Forno Bravo Forum: The Wood-Fired Oven Community

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-   -   Deciding on a Base (http://www.fornobravo.com/forum/f2/deciding-base-6203.html)

Allen 02-27-2009 09:32 AM

Deciding on a Base
 
Hi, some friends and I want to tackle making a clay-type oven.
A friend and I made an elevated cooking platform out of locust logs for our dutch oven cooking to minimize always having to bend over to check on the food. Here's a photo taken not long after we had built it.

http://img.photobucket.com/albums/v1...ngPlatform.jpg

Could I do something like this for a clay oven?
There are some beautiful oven designs on this site but I'd rather not use concrete footers and cement block/bricks for the base if I don't have to.
I tried searching for info but didn't really come across anything for this question.

This thread has an oven similiar to what I'd like to try:
http://www.fornobravo.com/forum/f3/h...exas-3397.html

I thought about these types of bases:
A triangular log base.
A base that sits on 4 legs.
A base that is built into the side of a steep hillside with a log base.
A plain old 4-sided log base all made from locust logs.

Was thinking of a 32" to 36" interior dimensions for the oven.
thanks,
Allen

Jed 02-27-2009 10:54 PM

Re: Deciding on a Base
 
Hey Allen,

Any one of the base options you list could be an acceptable solution. The base needs to support the weight of the oven, and although the oven is heavy, any one of these options you list could be engineered to handle the load.

Most of us will choose the cement base (or cement block filled with concrete) because it won't rot or disintegrate over time; the base of the oven will remain stable and in one piece for a long time. Cement creates a solid base, that is structurally sound, that will support the weight of the oven, for a relatively low cost, over a very long period of time.

You can use the wood base, but this will likely be the part that fails on your oven first. It may take decades for the wood to rot, but that will be the reason you will need to spend time and money to either repair or dismantle your oven. If you use cement products, it will likely be something else that fails first before the base gives way....

My two cents....

JED

dmun 02-28-2009 04:22 AM

Re: Deciding on a Base
 
Many people, when they think "oven" think about that flimsy sheet metal thing in the kitchen. Masonry ovens aren't like that. They are really heavy, and rigid. They don't deal with shifting or vibration very well. They can crack, and collapse if they move around. That's why the masonry bases: they are stable and rigid, and they are far cheaper than trying to approximate the same rigidity with, say, welded structural steel.

The oven you linked to had a recycled concrete base: I didn't see a log in it except to burn.

Wood is constantly in motion. Every time the humidity changes its size changes: more against the grain than with it. It warps. Bugs like to eat it. I really can't recommend a structural log base for a masonry oven.

That said, it might be a cool facing material: bolt on logs to your structural base for a log cabin look with a rough split shake roof, and a big fieldstone chimney at one end? I think that would be great.

Good luck with your project.

Allen 02-28-2009 08:28 AM

Re: Deciding on a Base
 
Thanks for the replies.
We want to build this oven (hate to say it) on the cheap.
One of my friends was trying to talk me into cement blocks so maybe that will be the way to go.
Some of the ovens I've seen have two or three runs of cement blocks as a base.
Not sure how to pour a slab on something like that but I'll figure it out.

This link has an interesting oven: http://bensart1.homestead.com/breadovens.html

I may have access to mountain stone so that will give a more rustic look than cement blocks.
Allen

Ken524 02-28-2009 01:56 PM

Re: Deciding on a Base
 
Pouring the slab on the block base is pretty easy. Most any of our build threads have pictures of the process (you can click my "Old Kentucky Dome Thread" link below).

Also, download the "official" Forno Bravo plans for plenty of detail and pictures:
Brick Oven Plans | Build an Italian Brick Oven

carloswlkr 02-28-2009 04:45 PM

Re: Deciding on a Base
 
I agree with dmun, Ken and others about wanting to make sure your base is as solid as possible. Best to avoid wood, that can shift and will rot faster than you'd like. I would not want to experiment with different bases if you are building a fire-brick oven, and investing a fair chunk of change in the materials.

That being said, I suspect if you are making a clay or mud oven, you can probably find alternatives to the tested and true method of a cinder block and poured concrete base. If you're going with 'what's on hand', you might try some third-world construction techniques for your base. Looks like you've got plenty of rocks and/or boulders near that dutch oven cooking stand. Have you thought about piecing together a base out of carefully placed rocks, 'mortared' together with mud and straw? (see examples in my post on Honduras bread ovens.)

Here in Latin America, highways have retaining walls made out of wire cages filled with river rock. Box shells are made out of heavy chicken wire, approximately one meter square, then carefully filled with river rocks or other stone. The cubes are stacked one on another, and make retaining walls that last for years, and hold back incredible amounts of dirt.

You might experiment with one of these techniques. Whatever you do, make sure that it is on as solid a footing as humanly possible, and that the base is level all the way up. You don't want the floor to be on a tilt, or the base to shift because it wasn't build level to the ground. I would also make a solid base, not one with the traditional storage area below. This will give additional strength to support whatever oven you put on top.

Again, cinder block and poured concrete will produce something that will not let you down, and I wouldn't stray too far if you're building a brick oven. But I say, give it a shot!

dmun 02-28-2009 07:38 PM

Re: Deciding on a Base
 
Quote:

Here in Latin America, highways have retaining walls made out of wire cages filled with river rock. Box shells are made out of heavy chicken wire, approximately one meter square, then carefully filled with river rocks or other stone.
This is a really good idea. These things are called gabion baskets and are used for highway construction. They can be made in custom sizes, but probably not on the cheap. Here's a link:

Welded Wire Mesh, Gabion baskets, PVC coated gabions, Mesh Fencing, welded mesh rolls, weld mesh panels, stainless steel, galvanised

gjbingham 02-28-2009 10:42 PM

Re: Deciding on a Base
 
Dmun's caged rocks sounds very similar to how the landscaping firms around here sell landscaping stone by the ton - all caged up and on a palate. From the prices I saw today, a ton of the cheap stuff would still cost more than a concrete block base.

carloswlkr 03-01-2009 05:56 AM

Re: Deciding on a Base
 
True, if you are going to buy the stone, it may well cost more than a base of block and poured cement. But if you've got the time, and rock is plentiful on your property, it might still be one option for doing it yourself and not investing in materials other than the heavy gauge chicken wire.

Allen 04-19-2009 05:57 AM

Re: Deciding on a Base
 
Thanks everyone for the replies. I wasn't around for a bit due to work.
I've got a backhoe rented for this coming weekend to do some work around our place and am planning to dig a foundation for the base.
I am also able to get as much field/mountain stone as I need for the project. For free.

My dad and I built my forge out of similiar field stone, check this out:

http://img.photobucket.com/albums/v161/xm15e2/Shop3.jpg
http://img.photobucket.com/albums/v1...2/DSC_0034.jpg

I feel confident that good sized rocks similiar to what you see in my forge will easilly support a cob-style oven.
Am planning to dig down about 36".

I was using the search feature but couldn't find an answer to some questions.
The foundation will be square.
For a 32" to 36" cob-style oven, how wide should the base be?
I've also got a bunch of 2a driveway stone.
Should I place the field stone on a bed of the driveway stones first?
Or just let them sit in the dirt at that depth?
Was planning on filling the center with dirt and loose rocks.

thanks,
Allen


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