Clay Oven


This post is all about our clay oven, which I built two years ago. You really can’t beat a pizza from a wood fired oven. It has being getting a lot of use lately now that the kids are that bit older and the weather is getting better. We have being using the clay oven a lot for entertaining guests and seeing who can come up with the most unique pizza. I also have a batch of homebrew fermenting in the shed, which should be ready in a few weeks. It’s a recipe based on a beer being drank before prohibition. Homemade beer and pizza is a fabulous way to spend a summers evening.

Hilda, I hope this guide is helpful.

You will need a sturdy heat resistant base for your oven. I made a large plinth using fire bricks. These are the yellow bricks in the photos. Underneath the fire bricks I have a foundation of upturned glass bottles and sand. This helps to spread the heat evenly. Once complete your oven will reach temperatures of 300C plus. So it is important not to skip this stage. I sourced my fire clay from a specialist in Athy Co. Kildare. Two years ago I had to travel that far to get the fire clay as it wasn’t available in Drogheda. You might be able to get some off of your local fireplace maker. The rest of the ingredients are easy enough to come by.

Ingredients :

3 25kg bags of fireclay

3 25kg bags of building sand

1 small bale of hay

Plenty of water for mixing

A large sheet of plastic or tarp


Before you start with this project make sure you have a perfect foreman to over see the job.


Make a plint for your oven and outline the size you wish for.


Make a mound using damp building sand. This will be the foundation for the clay. I used some spare bricks in the center to give extra support for the chimney pipe. Once the clay is dry you can remove the sand. The clay could take up to a week to dry. So be patient.


Cover mound with damp newspaper.This helps the wet clay to stay put rather than going straight on to damp sand.


I made a scaffolding to hold the weight of the sand in place while I built up the clay wall. Otherwise it would have collapsed under pressure.


Lay out your tarp and start to mix the clay. Do this by stamping it all together. Have a bucket of water on at hand to help with mix. This job is hands on so don’t be afraid to get stuck in. The first layer is equal parts fire clay and sand. There is three layers in total. The second layer is the same just with the hay added. The second layer is an insulation layer. The third is the same as the first. Try and get your clay mix to a dough like consistency so that it is easy to work with. Not to wet or dry.




Take the clay mix in your hand and start the build. Take your time with this, as it is very important that you make a neat smooth finish. Because this first layer is going to be in direct contact with the heat source, ie: the fire. Start from the bottom and work your way around the base finishing at the top.



Once you are finished the first layer let it dry off a little before you start the second layer. This will help with the bond.


Use a knife to make score marks over the first layer. This will make a rough surface allowing the next layer to stick, insuring a tight bond.



Again, let this layer dry off a little before adding the third layer. As on the the previous layer, score this one too prior to adding the final layer.


As you can see your oven will really start to take shape now. At this stage your foreman will probably check in to see if everything is going to schedule. Even if they are off sick with the chicken pox.


As the clay starts to harden you can remove the scaffolding. Do this with care so as not to damage the hard work you have done. The third layer is both insulation and aesthetic. You are free to put designs or insert tiles into the soft clay now to give your own personal touch. I myself went for a smooth finish which I intend to paint, someday.


While the clay is still a little soft you can use a knife to cut away the exact measurement for your door. I made a wooden door backed with heat resistant foil. But you could always get a metal flap down door fabricated. I decided against that because of the children. It goes without saying that they should never be near the oven but a metal door will hold the heat longer. Running the risk of an accident. Do what works for your home, though.

Now the clay oven will be pretty hard at this stage. I estimate that this should take about week in total, drying. Obviously depending on your climate, but with Irish temperatures in April this how long it took ours. You can remove the sand from the inside now. Don’t worry about any newspaper left behind as this will be burnt off at the first fire up.


I would let the oven dry out again for another week at least. Don’t rush it at this stage. Also don’t be alarmed if you see any cracks developing as the oven starts to harden. This is fine. Clay is a natural product and it is difficult to control an even drying time. If you have any large cracks it could indicate an uneven finish while making your wall. Try filling these with some wet clay.

Fire it up!


Even after all your hard work, without a good chimney your clay oven will remain redundant. I went for two and a half metres of stainless steel piping. This piping is the same as that used on wood burning stoves.

As you can see the temperature on these ovens can get very hot. Even with the door open this oven is sitting comfortably at 190C.


I hope this guide has been helpful to you all. I am not a builder or tradesman at all and look what I achieved. All I did was watch some youtube tutorials and make sure I had my homework done. Don’t be put off by the time it takes. In the end you will have an amazing oven you can entertain friends around.




1 thought on “Clay Oven

  1. Thanks so much for showing me the whole construction process. I will show it to my husband. I think he more or less has a design in mind, but seeing how other people have done it always helps. He hasn’t begun yet as he has just finished building the greenhouse. Maybe these pictures of the oven and the pizza will spur him on.

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