Wednesday, December 30, 2015

Building a pizza oven in a day - Sept 2014.

With our daughter's 3rd year at kindergarten coming to an end, as is traditional from parents - we wanted to give something that would be of use to the school. Having learnt how to make these ovens from Phil Cashman, our ever resourceful & ingenious Permaculture teacher & friend, I put the knowledge to use.

Building materials consisted of clay (from our garden), rice straw, sand, cement and 32 bricks + a used wooden pallet. We had a team of around 20 parents to do the work together.

The first stage I did myself at home, mixing up clay, soil & cut straw, which was dried on the pallet for around 4 weeks. This would make the bottom insulation layer.

The base layer of bricks was laid with cement beneath, as tightly placed as possible, placed roughly in a circle.

Bricks were cut in half and a semi-circular temporary form was used around which an arch was laid, again - using wet cement.

The ratio of the pizza oven's entrance and width & height of the inner dome are critical to making a good oven. There's no chimney with this design.
Here we laid wet sand as a form on which to build the oven on top of. It was laid with wet newspaper over the top when finished, so that the clay walls wouldn't stick to the sand later (newspaper will burn when the oven is first lit).

Meanwhile, the ladies were having barefoot fun, mixing soil, clay & straw with which we'd lay the refractive inner layer of the oven. Somehow the men got the easy labour this time!

And so the first layer went on. Being quite a wet and soft mix, it was necessary to be careful not to lay too much on the sides and more on the top as the layer naturally gravitated downwards.

And the ladies continued....

The thicker insulation layer consisted of clay and straw, which again needed to be laid with more on the top, as it would flow to the sides under it's own weight. 

A final layer consisting of mostly clay and sand was then mixed & laid.

This is how the finished oven looked. The form could be removed before the cement dried. In all it took around 6 hours for 20 people to build together, including stopping for lunch!

It would take around 6 weeks to dry, before fires were lit inside (at low temps to avoid cracking the refractive inside clay & insulation layers) about 3 times. Naturally the oven can't ever get wet with rain.

Weight is around 350kg when dry, but can be lifted onto a small truck by 6 men and transported elsewhere to be used for pizza parties. Cost of building is around $100 - 150 USD. for bricks, cement and sand. I have details of ratios of materials used for the different mixes so if anybody wants to make their own, just ask and I'll be happy to share the info.

Makes delicious bread too!

No comments:

Post a Comment