The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Anyone have an earth oven?

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Nancy's picture
Nancy

Anyone have an earth oven?

Last fall my husband and I started reading up on how to construct an earth oven, and we're pretty set on trying this. We have a good spot for it, and I'm looking forward to the challenge of baking bread in it. I've bookmarked a number of good web sites with pictures of builds, and I've read Kiko Denzer's book on earth ovens. We had planned to sign up for a weekend class that Yestermorrow offered last summer on cob building, but it didn't work out and it doesn't seem to be on this year's calendar.

Anyone with any hands-on experience building an earth oven have recommendations?

Nancy

Help Kneaded's picture
Help Kneaded

Hi Nancy,

While I don't have any hands on experience building an earth oven, I did seriously consider it for a while last year. The thing that has since deterred me is that I've read earth ovens aren't very fuel efficient - they require a lot of wood to get them up to temp. Since we heat solely with wood, I decided I'd better not waste it playing around with "mud" ovens. :) I'd be very interested to know how you make out with yours, though, if you'd care to post back your experience because I'd love to build one for use in the summer if it didn't use too much firewood.

Mike from WI's picture
Mike from WI

one consideration is clay type oven like the Big Green Egg. they run on very small amounts of fuel, very efficient and are able to hold consistent temps for hours.

Nancy's picture
Nancy

Maybe what we need is a support group for people who THINK they want to build one. The question is, would the support group help us to do it, or to resist doing it . . . ?

Biggles's picture
Biggles

I recently built a clay oven - it took a few weeks, mainly as I built it at ground level and got a sore back from bending all the time! I built the walls in a square, leaving a space at the front for a door. I then needed a concave frame to support the clay on the roof. I hit upon the idea of using thick tree vines, simply arched inside the clay walls, enough of them forming a criss-crossed concave trellis. I tied them with hemp twine and it was very strong. then I simply slapped wads of clay all over the framework and it has worked a treat. The vines have mostly burnt away now, but the roof is solid.


I imagine you could use split bamboo as well as vines. I used 70/30 split of clay and sand cement - still cracks a bit, but by spraying with water every few hours, this was minimised.


 

parbo's picture
parbo

Hello Nancy,

This is great idea. Taste of any cook in wood fired brick oven is very different.

I'm a member of one great group Brick-Oven Yahoo groups. Home page is Brick Oven

You can also find a famous book written by Alan Scott. He's web site is Ovencrafters, The Wood-Fired Brick Oven Builders

Another nice web site is also The Masonry Heater Association of North America. They have a lot of workshop and detailed information's too.

I'm from Turkey and live in Paramaribo, Suriname /South America and planning build a professional brick oven too. I hope it can be start if I can find a good place then we can share experience together.

Nancy's picture
Nancy

Thanks, Parbo! I've just subscribed to the Brick Oven Yahoo group and bookmarked the other links you recommended.

I hope to hear more about your brick oven plans.

Nancy

martin's picture
martin

Hi, Nancy,

I have got as far as getting a piece of land next to our house. I was intending to build a brick oven, but it seems quite complex to me. I am now considering trying to build a mud oven as a first step, we have lots of wood around here so fuel is not a problem.

Have you found any good designs, plans for a mud oven?
Regards,

Martin
www.bakerette-cafe.com

longlivegoku's picture
longlivegoku

I'm planning to start construction of a brick oven in May/June. I think it will take me most of the summer to get it finished, but man am I looking forward to baking in this thing. Along with reading Alan Scotts book, I've also visited many sites on this subject. I don't know if they would help in the building of an earth oven, but someone there may know more than me about it.
TraditionalOven is a great site hosted by a great guy. Rado has a wealth of information and is willing to send it out free, you just pay for the shipping of the building CDs from Australia. They include 350+ pictures in process though.

qahtan's picture
qahtan

you may get a few pointers from here...qahtan
http://groups.yahoo.com/group/brick-oven/

qahtan's picture
qahtan

And there is a couple guys in here that have built brick ovens, qahtan

thebreadbakersgroup-subscribe@yahoogroups.com

Eric's picture
Eric

I purchased Kiko Denzer's book and plan to build a mud oven this summer. Some friends of mine built one a couple of years ago and the results are impressive. Plus it just seems like a fun project.

