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runnerduckfarm 08-10-2009 09:58 AM

Constructing Oven Floor
Hi All,
Boyfriend & I going back and forth on oven floor. Step 3, structural base of reinforced slab OR fabricated metal pan. He wants to do metal plate and then insulated concretemix with FB says much easier than constructing form and pouring another slab. I am worried metal plate could potentially warp if it gets too hot. I could not find any threads on use of metal pan for base.

If someone could cut to the chase for him...what is best method to form oven floor?:confused:

bernerdog 08-11-2009 04:57 AM

Re: Constructing Oven Floor
I hope your boyfriend is right because I`m well along on building on a welded steel frame made of 3"x2" heavy tubing. I think (hope) that it is overbuilt with four pieces across bottom in addition to the outer rails/frame pieces. It weighed about 400+/- pounds and I couldn`t move it after I built it until I got 3 young nephews together . I laid in fairly large pieces of thin steel plate and then filled the slightly less than 3" space with verm/portland which I topped with 3 FB boards before laying out the floor. I`m on fifth or sixth ring and have been climbing all over it w/o apparent trouble. I didn`t want the hassle of the block base and would have had to hand mix because of site. I think the verm and board layers distribute the weight and both resist compression. This can`t settle things for the two of you because:1--I`m not even done and 2--who knows how well it will all stand up and last, but I`m liking the looks of things and am highly optimistic . John

Ken524 08-11-2009 06:17 AM

Re: Constructing Oven Floor
Hi Runner,

I'm not sure I understand what you are planning. Are you wanting to put a piece of metal on top of a block stand? Then lay down the insulation and build the oven?

runnerduckfarm 08-11-2009 07:07 AM

Re: Constructing Oven Floor
Yes, looking to place 3/8" plate over block stand then form sides with welded angle and place concrete/ verm mix on top of that. this means base would just be around 3 1/2" vs 7 1/2". Trying not to have to form up and use cement board etc. Want plate to act as support and base. Plan on adding a center support to middle of plate. Our base is somewhere around 70" x 78" close just cant remember exact dims as I am at work!

RTflorida 08-11-2009 10:23 AM

Re: Constructing Oven Floor
Provided you insulate the hearth properly, warpage due to heat should not be an issue. My oven uses "old tech" insulation under the hearth (4" of vermicrete) and my recent all day scary fires (around 8 hrs of continuous burn) only resulted in my hearth support slab reaching about 135 -140 degrees. That is as extreme as I will ever get in my fires...and 140 degrees won't warp heavy steel.

Using the right gauge or thickness steel and the underlying support would be the only concerns.


Neil2 08-11-2009 01:24 PM

Re: Constructing Oven Floor
I would have thought a reinforced concrete suspended slab would be cheaper than an equavalent metal plate.

Having said that, a 4 inch layer of vermiculte should insure that the metal does not over heat. Most steels can take up to about 700 degrees Fahrenheit before they start loosing tensile strenght.

RTflorida 08-11-2009 01:45 PM

Re: Constructing Oven Floor
That plate is going to be are going to need the whole neighbood to lift it in place (promise them pizza when you are all done - beer too)


karl 08-11-2009 02:03 PM

Re: Constructing Oven Floor
Your oven will be heavy. And the plate will probably sag in the middle? Have you calculated the displacement/sagging? If the plate sag it will definitly transfer forces into the oven brick structure. Could mean its more exposed to cracks. If the plate is well supported (no wide spans) i would not worry.

regards from Karl

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