12. (E) Second Cement Layer (waterproof, coloured render)

1. In a wheel barrow mix sand, cement, black oxide (1/3 bag), multibond (1/3 bottle). You will mix up three wheel barrow loads in total. 

2. Smooth onto the surface of the oven, working with the trowel for a smoth and bonded surface. 

3. Leave to dry. Cover with tarpaulin if it is going to rain. 

11. (D) First Cement Layer (render)

1. Cover the entire pizza oven (including chimney if you are shaping it) with chicken wire.

2. Mix up cement sand/cement 5:1and apply to the surface. Push it into the chicken wire so it is a solid thick layer. You can build this up to form a shape. 

3. Smooth with a trowel. 

4. Leave at least 24 hours before starting the next layer. Cover with tarpaulin if it rains.  

NB: This can be reasonably rough as your final layer will be nice and smooth.

10. (C) Vermiculite and Cement Layer (insulation)

 1. In a wheel barrow mix your vermiculite with cement in a ratio of 5:1. (Make sure you wear a dust mask). You will need to make three seperate wheel barrow loads so it doesn’t set before you can use it. 

2. Apply by cupping the mixture in your hand and applying to the surface in a thick layer (20mm). Work with a trowel. 

3. Dry at least overnight.Cover with tarpaulin if it rains.  

NB: This layer is quite crumbly so it 

needs a bit of work  with the trowel to 

get it to bond. You can take this layer

up the chimney if you like. We placed 

it to the top of our chimney 

9. (B) Adobe Layer

1. In a wheel barrow mix adobe by combining 5L clay with the previous recipe for refractory mortar (70% clay soil, 20% sand, 10% cement).

2. Smooth this in an even layer over the entire pizza oven. This gives a nice uniform surface to attach the nest layer to and begins to provide some insulation. Work with a trowel for even and smooth coverage. 

3. Dry this layer for at least 24 hours. Use tarpaulin to protect from rain. Again lighting a small fire in the oven after a good period of drying time will help rid excess moisture. 

NB: This layer may crack while drying due to the high amounts of clay. It will not make a difference to the final structure. 

8. (A) Red Clay Brick, Adobe Mortar and Refractory Mortar

1. Using a mallet and cold chisel split a number of bricks in half. These will be used for the small arch and the brick dome.  

2. Mark out with chalk the base structure (see fig.1) and put in place the supporting structures 

(see fig. 3) i.e. ply wood arches, paper mache dome). 

3. In a wheelbarrow mix adobe mortar: 70% clay soil, 20% sand, 10% cement. These are fairly loose percentages. You could use less soil (50%) and more sand and cement if you feel so inclined.

4. Place 1/2 bricks around the outside of the paper mache dome. The inside edges of the bricks need to touch each other (i.e. do not leave a gap between the bricks). Using you fingers, poke the adobe mix in between the bricks. Complete the full dome this way. 

5. In the same way make two arches around the ply wood structures using 1/2 bricks for the small arch and whole bricks for the larger outside arch. At the top of the larger arch leave a gap where you can sit the chimney.  

6. Place chicken wire around the chimney and use the refractory adobe (with higher ratios of cement and sand and a little gravel) to secure it in place. 

7. Remove the paper mache dome and ply wood supports. The structure should be able to hold itself. 

8. This layer needs to dry out for a couple of days. Be sure to keep it dry by covering it if it rains. You can light a small fire in the oven the next morning to help dry out the mortar completely. 

7. Supporting Structures (fig. 3)

6. Pizza Oven Cross Section (fig. 2)

A. Red Clay Brick, adobe refractory mortar (70% clay soil, 20% sand, 10% cement).

B. Adobe (5L clay added to 70% clay soil, 20% sand, 10% cement)

C. Vermiculite and Cement Insulation. (vermiculite/cement 5:1)

D. Rough Cast Cement (sand/cement 5:1)

E. Cement/Plaster, black oxide (500g) and waterproofing agent. (500ml)

5. Fire Brick Layer (Base)

1. Again place a thin layer (5mm) of sand on top of the red brick layer. 

2. Place fire bricks very closely, ensuring there are no gaps between them i.e. they are sitting flat and flush.

4. Red Clay Brick Layer (Insulation)

1. Place a thin layer (5mm) of sand on top of the concrete foundation and level.

2. Carefully place red bricks making sure they are level as you go.

3. Skim a sand/cement 10:1 mix over the top and around the edged to hold the bricks in place. 

4. Let the foundation dry overnight.

3. Concrete Foundations

1. Make a concrete slab 1400 x 1400mm. It will need steel reinforcing if it is sitting on top of a cinder block base. 

Our base was on top of soil and we used existing concrete slabs, then filled the “gaps” with concrete. (See below) 

2. Ensure the concrete foundation is level. 

Here you can see the concrete slabs with the inner measurements of the dome. 

2. Pizza Oven Master Plan (fig.1)

A. Outer Arch (625mm high and wide, depth is the width of a whole red clay brick).

B. Inner Arch (530mm high and wide, depth is the width of  1/2 a red clay brick.

C. Dome (circumference 840mm = radius 420mm)

1. Materials

• Cement (Portland)

• Sand (if you are able to get sand from a quarry, do so, as it will save you a significant amount of money)

• Gravel (fine grade)

• Clay soil 

• Clay (we used 5 litres regular abbots ceramic clay)

• Metal Mesh (reinforcing for concrete slab)

• Vermiculite (100L Bag from ‘Switched on Gardener’)

• Red Clay Bricks 

• Fire Bricks (We found ours on Trade Me. They had been taken out of an old night store heater).

• Fire Clay Flue (or stainless steel flue. Do not use ceramic pipe as it will crack with the heat)

• Paper mache dome: made around a 85cm Swiss Ball (Sourced from Trade Me) using newspaper/wallpaper paste 

• Mallet and Cold Chisel (to break bricks in half from any hardware store)

• Ply Wood (for two arches)

• Chicken Wire

• Trowel

• Black Oxide (to colour final plaster/cement layer)

• Waterproofing agent for cement (we used ‘multibond’ from Mitre 10/Bunnings) 

optional: refractory mortar

NB: We were able to resource/recycle many elements of our Pizza Oven for free or at a very low cost such as clay soil (from our back yard), potters clay (given to us), red clay bricks (given to us), fire bricks (bought on TradeMe, having been recycled from a night store), flue (bought from a second-hand building materials yard), ply-wood (scrap wood pieces), chicken wire (scrap wire pieces). 

Forward - Before You Start

Building a pizza oven takes time, energy, patience, money and resourcefulness. It will take you more than a weekend to complete. One way to cut back the timely process of resourcing the materials, is to buy a pizza oven kit but these are expensive (upwards of $2000). These can be purchased from small businesses online such as TradeMe or from larger pizza oven kit distributers like Authentic Oven in Tauranga. The cost of a DIY home built and resourced oven is less than buying a ‘ready-made’ or kit, however to get real value for money you need to try and find your materials for cheap or free and this could be the difference in paying less than $500 or upwards of $750. 

The following booklet explains how we made our pizza oven. We gained information and ideas from a number of sources and brought them together to create our own product. Internet resources we used often for motivation were Forno Bravo (who make pizza ovens and sell pizza oven kits), The Shed Magazine, ‘Pizza Oven Pleasure Renewed’ Feb 2008 on ISSUU and You Tube Video ‘DIY Wood Fired Pizza Oven Construction New Zealand’ by dunkpaula as well as a number of other blogs and forums online.