Some advise from my friends (who also used Kiko's book) is to be sure to follow the instructions for the correct dimensions. Specifically, make sure the opening is sized properly. Apparently their dimensions are off and consequently it doesn't draft as well as it should, making it more difficult to build a nice fire in preparation for baking.

cahillmorse's picture
cahillmorse

We have built 2 earth ovens with our daughters, 5 and 8 - they are easy to build and work great. There is a great article in Mother earth news on how to build one (by the author kiko denze(?) ) which gives you the dimension info you need etc. You absolutelt do NOT need to pay for a workshop how to do this, it is easy and fun to do with kids. As far as using alot of wood - well  we gather a lot of sticks from the woods and maybe a few pieces of firewood chopped into smaller pieces it's not too much especially when you consider that you could do several bakings from one firing if you were well organized and prepared. The only difficulty that we have found with baking in the earth oven is knowing when it is hot enough or too hot. We have had several successful bakings and one where the bread got a little burnt on the top. One baking we baked bread, then some calzones and finally a pie all in one firing. We got all our building materials for the oven from around our land - the clay from an embankment along the brook as well as the sand and the rocks which we used to build an pedestal. Our first oven we left out in the winter elements and it collapsed so our second oven we made a roof to keep it covered. The bread we have made tastes so good, I don't know which is the reason why - is it because it is just great bread or is it because we lugged mud from the mountainside down to our site and got our hands all mucky and formed this big lump into something usable ---- probably both-- at any rate it was well worth the effort and a fun project to do. Now when we have campfires we fire up the earth oven too and eat fresh bread dipped in garlic and olive oil YUM  we have found that 2 hours is about the right amount of time to maintain the fire before we sweep out the ashes etc and bake the bread. I hope I have sparked a few of you to go build one of these --you CAN do it AND you will have fun!

breadnerd's picture
breadnerd

We built ours this year:

Lots of good sites of other builders out there-we followed the Denzer design as well.

pumpkinpapa's picture
pumpkinpapa

I've fired my oven several times but as it has rained nearly every day since we built it this past summer and with no roof there has been no opportunity. When one does arise something else on the farm comes up :( Oh well.

I tried an oak roof made from twelve 10 foot long white oak boards, bad idea as the oak began to bend almost immediately. So we have lots of old tin roofing which I'll use instead, just have to remove all the rust and paint it and we will be good to go.

Probably by this coming Wednesday I'll bake.

We have a lot of oak on the property and since one firing lasts for about 8 hours on under 20 pounds of oak the fuel costs are very low.

What did you use for your base? I see round stone, I used free cinder block and filled it with free gravel and it is as ugly as sin :) Next time it's all field stone.

I see your door at the side, what did you use to make it? 

breadnerd's picture
breadnerd

We used kind of ugly landscaping stones for the foundation, filled with gravel (and a layer of lava rock). We had them laying around from an old yard project, so it was a good use for them, not as cool as stone but cheaper for sure... We're thinking about doing a mosaic on top of them to make it look cooler--if we used pebbles and did a lime plaster we'd have a little greek-looking oven, ha ha.

 

The door is made from leftover pine--they're glued 3x3s shaped with a sawzall, ha ha! I need to switch the handle from 2 knobs to one handle, as I can't hold it in one hand which is a pain!

We made a metal roof over ours--it's been raining here too and BF said "well we have a roof now" and I commented that tending a fire in 45 degrees (F) and rain is not the most pleasant idea, even if the oven itself is nice and dry :)

 

Do you fire it for 8 hours or is that how long it stays hot? After a few tries I now let the fire go until the exterior of the oven is nice and warm to the touch, then I let the coals burn down. It will "bury" the thermometer needle at first (500+ degrees) and then gradually cool off, depending on how much I open the door. If I fire first thing in the morning, bake around mid-day, it's often still 250 degrees the next morning!

 

 

 

 

mountaindog's picture
mountaindog

I should probably wait until I finish the Denzer book before I ask any dumb questions, but I assume you only use the wooden door to conserve heat after the firing up is complete and you've raked all of the coals and ash completely out of the oven? So then there would be no fire hazard in using a wooden door? Good point about handle vs. knobs, I'll remember that..my husband is now getting very interested in the mud oven concept and is already planning where to place it!

 

We have a lot of bluestone on our property that I've made many walls with before, so I plan to use that for the foundation - but not looking forward to lugging it across the property to where the oven will be built. I was also wondering if there were a way I could use a piece of flat bluestone for the oven door if I could scribe its outline in the cob before cutting the opening, but don't know how I'd attach a handle to it, and maybe it would be too heavy. We too have quite a lot of leftover metal roofing from our house and barn roofs that we'll put to good use for the oven area.

 

One more question - my husband wants to make pizza in it as well, how large is the opening of your door as I know you make pizza too? The 13 in. opening described in the book's basic oven seems a bit narrow to fit a pizza or a roasting pan in for a turkey.

