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Oh Dear - Wish I'd found this place before!

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  • Oh Dear - Wish I'd found this place before!


    First off, I'm from over the pond in the UK and a complete outdoor oven n00b. I'm currently doing my garden and yard area, which has already over run by errrrr,...about 6 months. The missus is made up...not!

    I dreamt up this idea some time ago, so let me explain. We have a very small garden, roughly 7m long by 4.5m wide. A path about 1.5 - 2m runs in front of it between the house. The path is a shared path with the other 5 terraced houses (built 1826 btw). Then there is the house that has a really small courtyard area, about 3.5m long by 1.5m wide. I've attached my garden plans for you to see, it'll make it easier to understand.

    We also have two mischevious black labradors, and the idea was to be able to pen them in the area we wanted, ie indoors, courtyard or garden area, depending on what was needed at the time. The coutyard area is also covered with a timber frame polycarbonate lean-to. We used to have a gas patio heater there, but we found it didn't get used much, as you know, it rains quite a bit over here...hence the lean to, but the then no warmth as the heater is too close to the roof...the dilemma!

    So, I had this idea that I was going to build a brick wall half way across the opening and put an iron gate in. At first I was thinking of getting a chiminea, but the idea developed into a BBQ and then a brick oven type fireplace. Having not found this site, and now reading through it, I'm facing problems.

    Anyway, I appear to have made just about every mistake in the book in regards to design and materials with my oven. Well, to be honest, it wasn't meant to be a proper oven. So I've already built the brick frame, which is one brick wide around (against the exterior wall of the house).

    I'm now in the process of about to create two arches, one for storage underneath (wood) with a york stone slab oven floor, and one at the top for the oven roof. I was about to blunder ahead and poor concrete into a mould I'd made with ply, but I read standard conrete will be poor. I'm also concerned I only have one brick width using regular mortar...hmmm. For the life of me I can't rip down the frame I have built. I'm no brickie and this alone has taken me ages to get right.

    I've a few desing change proposals, and was wandering if I could swing them by you...and sorry for the already long rant/post.
    • Create the lower arch in the mold using concrete and vermiculate 5:1 (will have to use rebar also)
    • Use firebricks as base
    • Insulate against red bricks using fire blanket equivalent - 1 inch
    • Build inside oven space with fire bricks (oven getting a bit small now though)
    • Create top arch using firebricks and set with vermiculate mortar and concrete
    • Finish top with teracotta tiles

    Its going to mean I'm going to have a very small cooking space, but with what I think enought room at the back for the fire, and just enough space upfront for a small grill or pizza. I'd have to keep the fire small.

    The chimney design is another challenge, as it will have to be at the back. I'm leaving a fairly wide vent which will feed into a double sking flue, probably about 2-3 foot tall.

    I think my main concern is that it doesnt all crumble to pieces and provides some warmth in the sitting area and not smoke the crap out of us . Secondary priorities are maybe being able to cook some food in it, ideally pizza.

    If you've got to the end of this, thanks for reading, and thanks in advance for any comments.

    Last edited by timiano; 10-03-2006, 05:25 AM.

  • #2
    design changes

    Please provide more information about your current brick frame. How high have you built it? Have you just framed the base (to the hearth level of the pompeii oven) or have you brought brick up to the top of the proposed oven level? Could you support the base by lining the inside with concrete block? What are the dimensions of your brick frame (how wide by deep by tall)?


    • #3

      Thanks for getting back to me. I've been beavering away in visio for a while putting together diags to show what I've got, and what I've planned for.

      I know the size is really small, but its the only space I have to work with. Lets put it this way, its a bit of an experiment. I just wanted a few comments. As I said, I was originally just going to have the thing with just red bricks and normal mortar, but reading here has made me think it might just fall completely to pieces, hence the rethink.

      Anyway, the plans are attached to this post. First one illustrates the brick wall frame that I have made. The idea is to set a concrete/vermiculite mould to create the arch. Each arch is supported by 3 x rebars through the concrete and into the frame. I then build the inside of the oven using 50mm thick firebricks. The second arch is constructed of firebricks and concrete/vermiculite levelled off to the top.

      Having the firebricks in there really reduces the space to work with, which was small in the first place . When I move to a new house (probably 10 yrs - 29yrs old now btw, so plenty time ) I'll look at having the space for a proper oven like all you guys have got, but until then, I'm going to have to try to make something work, all be it maybe not perfectly.

      Do you reckong this could do a job, ie provide a bit of heat to the living area and use for limited cooking?

      Thanks again



      • #4

        It looks like you have about 20"wx24" deep in the oven itself. That's pretty tight for a wood burning oven, but do'able.

        I can think of two approaches. First, you can make a barrel vault dome (the dome curved in one direction) out of firebrick (or red clay brick), and pour vermiculite into the gap between the cooking dome and the exterior walls. It would work nicely, though it would fit in your tight space. You could make a good fire, then do roasts, pizza, etc., and at the end of the evening you could build up the fire, which would heat the area. It won't get hot like a pizza napoletana oven, but you would enjoy it.

        Or, you could build a traditional wood (of charcoal) fired BBQ. The floor, walls and back wall would be fire brick, but the grill would not have a top. You would have to buy a free-standing grill, or make a space for a slide-in grill. That would give you traditioanal Mediterranean grilling, and an open fire that will heat the area -- perfect for chilly late afternoons. You would loose the ability to make the two-minute Italian pizza, but you would gain a fireplace and BBQ.

        Either way, make sure the inside of the oven is true firebrick or red clay brick. Those will absorb heat for cooking. The vermiculite/perlite mixture is only for insulation -- not the inside of the oven.

        Let us know how it goes.
        Pizza Ovens
        Outdoor Fireplaces


        • #5
          Here in the states, you can buy half thickness firebricks, called splits. What I would do, is glue one inch thick calcium silicate board to the inside of your brick structure, and line the inside with splits. It's not much thermal mass, but you can use thicker fire brick and insulation material on the top and the bottom. I don't see any reason why that wouldn't work.

          James has pointed out that in Europe, you can get hollow terra-cotta lintels, which can be layed in place of the re-inforced concrete layer that you build your oven on. With your undersized oven, I think that would be more than enough to support your firebrick weight. You would need to build up something on the sides to support them; perhaps mortar a layer of concrete patio pavers on the right and left side of your brick enclosure.

          Good luck
          My geodesic oven project: part 1, part 2


          • #6
            Thanks for the responses fellahs

            I've sources some splits, well 2" thick fire bricks and vermiculite, so I'm almost ready to go, just got to pick it all up tomorrow. I'm still going to go along with the oven design and see how it goes. If it doesn't really work, I'll remove the top and go for a BBQ/Fireplace...nice idea by the way.

            One further question please. In terms of chimeney/flue design, I was wandering how big the vent on the roof shall be. I was going to make it the width of the oven by about 5/6 inches and funnel it into a stainless steel flue.

            Does that sound about right, or is it too big. Bear in mind the chimney is at the back of the oven.