thought! Thanks for the advice.
It certainly does! Thanks very much for your advice. We can't wait to get started and are especially looking forward to cooking our first sourdough loaves in our cob oven.
Thanks for the videos! I'm currently building a pretty big cob oven. It is going to be 4.5 to 5 feet inside diameter so we can bake about 20 loaves of bread at a time.
Hi Alan, the width can be anything that is functional to you and that still allows you to make a well-fitting door. It doesn't effect the functioning of the oven or the efficiency of the burn like the height of the door does. So make the width whatever size you want your pizzas to be. :-)
Wow! That's a really big oven! You will probably want to keep hot coals around the perimeter to keep the heat up, or create a 2-chamber oven with a fire below. You may also want to increase the thickness of the thermal mass to 6" or even 8". And you definitely want to increase your insulation to 8"-10" or more to keep your oven efficient. I'd love to see pics when you are done! :-)
For the layers...lots of people do thinner layers. These thicknesses are for optimal performance. If you make your first thermal mass layer thinner, your oven will heat up faster but it will also cool down faster. If you thin your insulating layer, your heat in the thermal mass dissipates more quickly to the outside (instead of keeping the heat inside). You can thicken the insulating layer on the top and keep it thinner on the sides, as 60% of heat loss is up. Hope this helps!
The brick is called "fire brick" and it's specific quality is that it can withstand the heat of the fire without cracking. Fire bricks also tend to have nice square corners, that make for a very nice, smooth floor. I usually buy from a masonry supplier, but you might be able to find them online as well.
Great question! Since we made the door after cutting the opening in the cob, it was difficult to create an exact fit. So I sculpted an arch inside the original opening using the door as the mold. This way we had an exact fit to the door and no heat loss through little gaps around the door. The material is the same mix as the thermal mass layer, so sand plus clay soil only (no straw). Thanks for the question! Hope this answers it.
Hi Pauline, I would leave the sand in place, as it will give you strength/support when you add the insulating layer. For straw alternatives, I have seen people using wood chips, but it's not quite as effective as the straw. One idea, however, is that you can build up a second thermal mass layer, just like the first one was, but leave a 3" gap between the two. As you build up, fill the gap with vermiculite or perlite (you can get from a garden supply place). That will give you insulation too.
Absolutely, that will work as well. You just need something for the form that you can either burn out or pull out easily as the clay dries. Brush would be in the "burn it" category.
Hi, and thanks for the great questions! For the door, the width can be anything, as this does not effect the air flow. The height is specific because that ensures that the heat transfer is maximized and that your exiting air will not snuff the incoming air.
gracias x acer estos videos gracias boy aser el mio tratare de aserlo ojala y m qde. saluditos desde tijuana bajacalifornia norte megusto ver la alegria de las personas ver terminado ese horno tan bonito ymas cuando los veo comiendo esa rica 🍕 felicidades
Great videos all of them , enough information to crack on and do one, which we have just about to get on with second layer, just not quite sure how dry the first layer needs to be...does any one know? Thank You for all the time and effort put in..:)
really you can use anything to make the dome form that you can also remove. With the sand dome, you dig out the sand. With a wood dome, you would likely burn it out. But both work just fine.
If your slice of pizza is not stiff enough, the dough is not cooked enough. Even with a thin crust, a pizza should always be stiff. The secret of good pizza, let the dough rest for a long time until it rises well (choose the right flour too: 50% durum wheat, 50% soft wheat) very hot oven, normally 400 to 450°c 750°f to 850°f for a quick cooking. It's extremely hot, the fire has to burn well (not just 3 embers in the bottom and 280°c (530°f) but that's it, then we take it out
So, I would either scale it down a hair...maybe do 48" interior diameter, which would leave you 15" to work with (maybe 6" thermal mass plus 9" insulation). Or yes, you can build the outside shape to be bulbous so you can widen the insulation as you go up. The top has the greatest heat loss, so for sure try to get a lot of insulation on the top. Also, there is a great new book by Tom & Satomi Lander showing a way to do an insulating cavity around the thermal mass (improving energy efficiency)
Best series of videos!!! This is by far the best tutorial ever, I'll give it a try. Thank you very much! I have few questions: 1.- Do you need to let the layers cure (dry) before adding the others? 2.- what is the composition you mentioned for waterproofing the oven?