 

Pumpkinpapa, thanks for sharing your blog oven pics too, very instructive, and looks like your family had a lot of fun making that!

pumpkinpapa's picture
pumpkinpapa

You are quite welcome Mountaindog, I'm always ready to share!

For pizza I can get a 12 inch pan in fine, and with my cooking area I could do a lot of pizzas in there. 

breadnerd's picture
breadnerd

Yes, the door goes on after the fire and coals are taken out. I have a towel I soak in water, and wrap around the door for baking. This in theory adds some steam to the oven, and protects the door, especially in the "soaking" stage before baking. In this stage you close up the oven--after the fire is out--and let the heat even out and soak into the floor and walls. It's way over 500 degrees at this point, and my towel has big burn marks on it, but the door seems okay!

 

I think you can make your door fairly wide--it's the height that's important. I made mine just wide enough to fit a regular sized cookie pan through. I can fit 2 cookie sheets side-by side inside the oven easily--though it takes a little manouvering to get them in there (you sort of have to rotate them to get them out). I had an old wooden peel that we cut down to fit nicely through the door. It's about 9 inches wide, which is narrower than the door and gives me some maneuverability when I'm loading loaves. But, that means I tend to make pizzas that are 9 inches in diameter, ha ha! You can fit a lot of them in at a time though!

 

The main issue with the narrower doorway is that you tend to bang it up when loading and unloading, especially when the oven is really hot--and you're trying to get things in quickly and hold the door (I'm definitely still getting used to the process, maybe at some point it will be less chaotic, lol). Mine's getting a little chipped up--but I think we can patch it as necessary. I can see how a brick doorway might be nice eventually...

 

mountaindog's picture
mountaindog

I'm getting deeper into the Denzer book and just finished the chapter on alternative oven and door designs, about metal or brick doorframes and chimney placement. The arched brick doorway looks like it may be a good idea, and not too hard to make, to avoid the chipping with use. I think I may try the rear chimney idea too.

soapy's picture
soapy

You can also line the inside face of the wooden door with a piece of tin. The heat will reflect back in to the oven and keep your door from charing. Soapy

breadnerd's picture
breadnerd

Good idea, I think we thought of that already but it's still on the "to do" list along with the improved handle. I do like the steam from the towel though, so might do both methods.

We approached most of this project with the idea of trying it the simplist way and make improvements after we've used it a bit. Now with some experience I have a better idea of what I need--including some handy hooks around the roof to hang tools, and definitely a portable table that can attach to the structure.

 

I love your thermostat idea! I wonder if I can retrofit one. After 4 or 5 firings, I am starting to get the hang of determining temps. I go by the exterior temperature--when the outside of the oven is just getting warm, I let the coals burn down and then shovel them out. It's usually over 600 degrees when I'm done, and then I let it cool down a bit.

soapy's picture
soapy

I have had a cob oven for 4 years. I had planned on making one for about 10 years and finally found some strong young people to build it. They now live in England and have published a book, "Building with Cob" by Adam Weismann & Katy Bryce..available at Amazon....There is a chapter on ovens but the book covers all aspects of cob construction. My oven sits on a footing that is 5 feet deep to provide protection against frost heave. The footing is made of urbanite...broken pieces of pavement...locked together with bag mixes of cement. There is a shake shingle roof to keep the rain off the cob.

Most of the time I use the oven for pizza. There is a 10" thermometer probe drilled into the cob wall within 1" of the fire chamber and when I get the thermometer to read 550 degrees then I rake out the coals and get busy with pizzas. Make sure your oven opening is wide enough to clear your pizza peel with at least an inch to spare on each side. Make sure the height of the door opening is exactly 1/3 the height of the internal oven chamber and you will be able to build excellent drafting fires. My pizzas take about 5 minutes to bake and I can do around 12 without too much loss of performance. If I am going to bake more that 12 I generally have 2 small metal baskets filled with cowboy charcoal...not briquets...that I place inside the oven to maintain high heat.

Happy baking,

Soapy

mountaindog's picture
mountaindog

I like your idea of the thermometer probe.

I just finished the Denzer book last night so now I think simpler is better and will probably forgo the chimney idea as it may cause the fire to burn too fast and lose some heat...beside, the beauty of this design is it's simplicity. Thanks for all the advice everyone...it's 65 F and sunny outside today in upstate NY at 1000 ft. elevation, you could call it a January thaw except there is nothing to thaw! The ground has not yet frozen...unheard of here where the nightime Jan. temps are usually -10F to -20F, but a good day for outdoor projects so perhaps we'll get started on finding the right location and setting up the footers.

megamont's picture
megamont

 Hi folks,

I built my Adobe Oven several years ago and it is functioning beautifully.

