Author Topic: Building an out door pizza oven- cob vs masonry??  (Read 3827 times)

Offline Travis

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Building an out door pizza oven- cob vs masonry??
« on: July 24, 2015, 01:26:57 PM »
Has anyone  built an out door wood fire pizza oven? What are your thoughts on cob vs traditional masonry? Any recommendations on proven building plans or books to read?
I have been reading that cob ovens create tons of smoke but are cheap to build. My husband and I also took Ernie and Erica's Rocket mass heater building class so I am familiar with mixing the cob. Traditional masonry ovens look great but I heard they can be expensive and I do not have masonry experience. I have some options open for discount brick.

Thanks,

Nikki

Offline r_w

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Re: Building an out door pizza oven- cob vs masonry??
« Reply #1 on: July 24, 2015, 02:04:18 PM »
Cob doesn't last in the rain, but it cooks better than a masonry stove IMO.

I lost my first cob oven to an unusually wet month. 

I am working on an affordable fortified cob mix using local clay plus fire clay and high temperature mortar.  Getting a shell that is waterproof and doesn't crack from expansion has been a bit of a challenge.

Offline Travis

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Re: Building an out door pizza oven- cob vs masonry??
« Reply #2 on: July 26, 2015, 07:47:36 PM »
Good to know. 

I did see that Ernie Wisner, in one of his videos, says he covers his oven with a tarp when not in use.  But I'd prefer to not have tarped equipment in the yard. 
 

Offline Cedar

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Re: Building an out door pizza oven- cob vs masonry??
« Reply #3 on: July 26, 2015, 08:15:54 PM »
There are alot of cob ovens here in Oregon I have seen They have a pole structure with a roof over them.

Cedar

Offline mountainmoma

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Re: Building an out door pizza oven- cob vs masonry??
« Reply #4 on: July 26, 2015, 08:52:49 PM »
I had a cob oven at my last house (so built it 18 or more years ago) I built it directly outside of the kitchen door, on the cement porch slab. This way it was mostly protected by the roof overhang of the house. The door to it opened away from the house.

People would sometimes ask " aren't you worried about it right next to the house ? Isnt it a fire hazard ? " And, I would remind them that I had a stove actually in the house, in the kitchen (the kitchen range, gas stove) oh yeah -- anyways, the thick cob walls are like your range sides , they do not get hot on the outside, the INSIDE of the oven s where the heat is.

I never got to plastering mine, and not only did it last years, but it was darn hard to destroy when the time came, when I sold that house, the buyers agent convinced me I need to take it with me, my brother with a sledge hammer had trouble destroying the cob oven.  I also had cob benches in the yard, completely un plastered and exposed totally to the weather, these werent usable during the rainy season, but then dried out and were used all summer. I never tarped them. This cob oven was the largest I had ever built, for a while I did natural building as a hobby, I had decided I needed it large enough to fit 2 cookie sheets in side by side, I dont know why, I do think it was bigger than I needed.

Do not mix cement products into a cob mix. But, what you can do which will weatherproof is to plaster with a lime plaster. A lime plaster with a bit of roof would be best.

The way I was taught to make them, there are different layers in the actual dome, so the innermost layer is heavier in clay, then there is an outer layer that is heavy on the straw, so more insultive and havent seen cracking on the outside.

when I did a free consultation for our grange on this a few years ago, another thing came up. You need to think of the whole environment. So, at the grange, it is in a lower income area of a town here and one of the realities of the property is that children who live nearby roam around unattended -- so we decided that free range children needed to be a design consideration, and a brick oven whill hold up better when being climbed upon

Offline caverdude

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Re: Building an out door pizza oven- cob vs masonry??
« Reply #5 on: July 27, 2015, 12:19:20 AM »
A useful addition to a cob oven might be an air intake pipe that you drop down into it so that as air is drown down through the pipe it is heated to provide a more efficient burn. Then when you are ready to cook withdraw the pipe, cover the hole and remove coals. Put bread in and cook. I'd also think a smoker oven thermometer might be cool addition.

Offline r_w

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Re: Building an out door pizza oven- cob vs masonry??
« Reply #6 on: July 27, 2015, 06:03:44 AM »
Smoker thermometer won't work.  I used an infrared thermometer in my stove and could max it out, over 1000F.

Offline Travis

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Re: Building an out door pizza oven- cob vs masonry??
« Reply #7 on: July 27, 2015, 06:42:02 AM »
@mountain Momma- We are in Northern Wisconsin so half the year the pizza oven would be covered in snow the summer months are extremely humid, so extreme cold (-30 windchill) and extreme heat and humidity would that make the cob brittle?

Offline mountainmoma

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Re: Building an out door pizza oven- cob vs masonry??
« Reply #8 on: July 27, 2015, 08:11:22 AM »
I dont know of any cob ovens in such an extreme environment. If I were you, I would do more research, but look at earthen building in general, how it fares. I cannot imagine that a cob oven would want to be literally buried in snow all winter.

Earthhaven is in North Carolina, which is a large permaculture intentional community, I have stayed there, it is very humid. Lots of earthen buildings doing great.

One thing about cob oven is that all it costs you is time, and enough fre bricks to be the oven bottom. If it fails you can do something else

Offline caverdude

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Re: Building an out door pizza oven- cob vs masonry??
« Reply #9 on: July 27, 2015, 11:25:15 PM »
Smoker thermometer won't work.  I used an infrared thermometer in my stove and could max it out, over 1000F.

Infrared Thermometer? Have a link to one for sale?

Offline mountainmoma

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Re: Building an out door pizza oven- cob vs masonry??
« Reply #10 on: July 27, 2015, 11:32:22 PM »
A useful addition to a cob oven might be an air intake pipe that you drop down into it so that as air is drown down through the pipe it is heated to provide a more efficient burn. Then when you are ready to cook withdraw the pipe, cover the hole and remove coals. Put bread in and cook. I'd also think a smoker oven thermometer might be cool addition.

Cob ovens that I have bult do not have a seperate air intake pipe, there is one opening, and it is the door. You fire it and the thermal mass holds the heat, you rake out the coals and then put in the food. Not having holes in the dome for an air intake pipe makes the  whole thing stonger. A pipe opening while make a weaker structure.

ANd, I wasnt clear enough before I think, I said " lime plaster and a bit of roof " for protection form elements. The bit of roof means, you have some type of roof over it, the lime plaster helps with wind driven rain and such

Offline caverdude

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Re: Building an out door pizza oven- cob vs masonry??
« Reply #11 on: July 27, 2015, 11:42:04 PM »
Cob ovens that I have bult do not have a seperate air intake pipe, there is one opening, and it is the door. You fire it and the thermal mass holds the heat, you rake out the coals and then put in the food. Not having holes in the dome for an air intake pipe makes the  whole thing stonger. A pipe opening while make a weaker structure.

ANd, I wasnt clear enough before I think, I said " lime plaster and a bit of roof " for protection form elements. The bit of roof means, you have some type of roof over it, the lime plaster helps with wind driven rain and such

no they don't come with that pipe, I was just suggesting an idea I had to make burn more efficient if one would want to..