Hello. Guidance Welcome!

[stonecutter]

Re: Hello. Guidance Welcome!

Yes I'm already on the plastic hunt - some sort of pond liner is what I'm looking at.

My main gripe with the concrete is cost. I'm definitely going for a 'good enough' rather than 'best practice' approach. Reuse of what I have lying around is my main aim. Aesthetics does come into it and also a dislike to working with concrete but I'll use concrete if I have to. My dislike of concrete is compounded by spending the last few months digging up and removing a load of it from my garden. I'm having a hard time thinking about bringing a load back in!

I'm confident I can solve the moisture issue. It's the structural issue I'm worried about at present, particularly the added stress to the retaining (dry stone) wall. I may need to rethink the location, in which case I'll need to build a foundation and base anyway.

Ok, I'm guilty of skimming your op and missed that you are placing your oven on the dry wall. I would advise you to place the oven base on the front of the wall. Without getting into all the specifics of why (there are many) the soundness of your slab or base..is partially dependent on the dry stone wall for support and stability. That's a big problem...unless it is properly built. So it means you have to build a stand, instead if using the wall.

I can't say with 100% certainty that the wall is unsuitable based on a picture, but I'd have a good idea. If you put one up, I'd be happy to look at it.

[atb trev]

Re: Hello. Guidance Welcome!

Thanks Stonecutter. Great info.

[atb trev]

Re: Hello. Guidance Welcome!

Yes I'm already on the plastic hunt - some sort of pond liner is what I'm looking at.

My main gripe with the concrete is cost. I'm definitely going for a 'good enough' rather than 'best practice' approach. Reuse of what I have lying around is my main aim. Aesthetics does come into it and also a dislike to working with concrete but I'll use concrete if I have to. My dislike of concrete is compounded by spending the last few months digging up and removing a load of it from my garden. I'm having a hard time thinking about bringing a load back in!

I'm confident I can solve the moisture issue. It's the structural issue I'm worried about at present, particularly the added stress to the retaining (dry stone) wall. I may need to rethink the location, in which case I'll need to build a foundation and base anyway.

[stonecutter]

Re: Hello. Guidance Welcome!

Great info thanks.

I thought if I'm making a base. Why not make it structurally sound (enough) and also insulating too. Never enough insulation is No. 2 on my design guides.

I'm a complete novice by the way and am making this up as I go. Hence validating my thoughts with people who know what they're doing. I couldn't even begin to start such a project without the goldmine of info on this forum.

All comments are v much appreciated.

My soil is very dense clay. It looks like you could dig it up, make a pot and stick in in a kiln. Indeed, this project started out as a cobb solution as I've got so much clay, but I've been won over by the better longevity and performance of the brick ovens.
There's not much top soil on the bank and although I may not dig all the way down to the clay, I would not anticipate much movement. It's pretty compact. My main worry would be heave with the clay or the extra weight putting too much pressure on the retaining wall, but I'm not sure a concrete foundation would avoid these issues either?

The insulation isn't necessary for the slab on the ground. And placing a slab on top of insulation is asking for settling problems. Did I mention that it's useless?

Clay can be tricky, there's a lot of variables there. If you have a deep clay layer then I would shoot for a minimum of 8" base material...well compacted...well draining.

[boerwarrior]

Re: Hello. Guidance Welcome!

Trev

if your concern about concrete is aesthetic, you can build a slab that is just big enough for the oven so that you won't have a big slab to look at. Pizza ovens are very, very heavy and you want a very solid base that won't shift. The other thing you need to be careful of is moisture. If there is any way that moisture can leach into your floor or dome bricks then you won't be able to dry your oven out sufficiently and the oven won't work. So do your best to keep wet soil separated from the oven base and use moisture barriers (like heavy duty polyethylene plastic)

[atb trev]

Re: Hello. Guidance Welcome!

Great info thanks.

I thought if I'm making a base. Why not make it structurally sound (enough) and also insulating too. Never enough insulation is No. 2 on my design guides.

I'm a complete novice by the way and am making this up as I go. Hence validating my thoughts with people who know what they're doing. I couldn't even begin to start such a project without the goldmine of info on this forum.

All comments are v much appreciated.

My soil is very dense clay. It looks like you could dig it up, make a pot and stick in in a kiln. Indeed, this project started out as a cobb solution as I've got so much clay, but I've been won over by the better longevity and performance of the brick ovens.
There's not much top soil on the bank and although I may not dig all the way down to the clay, I would not anticipate much movement. It's pretty compact. My main worry would be heave with the clay or the extra weight putting too much pressure on the retaining wall, but I'm not sure a concrete foundation would avoid these issues either?

[stonecutter]

Re: Hello. Guidance Welcome!

Thanks for the feedback oasiscdm.

I'm not planning to put brick directly onto the soil, but am trying to avoid a solid concrete foundation due to a personal distaste for big slabs of concrete and to keep to the no 1 design goal - keep costs down. I'm digging back a bank so effectively I'll have soil at waist height behind a retaining wall.

My plan was to use some concrete fence posts I have to frame a layer of bottles + sand. Then lay the ceramic fibre board on that. However, I'm thinking the sand will wick any moisture out of the soil and straight into my ceramic board. So I'm thinking of adding a paving slab layer on top of the base as currently designed ( I have some of those lying around too).