You can add each layer one right after the other...however, the oven won't heat up to it's maximum temperature until all of the moisture has dried out of the clay. The best way to protect the oven is with a roof. The second best way is to put 2 to 3 coats of lime plaster over the oven (at least 1/2" thick total).
Hi There, I have built my first oven based on your videos- THANK YOU! I am wondering how long the structure needs to cure before I add a decorative mosaic tile layer to it. I would love any wisdom you might have:)
Thanks for the tips. Maybe I will have to scale it down a bit because the base is already built (6.5 feet wide) and I was planning on going 4.5 feet to give me 12 inches to work with on each side. Instead of scaling it down, do you think it would be ok to only have 12 inches on each side where it meets the base and then build the thickness of the walls as it curves away from the base to 18-20 inches thick??
Great videos! We have been inspired to start building a cob oven here in Greece. I have a couple of questions. Firstly, you give a ratio between the interior oven height and the opening, but what about the width of the opening? Is there a ratio we should use? Also, we have limited space where we will build our oven, so do the thermal mass and insulating layers have to be 4"and 6" respectively, or could we reduce these slightly? The interior diameter of the oven will be about 24".
Really great series of videos building this oven. Thank you so much. On this video around the door I notice the material is very smooth, almost like the surface of brick. Is this the dried internal thermal mass layer that is sand/clay without the straw?
I'm assuming it's just a matter of time, meaning letting the green dry out and be brown. The knapweed is pretty tough and dries to a toughness like straw. it's almost borderline twiggy when dried, because the stems can get to pencil thickness. would you recommend trying it, or stick with the tried and true? Worse case scenario is that it would not adhere well and crumble?
It is an amazing video. I need to ask some questions. Today I only need to know what is the name of the sand you used? I live in mexico, and a type of sand that is all around is the one we use to build concrete with. I don't know the name of the sand you used, but if you tell me the name maybe I can find it here too. Thank you so much for such a wonderful video.
Very impressive, informative videos. I am resurching to build a conventional brick oven and your the first one Ive seen that gives %'s on sizes. My big concern is air flow so this was very helpful. Thanks for the inspiration. Thank You
straw is not just dried out, it's biologically more similar to wood. What I would say is to do a test with the material you want to use before you commit to your whole oven insulation. Worst case scenario is that the knapweed biodegrades very quickly, leaving you with little or no insulation...in which case you would apply a new layer that does have good insulation. (In normal cob, the downside would be elimination of the tensile material in your wall, so worse outcome than for an oven)
Hi again. Delayed by weather but finally started our cob oven last week. The thermal mass layer is done, but can't find any straw for insulating layer. We live in rural Greece and things are only available according to the season! We have now found a farmer who can supply us, but not until the end of March. Would appreciate advice as to how to proceed. Should we cut out door now & leave sand in place - for strength when we add next layer - or remove it? Are there any good alternatives to straw?
Thank you for your answer! Now I have another question. There seem to be more than one kind of brick. How do I know if I have the right kind? Do they have a specific name? Can I buy them in Amazon? What happens if I use the "wrong" kind? I'm so confused with this issue. I hope you can help me.
Beautifull, do you know how much time does an oven like this can last if we think of cooking food 3 days per week and from 1pm to 11 pm? Is that realistic? I loove cob but i guess it would be easier to make a brick oven
would any natural plant fiber work to mix into the cob? If so, what characteristics would you look for (i.e. strength of fiber, fiber length, etc.)? I have fields and fields of invasive russian knapweed where I am and was thinking of using that instead of straw.
I usually use clay soil dug right from the ground where we are building the oven. I have a video here on my youtube channel that shows you how to test for clay content in your soil. If you have zero clay in your soil and no clayey soil nearby, then you can purchase bagged powdered potter's clay from a pottery supply place near you (some also offer online purchase & shipping).
Thanks so much for the kind feedback. I hope you are inspired to build yourself an oven! I'd love to see pics if you do build one. Also, I definitely recommend Kiko Denzer's book "How to Build Your Own Earth Oven" if you decide to build one. It has everything you need to know, including some inspiring photos. Enjoy!
thanks for the kind feedback! I am working on a DVD of natural building overview, to be followed by informational videos on each natural building topic. Stay tuned...! :-)
Hello, why did not you use wood? with it you can make the dome of the size you want, cover it with mud and straw, it would be to wait for it to dry but if there is a lot of dry wood you can set it on fire, if it is big it is better to wait, the fire will devour everything at end and to the cavo is an oven, the fire can sometimes be a great ally.
