It all came about because we had a wonky wall that needed either rebuilding or propping up, and not knowing anything about building granite walls at the time we decided to prop it up by building a pizza oven against it. Who wouldn’t! 😜
We investigated how to do this on the net, read some books, asked around, watched videos, saw one in action (@cotnaecoretreat) and then basically we had a go…
We built a platform of granite and lime mortar – as we have no shortage here, everywhere we dig we hit granite – and back filled it with rubble as it grew.
It’s about a metre cubed.
We then insulated our base with a couple of rows of glass bottles and sand.
Once this was done we were ready for our oven floor. Conveniently we were removing night storage heaters from our farmhouse and the red fire bricks inside (we had read) were perfect. Again these were laid with sand and levelled carefully with gentle tapping.
The next bit – the oven itself – was the fun bit and we like to share our fun so we invited a load of friends round. 😄
On top of the fire bricks, dead centre on our plinth we built a small dome of wet sand. This is your oven size and we can’t remember the exact dimensions but probably about 1/2 metre circumference. On top of this you apply wet newspaper… read on to find out why…
Now to make the cob. If you live in a clay area you’ll have no problem but we don’t. Our subsoil doesn’t have enough clay probably because we live near the top of a granite hill, so we bought in some local clay and added this together with our sub-soil and water.
A huge tarp on the ground is best and a few volunteers in bare feet to work the mix. You want the consistency to be like a burrito when you fold in the side of the tarp. Not too wet. Not too dry.
When you’ve achieved this you apply an even 3-4inches on top your newspaper. Score the surface before leaving it overnight (at least) to go off.
After which make another mix, at least double the amount this time though and you also add some straw for binding. This time you apply 6-7 inches all over the previous layer and score the surface again.
After another wait we then bravely cut the door out of the two layers.
When we reached the newspaper we then carefully scooped out the dome of sand. We knew where to stop inside the dome when we reached newspaper! Cunning eh!
Once we had got this far we left the oven to completely dry out before firing it up. The newspaper then burns off.
You need to start a gentle fire to begin with to help dry from the inside.
It was probably a whole season before we decided on a finished look. W e wanted to keep it natural so in the end went for a natural lime render mix and topped it off with embossed designs of the elements. (You could do mozaic, or whatever whacky finish you want. Or you could even put a roof/shelter above.)
Lime render should have been ‘waterproof’ but we had quite a bit of cracking as you can see from the repairs we needed to carry out below. We think this is because we left it too long to put the waterproof (lime) coat on and water already got in and made surface cracks, and these eventually came through the lime too:
We scraped out the cracks and then filled them with a clay slip and let this dry.
This summer though, for our second round of repairs we are hopeful we’ve solved the cracking issue, because this time we added horse hair to a first thin lime render mix…
and then applied a further thin lime layer on top. We had to do it in two stages as the first was quite hairy!!! (👀) Our oven is now back to its former glory with the elements firmly re-instated and after at least a half dozen firings and loads of rain we have yet to have any cracks return.
It takes about two hours to heat up and the about 2 or 3 min per pizza to cook!!! It’s a great community builder. We love it and recommend everyone having a go!