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Question about wood under a cob oven  RSS feed

 
Terry Mac
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Location: California
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So we are building a cob oven with a cinder block base that is hollow to hold our wood. I have seen some images of people using a board on top of the base but covered in cob and providing the platform for the oven to sit on. Nowhere can I find anything about what kind of wood, how it should be sealed or prepped. Any suggestions? Thanks!
 
Jay C. White Cloud
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Any wood really will work for this application, even the conifer species. As for sealing, I use a traditional blend of tung and flax oil, that is mixed with citrus oil, pine rosine and bee's wax. Don't use big box store linseed (flax) oil as it is more petroleum based dryers than good oil.

Brush on and leave for 24 hours in warm weather, 48 in cool.


A 50 mm layer of cobb mix on this as a bedding for your brick or stone cooking surface. Just REMEMBER to have at a minimum 150 mm between the wood and the oven 'hot zone.' Now you are ready to build as you chose.

The method above is a basic outline with minimums, and not a design spec. The oven should have another pavillion structure over it if you are going to use a wood base for the oven otherwise all materials need to be masonry and your oven will also be subject to weathering and degradation if not covered, even if build with only masonry.

Regards,

jay
 
Jay C. White Cloud
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Any wood really will work for this application, even the conifer species. As for sealing, I use a traditional blend of tung and flax oil, that is mixed with citrus oil, pine rosine and bee's wax. Don't use big box store linseed (flax) oil as it is more petroleum based dryers than good oil.

Brush on and leave for 24 hours in warm weather, 48 in cool.


A 50 mm layer of cobb mix on this as a bedding for your brick or stone cooking surface. Just REMEMBER to have at a minimum 150 mm between the wood and the oven 'hot zone.' Now you are ready to build as you chose.

The method above is a basic outline with minimums, and not a design spec. The oven should have another pavillion structure over it if you are going to use a wood base for the oven otherwise all materials need to be masonry and your oven will also be subject to weathering and degradation if not covered, even if build with only masonry.

Regards,

jay
 
Terry Mac
Posts: 3
Location: California
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Thanks Jay! That's sort of been my thought but wanted some confirmation from those who have done it before.
Terry
 
K Nelfson
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For a cob oven, which will probably not last forever, a wood base is fine. But why not build a masonry base? If time and budget allow, obviously. A stone base would certainly have a longer life span than wood.
 
Terry Mac
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Location: California
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Because my masonry skills are very basic and I want the hollow circular base to store my wood. I have to bridge the top somehow. If you have suggestions on how I create a masonry top I am all ears!
 
Jay C. White Cloud
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I would have to agree technically K. Nelfson, but "lasting forever is a relative thing."

If a well designed cobb oven is protected from the elements with a pavillion or other structure that effectively mitigates water, and the design is good, the cobb is a proper blend, and the foundation is well made. One built of just wood timber on stone plinth, and cobb could last a minimum of 2000 years, so I really don't see the need for a heavy stone foundation for an oven.

Many forms of architecture are a tad out of balance, especially today's modern architecture, which has virtually no balance between it and the environment at all. The oldest undocumented timber frame (once a bread bakery) now destroyed by war in Syria, was 7000 years old. It was built of cobb, timber, and stone plinth foundation. The oldest wood frame structure, sitting on stone plinth, is a Japanese timber frame, which is 2000 years old and still stand strong. There really is no need to go to the expense of building a masonry foundation for a cobb oven, other than personal aesthetics and motif, if your only goal is longevity.
 
K Nelfson
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Terry Mac wrote:Because my masonry skills are very basic and I want the hollow circular base to store my wood. I have to bridge the top somehow. If you have suggestions on how I create a masonry top I am all ears!


I made a brick arch on my first pizza oven. I didn't even know how to mix mortar before I started the project.

http://www.instructables.com/id/Wood-Fired-Brick-Oven/step2/Base/

I suggest you take the aesthetics seriously. Whatever you do will be with you for a long time

By the way, field stone is free and usually available at a farm near you.
 
Jay C. White Cloud
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Hi K.,

I agree that aesthetics are very important, and as you say, can be with you a very long time indeed. The brick arch is a very nice touch! I like masonry arches, and have done several in dry laid stone for a wonderful affect to the general project. These masonry elements are much more time consuming to do and also, whether materials are free or not, they are costly in the labor, as well as, fiscally. (Very beautiful though, and often worth the effort, if the general theme is heavy and stone based.) Depending on the design, the nice element about all wood and cobb oven units, with only stone at grade level, is ease of construction, and speed of removal/relocation should the need arise. As for aesthetic, because of the 'plastic' nature of cobb, it is much more yielding to artistic endeavors than stone or fired ceramics, from a time and ease of manipulation in the medium. I love stone and as a stone carver lean that way often, but practicality is the forefront of most domestic "cobb oven projects." . I would also add, that of the stone arches I have done, several have been retrofits to what Terry is currently considering, so the masonry can always be an augmentation for a later time should the desire come forth.
 
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