The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Earth oven collapse

bobchristenson's picture
bobchristenson

Earth oven collapse

Well this sucks. After many days (and a few dollars) I finished my earth oven last friday. Two layers (thermal and insulation with straw mix). I didn't have time to cover it and it rained heavily today completely collapsing both layers of the top of the dome.

Now what?

I had to buy fireclay and I don't want to have to do that again so reuse is crucial. . Anyone have ideas for rebuilding without refilling it with sand (which would basically be impossible, plus my sand is now gone that I used the first time)? I don't want to tear it all down because I think I'll lose too much clay and end up with straw mixed throughout.

If I have to tear it all down I may just rebuild with firebrick instead of earth.

Any help or sympathy?

proth5's picture
proth5

sympathy, but no help I'm afraid.

So sorry to hear that your efforts came to not much.

 

mariana's picture
mariana

Oh man, that's awful. I am so sorry. I like the firebrick idea though. When I was a child and lived with my grandparents in rural area, my grandparents rebuilt their earth oven every 4-5 years. I don't know why, maybe the ground was shifting slightly underneath with time, but I remember doing it, helping and it wasn't a big deal, not really.

wishing you the best. Don't give up.

 

mariana

Mini Oven's picture
Mini Oven

So now while it's wet... scrape it all into a pile and mix well, don't worry too much about the straw, might even be an improvement!  Whatever is on the inside will burn out with the first fire.  The rest becomes insulation.  Might have to add a little to the outside layer.   Let it dry extra slow.  

A cubic yard of sand can't be that expensive.   You will manage and make it even better!  

Mini

Mini Oven's picture
Mini Oven

out of the clay pile?   Pre-molding the bricks and letting them dry separately, you get faster drying power with the whole oven when it's back together.   Sort of both ideas combined.     ???   With a few pieces of wood, make a frame, press and scrape the "super mud" into it and push out.   I don't know if I would let the bricks dry completely but much of the drying shrinkage would be reduced (in the final oven) and you can pre-form keystone blocks as desired.  :)

bobchristenson's picture
bobchristenson

Thanks for all your encouragement/sympathy everyone.  I was determined not to give up so I've started over.  Step #1??  A roof!!

So this past weekend I built a roof over the oven to prevent rain issues in the future, hopefully this will increase my success rate the second time.  I also think I probably used too much/to large pieces of straw for my insulation layer.  When I tried to move the collapse the straw was HEAVY with water...I think that may have been the source of my problem.  So I plan to remove the straw from the mud  as much as possible (With a pitchfork, I think) and really grind it up using my mower, so I have much smaller pieces next time.  I'd love to use sawdust instead, but I dont think I can find enough.

Anyway, round 2 begins :)

prairiepatch's picture
prairiepatch

That really is too bad about your oven disaster.  I have been looking at possibly building one of those ovens.  The idea of baking bread or anything for that matter in one just seems like such a wonderful idea.  

I hope your second round proves perfectly successful.  You mentioned that you want to chop up your straw.  I wouldn't chop it too much because don't you need the long strands to give your cob its strength.  Sort of like adding rebar to cement.  

bobchristenson's picture
bobchristenson

Well, no one can call me a quitter :)

I've now completed my second complete rebuild of the oven and it's better than it was the first time!  Step 1 this time was to build a roof :)  Once I did that I felt much more confident that it would hold up during heavy rain.

I ended up having to sift ALL my mud through a wire screen to get the straw out and, while that was alot of work, I think it helped mix my mud even more, so that's good.

The only thing I'm not real confident about is that my second 'insulation' layer actually had very little straw in it.  It was almost just a second thermal layer with maybe a tad of straw...I'm hoping this does the job.

My problem before, I think, was that without the straw being really chopped up it got HEAVY when it got wet.  Chopping it is absolutely necessary.  The problem is I didn't have the means (or frankly the energy) to chop it all and try to mix it with my second layer...so we'll see.  I'm hoping it'll hold heat.

Regardless, the end of the story (so far) is happy.  Oven is complete and drying as we speak.  I'll probably pull the sand out next weekend...(that's another thing I changed, letting the whole thing dry before pulling the sand out!)

Floydm's picture
Floydm

Bravo. Looking forward to seeing pictures when it dries out and you fire it up.

