The Fresh Loaf

A Community of Amateur Bakers and Artisan Bread Enthusiasts.

Earth oven construction, part 2

breadnerd's picture

Earth oven construction, part 2

Continued from an earlier entry....


We let the first layer dry a few days, and some fairly big cracks started to form. I decided to pull out the sand to give the oven more room to shrink as needed, and to help it dry out faster. I cut a smaller door than the final size, you can see the final door scored into the surface:


We ended up letting it dry for a couple of weeks due to rainy weather and other activities. It was covered with a tarp and opened up when the weather permitted to dry out. Next came the second layer. The first layer is just sand and clay—the second is cob: sand and clay mixed with straw.


The second layer goes on much faster, but as it's 6 inches thick you use up a lot more material as you go. We made LOTS of batches of this.


Almost there:


Refining the doorway:


Our door, made from glued-up 4 x 4s, and shaped with a sawzall. Did I mention I have a very handy assistant?


We lit some small fires at this point to aid in drying, and after a couple of weeks started using it. The first few attempts had a big learning curve, and I think I joined the fresh loaf soon after that and documented my later bakes.


The oven was built in May and June, and we left it without a final protective plaster because we were undecided on what to do. We would cover it with a tarp when not in use. Finally, we decided just to make a roof over it, so there is no final plaster layer. It made it through a winter and another summer without much damage. Here’s the final oven with it’s roof:

Many thanks to Kiko Denzer for a great book--its a wonderful way to give wood-fired hearth baking a try without a huge amount of investment (well, if you don't count your time!). I also have the Bread Builders book which I found useful as well, I just didn't have the right location and finances for a masonry oven, and I think after a few years using the "mud hut" I will know better my needs and desires for any future ovens.



mkelly27's picture

Thank you for putting this together for all of us to view.  It is very informative.  You are in WI. are you not?




Two wrongs don't make a right. Three lefts make a right

susanfnp's picture

I agree, extremely informative.

Did you find that the cracks in the first layer did not end up mattering?

Also, did you find that when you were mixing the mud you could keep it fairly well contained on the tarp? The place where I will be building my oven is on a very steep hill and the only flat place I have to work is on the deck that abuts the oven. I'm not crazy about the idea of getting mud all in between the cracks of the deck, etc.


breadnerd's picture

We were able to fill in the cracks with the second layer pretty easily. I was a little worried that there would eventually be bits falling off in the interior, but so far that hasn't happened--I have knocked pieces off the doorway from use, and we'll probably repair that eventually. Maybe a brick doorway next time?

If you had a big tarp, you could probably keep it contained on a deck--or better yet work on one tarp with another one underneath to catch spills, as we found we would pick up the tarp to mix the cobb like a cement mixer. We stomped and mixed in our driveway, and then used a wheelbarrow to get to the oven, which is also on a steep hill. Keep in mind you'll have piles of sand and earth/clay to deal with too.

One thing about hills--it's a good use of space to stick the oven on, but it's kind of a pain to work there--both in construction and firing/baking! Just be sure to figure out how to have a level workspace for loading loaves etc. We now have a bench next to it and lots of places to hang tools, and it's a lot handier.

There are a few sites I looked at A LOT when building mine, so I'm glad to add to the archives. Some I used a lot are:

(not updated any more, but some great photos and recipes

lots of good pictures


Good luck! 

Mini Oven's picture
Mini Oven

I can relate.  What about a large piece of bottom priced lenoleum, it might hold out better than plastic tarp and can be abused.  The steep hill reminds be of a kiln I once built into a hill.  Can use your hill and semi bury the oven?  The hill itself might make a great insulator.  Have you tried making a fire there and seeing which way the wind blows?  

Thanks Breadnerd, I'm enjoying your blog.  

Mini O

susanfnp's picture

Thanks for the tips, Breadnerd andMiniOven. My oven will be contiguous to a deck we are currently having (re)built so I will be able to stand on the deck for loading the oven and otherwise working. Unfortunately it looks like this construction is a long way from being finished so I may have to wait until next year to build the oven :-( Meanwhile I'll have to content myself with Breadnerd's great photos.


sphealey's picture

It looks like you filled in the well with rock of various types, then topped that with sand and set the hearth bricks in the sand. Correct?

Have you experienced any settling of the rock fill and/or sand causing the hearth bricks to shift (esp vertically)? Did you do any special agitating/tamping procedures to settle the rock and sand down in the well?



breadnerd's picture

I did tamp the sand a lot, mostly with my feet!  I know the book mentioned using a layer of tinfoil, or else a thin layer of cobb to keep the sand from settling.  I can't remember if we did the tinfoil or not!  The new edition has a lot more suggestions for this part--including using glass bottles as insulators just under the sand to prevent heat-sink.

I have had a little shifting of my hearth, but not enough to cause any problems.   Sometimes I get a loaf where you can see the edge of a brick on the bottom crust--I find that kind of endearing, ha ha!  I noticed some of my overhanging bricks at the mouth are a bit loose since they are suspended--we have a few ideas to fix that eventually. 

In theory you could reset the hearth bricks, since they are not mortared.

pumpkinpapa's picture

Great timeline breadnerd, I always love seeing how others build, it completely fascinates me to no end!

I too have the loose bricks in the doorway and have been thinking of either applying a clay slip over them to bind them or building up some kind of wood frame or even some more cob just under them.

I find I have no skill with wood at all, or the time (mostly the time) to enjoy my oven and finish the door properly. It's a nice hard maple door about 4 inches thick that needs proper tools to be worked properly.

gavinc's picture

Thanks for sharing your oven construction.  I've only just found your blog entry, but assumed you might have had more than a casual interest when you left a comment on my blog recently.

Has the oven weathered OK?




mredwood's picture

I was not able to view photos they were unavailable. Sad I bet it looks great.


friar120's picture

I would like to read part one but can't find it.  Thanks, Sandi H.