The only concern then will be whether this is structurally sound enough to build on. I may give this a go then stack my bricks on the base for a week or two (I'm in no rush) to see if there is any movement.
If that fails I can easily remove and go with a concrete foundation.

Can I ask, why do you want to build on top of glass bottles? That's something low cost builders use as an insulation layer under the hearth, not as the base for the whole oven.

If you don't want a slab, you need to remove the organic soil down to subsoil, then use well graded aggregate compacted in lifts. If your area is prone to a lot of rainfall and frost, then you want large aggregate with no fines, and daylight the water so you don't create a bath tub.

My current oven has no concrete slab, just a base of compacted granite dust 1/4"-fines. Around here, under the 3" of topsoil is pure sand, so it's free draining. The stand is drystone and has been in place about 18 months, no settling. The key is a well compacted base, the drains.

[atb trev]

Re: Hello. Guidance Welcome!

Thanks for the feedback oasiscdm.

I'm not planning to put brick directly onto the soil, but am trying to avoid a solid concrete foundation due to a personal distaste for big slabs of concrete and to keep to the no 1 design goal - keep costs down. I'm digging back a bank so effectively I'll have soil at waist height behind a retaining wall.

My plan was to use some concrete fence posts I have to frame a layer of bottles + sand. Then lay the ceramic fibre board on that. However, I'm thinking the sand will wick any moisture out of the soil and straight into my ceramic board. So I'm thinking of adding a paving slab layer on top of the base as currently designed ( I have some of those lying around too).

The only concern then will be whether this is structurally sound enough to build on. I may give this a go then stack my bricks on the base for a week or two (I'm in no rush) to see if there is any movement.
If that fails I can easily remove and go with a concrete foundation.

[oasiscdm]

Re: Hello. Guidance Welcome!

Hmmmmm building on soil interesting I would at least use footings as even smaller ovens weigh heaps.maybe a very thick road base well compacted would work. But unless you intend making it portable maybe with metal frame I would look at builder beware.

[atb trev]

Re: Hello. Guidance Welcome!

Hi boerwarrior,

In fact I found your thread earlier today and read about your 70 pizza +bikers extravaganza. That was a project and a half! V. Impressed! I'm currently minded to make a 30/32" oven largely based on your experience so thanks for all the details you have provided. Presumably you don't have any problems with space for roasting and such like?

30/32 seems to be the sweet spot for me in terms of space available, fire time and retained heat. The main design goal of my oven will be low cost, but I won't skimp on insulation as that seems to be absolutely crucial.

I'm currently head scratching on how to avoid a concrete base (I don't like concrete) but I'm not sure how I can avoid moisture creeping in from below as I'm planning to build directly onto soil.

Thanks to others for the pointer to homebrew mortar- I've come to the conclusion that is the way forward for me.

I've got a bit more time to think now as a kids treehouse project has jumped the queue so the pizza's will have to wait so please keep comments/suggestions coming.

[boerwarrior]

Re: Hello. Guidance Welcome!

My oven is a 32 inch Pompeii. It is extremely well insulated. I can heat it to Pizza cooking temperature in 1 hour and 15 minutes. I doubt that you will be able to get a 36 inch to Pizza cooking temperature in an hour - but I may be wrong!

Theoretically, I can just about get two pizzas in my oven at the same time - but I have found this to be unnecessary. I can cook a pizza in 2 minutes. I have had a party for 70 people where I cooked about 50 pizzas.

My build thread is here: http://www.fornobravo.com/forum/f8/3...nia-19283.html

[atb trev]

Re: Hello. Guidance Welcome!

Thanks for the comments.

Glad there's nothing absolutely crazy in my plans so far.

For the base:
I've got some concrete fence posts hanging around so I can frame the bottles/straw/sand quite securely. If I make sure all the bottles are the same size and packed tightly I'm hoping I won't see any movement.

Brick.

Yes cutting the bricks will be a pain. I'm prepared for that, but what might be a problem is running out of bricks if the cuts don't go well. I was planning mainly to bolster cut them in half as has been suggested which worked quite well for building a brick BBQ. I'll also have access to a grinder which may help smooth off the rough bits and help shaping bricks to fit specific gaps.

The bit of advise I'm really hanging out for is size of dome advise. If I go for say a 30" internal oven space - is that going to be sufficient to cook 2 pizzas with a fire too? If I shrink the dome, are there any other considerations I need to be aware of other than making sure the entry is shrinked proportionally?

[moderator]

Re: Hello. Guidance Welcome!

Trev!

Thanks for signing up to our Forum. I have moved your thread to the Pompeii conversation thread. This way, people following that thread can offer their insights.

Good Luck

[david s]

Re: Hello. Guidance Welcome!

I think you'll have a hell of a time cutting those bricks. You might be better off just cutting them in half with a brick bolster and placing the rough end out. Use plenty of cheap home-brew mortar and wooden wedges which you can remove as you go.

[jeeppiper]

Re: Hello. Guidance Welcome!

Welcome Trev !

The only thing that concerns me is your plan for the base. First, you will need to figure out how to empty all of those beer bottles! Just kidding.

My concern is that you are putting the fiber-board on an unstable foundation of beer bottles, straw, and sand. Im no expert, but it seems like that might move/shift underneath your oven floor. A concrete slab to support your floor would be more desirable.