I used a different recipe than the normal Adobe mixture and found it to be waterproof and had no problems with break down due to long and high heat firings. (compressed air assisted).

The Recipe;

(1) 2 Units of Calcined Gypsum. (C G)

(2) 2 Units of Portland Cement.

(3) 4 Units of Clay / Sand Mix.

(1a) C G = Plaster of Paris; To make your own; Your Nursery or Hardware store will have Gypsum in bag form, the stuff used to break up clayey soils. To make a test sample take an old large frying pan 3/4 fill it with Gypsum straight out of the bag and heat over stove ( gas or electric ) till the color has turned to white by driving out the moisture and gas bubbles have ceased to break the surface. At this stage notice how the Gypsum has taken on a state that can only be called "liquified powder". If you bought "coarse" Gypsum, after calcining it place it in a concrete mixer with 10 pieces of broken house brick, cover the mouth of the mixer with plastic secured with string to stop the fine dust escaping. Engage the mixer for at least 2 hrs ( the longer the better ) this will pulverise the C G to a fine powder. ( the finer the better and stronger )                                           

 For larger amounts I place a SS sink over an open fire and "cook" the  Gypsum.

(2a) Portland Cement; Straight out of the bag.

(3a) Clay / Sand Mix; = 15% Clay / 85% medium to fine clean Sand rundown.

                                  

Clay must be CLEAN; e.g. free of dirt or fossils.

I also pulverised the Clay/Sand mix in the mixer and run it through a 3/16 sieve.

Procedure;

 Assuming you have a Plug or shape formed up (internal oven shape).

Mix the above recipe "DRY" and 3/4 fill a wheelbarrow. At the shallow end of the barrow add about 1 gallon of clean water and mix in enough dry mixture to form a "stiff" workable compound. Trial and error will tell you when you have the right consistency.

 Do not mix up to much as the C G will go off before you can use it. The other advantages of this method are you can stop and start operations when ever you like and it's clean to work with (no MUD).

Apply 1 hand full at a time with firm pressure and tab or batter into position making sure an over lap occurs with each hand full this helps the bonding. When restarting on old work lightly mist the previous work to help adhaesion. Remember too much "WATER" will cause shrink cracks in new work.      

To fix shrinkage cracks simply fill the cracks with C G/Clay powder, (50/50) and lightly mist with water several times this allows the deeper cracks to be penetrated with moisture.

Theoretically this mixture will not shrink as normal Clay or Portland Cement dose when water is added for one basic reason, Calcined Gypsum "EXPANDS" when setting thus equaling out the shrinkage in the Clay and Portland Cement.

There is no need for a roof however a coat of Bondcrete and a 1inch layer of Stucco over the finished oven will guarantee protection from the elements.

With this method you will see it as fun not "work".

Happy cooking,

Regards,

Megamont

pumpkinpapa's picture
pumpkinpapa

Interesting application of materials, but clay free of dirt/fossils? My soil is 85-90% clay with the lighter stuff in the top soil. Sieving the stuff is back breaking work, and takes a lot of the fun out of the experience. What part of the world are you in? Can you work with this stuff in cold weather?

I found working with cob in bare feet a tremendously fun experience and I can't wait to do it again for other projects. It was relaxing and therapeutic, plus stomping in the mud is a good way to pass the time with loved one's. Doing it by myself was like kneading dough, it gave me a chance to let my mind wander and work out other things at the time. For larger loads I will just ask some friends if they wouldn't mind joining in, here's some good photo's of examples

I would enjoy seeing pictures of your oven if you can. 

 

megamont's picture
megamont

 Hi pumpkinpapa,

I live on a Volcanic Island off the coast of Queensland Australia about 30 miles from Brisbane the capital of Queensland.

My top soil is black and 12 inches in depth, from there it becomes semi clayey dirt and lite tan in color (12 inches) under that I was very lucky to have a 15% clay and a medium to fine run down of sand coupled up with ironstone rocks about the seize of cricket balls.

I had a backhoe excavate a hole 8' x 8' x 5' deep keeping the top 24" aside from the sub material.

It was only a matter of shoveling the sub material into the concrete mixer and let it turn over and over, the rocks acted as ponders pulverising the clay and sand as well as them selves into a very alluvial texture.

The trick then was to keep adding more material till the larger material spewed out of the mixer into a barrow and were taken away leaving behind the pulverised clay and clean sand.

By placing a 3/16" sieve on top of the wheelbarrow and slowly sieving the pulverized clay and sand as it came out of the mixer and discarding the material that did not pass through the sieve I ended up with a brew  that would not rip my hands to bits while handling and tampering it into position.

