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Mud oven construction - foundation and first layer

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breadnerd's picture
breadnerd

Mud oven construction - foundation and first layer

I finally got up the gumption to move my construction photos over to my flickr account. Here they are in the entirety, I tried to make the titles fairly self-explanatory:

http://www.flickr.com/gp/7541655@N03/aX31kR

 

Here's a condensed version with some commentary:

First off is the foundation. Our frost line in in theory 48 inches, so we dug down quite a bit. We hit a VERY large rock, which made us decide the hole was big enough, and which we figured would act as a foundation in itself.

http://farm2.static.flickr.com/1012/1443314626_31ba338401.jpg?v=0

 

Next, we filled the hole with gravel and started building a foundation from rather unattractive landscaping bricks we already had from another project. We added a layer of lava rock for insulation, Kiko’s new edition has a lot of better ideas for this, but this has worked okay for us.

http://farm2.static.flickr.com/1410/1443314822_1f6502d8de.jpg?v=0

 

Next sand is added, packed, and leveled, and we laid the oven floor bricks. A string was used to draw a circle as large as we could fit on the floor, as our guide for the sand mold form.

http://farm2.static.flickr.com/1367/1442450837_2025385af8.jpg?v=0

 

The sand form took a lot longer than I thought it would, but it turned out nice.

http://farm2.static.flickr.com/1110/1443315018_c94673ba68.jpg?v=0

 

Because of this, we didn’t get very far with our first layer before dark, but you can see the width of the walls, and how compact it was. We were probably overly persnickety with this first layer:

http://farm2.static.flickr.com/1319/1442451223_365f1a3e72.jpg?v=0

 

We covered it in plastic, and resumed the next day.

http://farm2.static.flickr.com/1331/1442450183_71089d3c3f.jpg?v=0

 

Final first layer, wacked with a 2 x 4 and scored for the next layer to stick:

http://farm2.static.flickr.com/1162/1442450281_d233d47f01.jpg?v=0

 

 

more to come....

 

 

Comments

ehanner's picture
ehanner

Breadnerd,

Really great job documenting your construction. You make it seem so easy! I have two questions.
1.) Did you eventually change the opening from the first one you show? it looks like the outer opening is quite a bit larger in the final version. What did you end up with?
2.)Does your oven burn OK regardless of where the wind is from? Kiko mentions the opening is best if the prevailing wind blows into the oven opening. I'm on the fence about a chimney.

Thanks,
Eric

breadnerd's picture
breadnerd

1) Yes, I cut a small hole at first just to get the sand out and let the whole thing dry some more. I think you can see the scored final size. I wasn't quite sure how the cutting would go and thought if I screwed up or dinged it up getting the sand out that I would have a second chance at it.

 

2. Yep so far it seems to burn quite well. Mine faces roughly south which is the prevailing wind in summertime here. Of course in winter it can be the opposite. I find once the oven warms up a bit you get that circular draft movement going and all is well. I don't think I need a chimney, but it will be interesting to see what Scott says about his.

One thing about siting--I think I obsessed about all the possible spots (that if anything made me procrastinate building) and most of us are kind of limited in where we can put them anyway. One thing that helped me was asking another builder how hot the oven got--I was worried about combustibles etc. Turns out, the exterior doesn't get that hot during the firing--mine is actually is warmer about an hour after the fire comes out. Certainly without a chimney mine blows really hot out the front for a few feet, and right around the doorway but that's about it. So that really helped me to site it a lot closer to a fence than I thought I could, and I have no concerns about heat damage--I even have plants growing quite near it and grapevines on the roof structure and they are fine.

 

I do tend to avoid running the oven on super windy days (20-30 mph), just like I would with any outdoor fire--just to avoid any potential problems should a stray ash or coal escape. I want to be a good neighbor!

ehanner's picture
ehanner

Breadnerd, I see photos of pizza and bread baking with a small fire burning in the background. That isn't really necessary is it? Unless you wanted to cook all day at high temps like in a commercial setting maybe a small fire would help.

My sense about all this is that people build a larger fire than is needed and get the oven hot, wait for it to settle out and stabilize while all the thermal mass equalizes to "normal" temps.

Eric

breadnerd's picture
breadnerd

I have read if you want to keep your oven pizza hot for a long period, you can keep a small fire in the back. I think that's what commercial wood-fired pizza places do, plus it probably adds some smokey flavor as well. I find I can bake a few batches of pizza that will bake easily in 3-4 minutes, and i'm sure I could do lots more if I had the need. I mean, the last batches might take 10-15 minutes to bake, but who would care? :)

 

You're correct, I do tend to build a hotter fire than is needed, and let it cool down. For one thing, it does stabliize the temps and makes for a really long lasting oven heat--ie, mine will stay over 400 for hours, and in the 300s for hours more. This is great if you want to do lots of baking, you can do your pizzas, then sourdoughs and lean doughs, and then even more sandwich-type breads (or, say, a chicken or roast!).

 

Also, realistically for me, it's easier to overshoot the temp and let it cool down, then it is to have a too-cool oven that won't stay hot. I did this a few times on my first firings. I'm slowly learning to guage how long to let the fire go, but it's not an exact science. I'm learning to time my final rises to allow for the extra cool-down time, which is easier than rushing the fire for loaves that are ready too early :) It does make for a slightly longer day, and a bit more wood, though I find I mostly let the coals burn down longer than I did at the beginning, that's really where you get some quality heat that soaks into the oven walls and floor.

Alfie's picture
Alfie

For whatever reason the pictures were not visible.


My neighbor and I are very interested in construction details.

DougMagic's picture
DougMagic

I have been very interested in the cob ovens. I live on a peninsula in the Gulf of Mexico and Tampa Bay so, our "soil" is just sand and shell, no clay for miles. Should have gotten interested before I sold my truck!


You did a wonderful job documenting the procedure, you should probably send your photos to Kiko Denzer. I hope you enjoy the fruits of your labor!