I know this is old as hell but hopefully I get a reply... what about putting a smaller almost fire box attached to the back with a small door and a small floo at the front door of the main oven... a rack inside May also help with heat transfer and this would also allow meats to be smoked as well.
Could you scale this up to biuld a shelter/ house using the whole "sandcastle" build method? How much larger can you make this structure without the roof collapsing? Thank you, cant wait to make my own.
DreamsCatcher101 As yet I'm still digging and sperating clay from the soil here (its like 10% clay). Got the garden looking really nice though and it's got me outside and enjoying the simpler pleasures in life.
Yes, but the quantities are different depending on the size you are building. That's why I asked about what size. If build the oven in the video, which is 36" INTERIOR diameter (where you bake), you will need about 300-500 lbs of sand, approximately 100 gallons of sifted clay soil with at least 50% clay content, and 3 to 4 dry, mold-free strawbales. Adjust quantities if your soil has different clay content. (If your oven is 24" inside, then divide quantities roughly in 1/2.)
Wow! Great videos. Too bad you guys are so far East (on the other side of the country), otherwise I'd consider taking an oven class. I was just outside testing the soil for clay content and found very little of it, about 20%, which may be all one can get here in the High Desert.
Was there any sand in the second (clay/straw) layer? Also, how long did you wait after the oven was built before you fired it up and baked the pizza? Was there any drying time? Thanks for the informative series!
So many questions! The straw looked like it might've been chopped up, what is it? The wood that appeared after you were inside the oven, What was the purpose and how did you do it? Would it be possible not to dig out the newspaper and just have it burn with the first firing of the oven? Where in West Virginia are you?
no chopped straw at all...there is long straw in the insulation layer. The wood supports were to hold up the dome because we got a little too excited and took too much sand out. I recommend taking out no more than 1/3 of the sand the first day, and then remove the rest over the course of a week. Yes you can let the newspaper burn. I'm in PA not WV...this was an oven I built for some clients in WV.
More questions noticed you recommended against using a machine for mixing. I'm 63, doing this by myself, and looking to reduce labor where I can. I have a very old mixer that we have used for all our concrete work... will the product I end up with be satisfactory? Also is it possible to use a form...say a cardboard barrel for a Canadian style rather than build a sand mound? Also, why no chimney? Thanks in advance... your videos really make me think I can do this!
Just found your channel. Subbed! One question. Is there a wait time in between steps? Like, do you need to wait a day after the thermal mass, before the cob? Thanks for the great video. I'm inspired
NJ Homestead You can usually dig out the front 25% right away (stop digging if you see any sagging). Then as the clay dries, the sand dries too...as the sand dries, it falls...so you can just keep scooping out whatever sand falls from it's dome shape. If you pull out the dry sand daily, the inner portion will dry more quickly. Usually the whole process takes 1 to 2 weeks max...depending on where you live, the temperature, how damp the weather is, and how big your oven is.
I've seen a lot of people use stucco as a finishing layer. any drawbacks to using that? Also, I see a lot of COB ovens that have chimneys.. Is there an advantage to having one vs not having one?
You can stucco as long as it is breathable, like a lime-based stucco. Not concrete, as that will actually cause erosion of the clay behind the cement and then the cement will eventually just pop off. For chimneys, if you size the door opening correctly, you don't need one. I prefer no chimney, since it usually results in heat loss during baking and also reduces your heat transfer of the fire/exhaust fully into the cob mass layer.
What type of sand did you guys use? I've read that beach sand or sand for sand boxes won't work. River sand? And how deep did you have to dig to get to the clay layer? We're in Ohio so our soil shouldn't be too different from yours. Thanks
My preference is concrete sand, which is angular in shape and has a variety of sizes (up to 1/4"). This makes the strongest cob. My second favorite is mason's sand (most often used for mortaring stone/brick walls). River sand is probably too rounded to be highly structural, since it is tumbled smooth by the motion of the river. Hope that helps!