Kpolano's picture
Kpolano

My hat off to you to start over and rebuild! It is usually easier the second time around, and you can do all those things that you "would have done". I just wanted to make a note on straw length...

The length of the straw used for the insulation is not too important. The quantity is more important when using it as insulation. Often a straw-clay slip mixture is used for better insulation. I am using wool for mine because it is more readily available and I want good insulation. The better the insulation, the longer the oven will hold heat. If you don't plan on doing three+ rounds of cooking in the oven, then you should be fine.

More on straw. When you are wanting more strength, then you want to keep the length of your straw longer as it will integrate better throughout the mix and give better tensile strength. Shorter straw is better for thinner layers, like the leveling coat or plaster.

All in all, it sounds like you did a good job. Again, my hat off to you.

prairiepatch's picture
prairiepatch

That sounds great Bob.  It really sounds like you got it all figured out.  I can really see having a roof over your head would be alot more comfortable to use the oven in foul weather.  Hey, you went to a lot of work and didn't give up, good for you.  That is beyond excellent.  I can see leaving the sand inside to allow the  oven to dry for a while being a brilliant idea.  Let us know how it goes and if you can include some photos.  Especially some photos of that amazing bread that you will be baking in your new oven.   Excellent work.

bobchristenson's picture
bobchristenson

I also decided to name my oven....I dubbed it "The Little Red Hen" :)  If you know the children's story it's totally the story of my oven and it's future:  I spend days (weeks?) killing myself over it without a single offer of help from friends or family.  But, I'll predict they won't have a problem helping me EAT what comes out of it :)

I even scratched a (pretty sad) chicken outline across it's arch.  :)  Pics below...

 

THE BIG HOLE! (and I thought this would be the hardest part...ha!)

Built a firepit for grilling right next to it!

 

(note that the first 3 pics have a slightly different layout...they were from the first version before the collapse.  Afterwords I changed the brick floor configuration a little)

Floydm's picture
Floydm

Nice.  That looks great.

willwork4SD's picture
willwork4SD

Nicely done! I have recently completed a clay oven by myself. It was a lot of work, but I would do it again in a heart beat. There is nothing better than to fire it up for pizzas, then bread baking. The taste is out of this world, and it is just a really cool toy.

About the insulating layer; you may be able to add a 3rd, thinner layer on top containing wood shavings or straw, mixed with clay slip to increase the insulation. It's worth a try if you find too much heat is getting through to the exterior of your oven.

SD

CelesteU's picture
CelesteU

I have half a shelf's worth of books on earth oven building, yet I've resisted taking the plunge due to moisture issues.  I'm afraid any earth oven I build will simply wash away!  (Life in the subtropics means year-round rain.) Your re-build looks great.  I have decided to save my pennies for a refractory concrete modular oven.

Kpolano's picture
Kpolano

If you build your oven off the ground and give it a good roof with a decent overhang rain will not wash your oven away! Go for it!

EvaB's picture
EvaB

enough and the oven insulated enough that it won't catch fire! It looks a tad low to me, of course its my eye, but will hope it works out for you.

The oven is nice, I'm just waiting for some stuff to move off the lot so I can build one on the level, my back yard where it would be the best spot, is definitely not level. Not to mention where the level spots are its covered with trees. A pain to be sure.

Breadhunter's picture
Breadhunter

looking at your photos, it appears that your wooden roof is vulnerable to flames coming out of the front of your oven. As time goes by, the wood will become more likely to ignite. There are ways to protect a wood overhang from flames. Stu

loydb's picture
loydb

I'd swap out the wood for tin, personally. Great oven, though. But yeah, that is going to catch on fire.

 

Kpolano's picture
Kpolano

The roof does seem quite close to the oven. If you are careful about how you build your fires and watch it while they are burning, you may be fine. After your first experience with rain, I would worry more about the roof leaking. You have no overlaps or even battons that protect from water dripping through the slats. You may just find that you will be having to refinish your oven every year due to errosion from dripping. I would beef up that roof. Otherwise, it looks real sweat and I bet works nice too!

Terri Karsten's picture
Terri Karsten

I really like the way your earth oven looks.  They have an earth oven at Forts Folle Avoine in Wisconsin with a similar shape.

I believe they used sort of woven branch  dome for shaping it.  It has a crack or two in it, but still worked fine last I saw it.

Have you fired yours yet?