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Hello - challenged by build on a slope

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  • Hello - challenged by build on a slope

    Hello, I am new to this forum and new to the art of oven building. I live in Japan about 1 hour south of Tokyo in the countryside.

    I've been lurking here a little while and will continue to read the posts here and in the subforums to learn more from the vast experience accumulated by all the members here.

    About my own build(plans). I want to build a relatively simple dome oven - probably reinforced homebrew mortar mix. I've got a small collection of fire bricks and cinderblocks salvaged from old houses and my father in law. That's okay for a start but I am realising a lot more will be needed. It is a long project and I will go about it gradually.

    I need to ask questions to the community here to minimise errors and regrets afterwards. One of my first and fundamental (excuse the pun) questions regard the construction of foundation and base of the oven.

    I have attached a photo below. As you can see, I am planning to build on a downward slope. There is no other choice since all our land slopes. I've spent the last couple of days digging through topsoil and through very rich and dense clay soil. The hole for the foundation (160x140cm) is now about 60cms deep at the top end and 30cms deep at the front. There will be a big challenge to address with regards to drainage since after rains the area below the oven does get very wet. We rarely get any frost here (zone 9) in the winters, so at least I don't have to worry about that.

    I plan to pour gravel into the hole, maybe about 10cms, and then pour a reinforced foundation of around 10-15cms. The hole itself is not entirely level, but I plan to pour the gravel to level and place the concrete form on top of that. I guess I imagine that rainwater will be able to flow under the gravel from the backend of the oven through the front that way, but I'm not sure since it's the first time I try to build anything of this significance.

    If additional drainage is better I was thinking to run a drainage pipe from the front left of the oven hole and down (se photo, black drain pipe laid out from left corner of foundation hole). Do you think this approach to drainage makes sense, or do you have any other recommendations or things I should do before starting the foundation to ensure the foundation doesn't fail?

    Thank you sincerely for any advice you may be able to provide.

    Last edited by Yokosuka dweller; 09-26-2019, 05:54 PM.
    My build:

  • #2

    Since frost is not an issue you plan looks fine from my end. I would extend a perforated black pipe into the gravel sub base to ensure water can egress out (basically what is called a French Drain)

    As far as cast oven. Look at or reach out to DavidS of Townsville Queensland Australia, he is our casting expert and can guide you well on a cast oven.

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    • #3
      Thank you very much UtahBeehiver for your advice. I will extend a french drain from under (or almost at the end) of the slightly sloping subsection under the foundation downwards to get excess rain water drained away.

      And, when I am ready I will check info from David S (from downunder) to learn more about cast ovens, sequence, design and things to be careful with.

      My build: