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Wood post and Durarock instead of slab - Forno Bravo Forum: The Wood-Fired Oven Community

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  • Wood post and Durarock instead of slab

    I had a huge maple tree removed and want to build my outdoor kitchen including the pizza oven where the tree was. My problem are the large roots I can't dig out. What if I sunk four wood 4X4 and run joist 10" on center and topped it off with durarock. Do you think that's sturdy enough to hold the Pompa oven. I'm pretty sure it is, I guess I am more wondering what challenges this might create.

  • #2
    Im not sure that is a good idea. The bearing pressure on the soil will be extremely high. Let me walk you through it. Not sure how big of an oven you are planning to build so I am making some assumptions here that may be incorrect. If you are building an oven per the FB plans, it will weigh in the neighborhood of 3,000 lbs. The hearth slab will be close to the same weight. So, for this exercise, lets say the total weight is 5,000 lbs. 4x4s have nominal dimensions of 3.5x3.5 which is 12.25 sq. in. 4 of them will give you 49 square inches of bearing surface. This results in a bearing pressure of 102 psi or roughly 14,600 psf (lbs per sq. ft). Without getting into the minutiae of soil mechanics, good soils generally have bearing capacities of around 2,000 psf. See the issue? You could pour 4 spread footings a foot or so square and attach the legs of your stand to them. A simple 12x12 footing under each leg would reduce the bearing capacity to 1,250 psf which is reasonable given decent soil conditions. If you can provide more info about your plans such as oven size, masonry or cast, flue construction, etc. and some photos of the area you plan to build in, we can give you some better suggestions. I would also be concerned about the long term structural integrity of the wood. Wood is a great building material and you can certainly build a stand for your oven out of it, but it will need to be designed very carefully. Concrete is much better for this application. I hope this helps. Let me know if you have any questions.

    Also, welcome to the forum. Lots of great information and folks willing to help.
    Last edited by WarEagle90; 05-08-2018, 11:50 PM.
    Dan

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    • #3
      Rent a (big) stump grinder to get the roots out, then dig down to undisturbed soil, backfill with gravel and pour a slab. You won't regret it. The stump grinder is fun.

      Pizza ovens are meant to last for a thousand years, wood isn't.
       
      My build thread: https://tinyurl.com/y8bx7hbd

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      • #4
        Plus 1 on both the last two comments. A proper base is the core support for your oven, as WarEagle mentioned, these ovens can be very heavy, over a couple tons. So spend the money and get the stump and root removed. You are spending a lot money by building an outdoor kitchen/pizza are. Do it right.
        Russell
        Build Link............... Picassa Photo Album Link

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        • #5
          I don't entirely agree with some of the comments above there is no reason that a suitable sized footing of concrete cannot support timber posts and the oven

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          • #6
            Sure, it can, but why? You introduce a whole lot of present and future problems for what is probably an even trade in the amount of work required. Digging holes through a root ball for appropriate footers (42" deep in our neck of the woods) is a lot of work.
            My build thread: https://tinyurl.com/y8bx7hbd

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            • #7
              Originally posted by Toomulla View Post
              I don't entirely agree with some of the comments above there is no reason that a suitable sized footing of concrete cannot support timber posts and the oven
              Yeah but, here in Oz at least, they'd want to be treated hardwood posts or the white ants (termites to our Northern Hemisphere friends) would destroy all the hard work.

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