To test the ratio of clay to sand I used a  long tall clear glass bottle half filled with the sieved product and then filled with clear water, 5 minutes of good shaking separated the clay from the sand it was only a matter of waiting 24hrs to see how the sand went to the bottom first leaving the lighter clay to settle on top of it. By measuring the depth of the clay to the sand a percentage ratio can be formulated. In this case I did not have to add either clay or sand. I found on the net. that 15-20% clay is the ideal ratio any more clay shrinkage will take it's toll. (This indeed is correct)

Anywhere or time you can work concrete you can work this mix especially as Calcined Gypsum generates a lot more heat than Portland Cement as it sets due to it's unique quality of expanding while setting.

I will post some pictures for you once I get them uploaded to Imageshak.

Regards,

Megamont

Mini Oven's picture
Mini Oven

Here and more put in three,4,5, hours ago under the same name.
This spammer is sneaky.
Until Floyd or JMonkey can fix it, PLEASE, everybody zap the spam with negative points!

JMonkey's picture
JMonkey

Got to get to work in about 10 minutes, but I'll kill all the spam I can see until then. Floyd will be on in 3-4 hours, and he can kill the account itself.

Floydm's picture
Floydm

Thank you, JMonkey.

I killed the account and banned the IP address. I also deleted all of the rest of the spam that I could find.

Mini Oven's picture
Mini Oven

mini

Edouard's picture
Edouard

I realize I'm late to this discussion but Nancy ... go here


Flickr: TechnoPeasant's Photostream


... and would be delighted to discuss with you my experience, the ins and outs and what worked and what didn't. It was easy, while being pretty physical but the finished product was worth every effort. 


Write anytime. Cheers

Father Kitchen's picture
Father Kitchen

Nancy, I want to build an oven too, but was deterred last summer by a heavy class schedule and right now by an injured shoulder. However, regarding fuel efficiency, I read someplace (Scott and Wing, perhaps) that the retained heat oven approaches the theoretical maximum efficiency possible for a wood fired stove. And when I baked in one on Guam, I was amazed at how very little fuel it actually needed. (The local oven master at Gef Ta'go fired the oven with only about half a dozen dried coconut palm fronds with their stems, and we baked a dozen beautiful loaves.) What does make a difference is the thermal mass. If the oven is designed to bake several successive loads, it has to be thicker and it takes much longer to heat up and uses a lot more fuel. If it is designed to bake one load, it can be relatively thin, and it reaches cooking heat with very little fuel. In fact, I've seen photos of terra cotta ovens designed for individual loaves in Europe that don't look like they are much thicker heavy garden pots. So fuel should not be a worry. 

Susan's picture
Susan

Good to see you back, and hope to read about your recent adventures.


Susan from San Diego

sourdough greg's picture
sourdough greg

I see this thread started years ago, but having just finished my mud oven a few days ago, I had to chime in. I also used Denzer's book. Best how-to book, IMHO.  


I decided to try Denzer's recommendation to try and use no newly purchased materials. Since I have an older house that had "creative" garden edging when we bought it, I had not only plenty of flagstone, but enough firebrick for the hearth floor as well as an arched door. I scavenged sand and gravel from some long completed construction sites, and dredged a little more sand from a nearby creek. With a 42" hole needed to get the frost line, I needed quite a bit of fill material, but had leftover concrete from a sidewalk I had replaced with paver bricks (more former garden edging). I had enough clay from the hole to build the entire oven.


Total cost was...$0, absolutely nothing, except for many many man hours of labor, as my wife and two teenagers all agreed it was "Dad's project".


First pizza test was last night. Not bad, but the crust wasn't as crisp as I expected. After rereading Part of Denzer's book, I realized I had probably used too much fuel, and had prevented the oven from getting as hot as it could. Tonight, much better results. Nice, thin, crispy crust. Very tasty, and I'm so happy with the result that we're having people over for Labor Day and having a non-traditional Labor Day pizza party!


Although Delzer's book is excellent, one thing I didn't figure out until after almost completely finishing my oven was that I had not used enough sand in my cob mixture, so had some hefty cracks to fill. No disaster, but some extra work that could have been avoided.


I haven't done any final "waterproof" outer layer, a necessity here in the Chicago area. Any recommendations? A roof is not an option, per my spouse. I"m thinking of trying the lime plaster method. Does anyone have any experienceand/or tips in this area?


I LOVE my oven. I can't wait to start breadbaking in it. I really built it for bread, the pizza aspect is just a fringe benefit.