The Build Begins!

[gracie]

First delivery of logs today from a local supplier. Filled the log store under the oven plus a 1 tonne sand bag. Really dry, goes up a dream! I've always struggled to get fires going but this stuff is amazing! New favourite treat are giant s'mores! Found some huge marshmallows at Morrisons, a square of Madagascan chocolate...yum!

[raj]

Amazing build.

Do you have more detail on what you did on each layer please. Would be really useful to know. clay to sand ratios etc.

I'm trying to build mine and haven't had much joy yet. What did you use at the front? the curved stone looks really good.

Thanks

[gracie]

Hi Raj,
I can see you had trouble with the under hearth insulation. Did you get that sorted yet? If not, I'd suggest that the clay straw mix isn't the best option. Not sure how much weight it will bear and from your pictures it seems to be in lumps? If you do use it, you will have to squish the balls together more to form a flat layer. I used Foamglas under mine, on top of the concrete slab. Vermicrete is another option as are aerated concrete blocks.
You need to prevent the heat getting into your concrete slab...the glass bottles will hold the heat but if the insulation isn't sound, that heat will always make its way through to any area which is cooler.
The clay straw cob is more suitable for insulating over your dome as you can make it really light ( full of straw) which eventually burns off leaving air gaps...this is what makes it insulating, but the more straw you have, the weaker the resulting product when it's dry. This is why I think it's not the best under the build although I know there are builds recommending it under. Just my opinion!
Here's what I did...
Block work base with lintels supporting concrete paving slabs.
Foamglas layer.
Firebrick hearth laid onto dry sand.
Clay sand dome ( 2 parts builders sand to 1 part " economy terracotta" potters clay).
Ceramic blanket insulation
Chicken wire
Vermicrete

The front arch way is made with reclaimed bricks from the local reclamation yard. I built this just in front of my doorway and then mounded the same clay mix as the dome to bridge the gap between the dome and arch, leaving a gap for the chimney which I made from a flowerpot with the bottom cut off.

I plan to render eventually with k rend to waterproof it.

Hope that helps,
Gracie

[raj]

Thanks for the information.

I'm hoping to do some work this weekend. We re-did the base with clay, sand, straw and sawdust. it's about 5cm high now and looks completely different to the pictures attached previously. It did crack again, so I just compacted it more to join the cracks up.

The aim is to build up a 10cm base, then bottles, then flatten with sand, fire brick on top then the dome. I'm hoping the weather holds out this saturday as I should have some time and possibly some help to continue work.

I'll take some pictures at the weekend and post progress.

[raj]

Hi as promised.

Photo 1 - After almost 12 months mix of 1 part clay, 2 part sand, some straw & some saw dust.



We worked really hard yesterday, mixed 107.5Kg of mix and made the 10cm base as intended.


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It's now covered up, waiting for it to dry a little. The aim is to take off the former around the sides. We spent ages compacting it and trying to get it level, so I'm hoping that this will minimise the cracking that I seem to keep experiencing!



Any help / thoughts appreciated.

[raj]

my slab is 1200x1200mm. what are the dimensions of yours Gracie?
I really like the arch you put at the front as a lip to get in and out of the oven, where did you get this?

[gracie]

Hi Raj, your slab is looking good, well done. My base was about the same, maybe a little longer front to back but not much. The curved front is a half circle kiln shelf. I got it from a local pottery supplier but you can get them online, just google kiln shelf, also called kiln batts.

[gracie]

Quick thought, before you build your dome, comsider how much room you will need for insulation and be sure not to build your dome too close to your brick wall at the back.
Now you're up and running, copy these bits of your build onto a fresh build thread. I am happy to reply to you on my thread but you might not get as many views and replies. Have you decided what style of dome you are going for?

[gracie]

Updated photo with the pergola added. Best thing I ever did...love this oven!

[oblertone]

Very stylish indeed ! My only concern is the height of your flue compared to the pergola; another section of twinwall/flue would cure that though.

[gracie]

Jul 4, 2016 11:34:49 GMT oblertone said:

Very stylish indeed ! My only concern is the height of your flue compared to the pergola; another section of twinwall/flue would cure that though.

Yes, true. It's not quite as close as the picture would suggest and there is a gap in the rafters and no trellis above. Nonetheless, I am on the lookout for a piece of double wall on eBay.

[raj]

Hi all,

Long time since I posted, we managed to almost finish the oven last summer and have done a few burns in it.




Just got to sort the front out and get / make a door and chimney.

Looking for some help please. I can get a fire going and get the upper part of the oven to around 400 - 500 Degrees C, the base of firebrick however remains cold, reading about 150 Degrees C to 200 Degrees C. As the fire dies down and the temp of the base rises slowly but then cools down very quickly, so pizza cooking time is limited. What am I doing wrong?

Any help really appreciated

[cobblerdave]

G’day
You don’t say how long you fire the oven for. I’d say it probably has not had time for the oven parts to equalise in the heat. I’d give it a 1 to 2 hour firing to get that heat to soak in. When you go to cook a pizza a small fire of small sticks on the side means a source of heat to be reflected off the oven dome and radiate back onto you pizza tops. The bottoms will cook faster being in direct contact with the floor.
Regards Dave