How To Build A Pizza Oven Hearth

andyclifford How To Build Pizza Ovens 14 Comments

Introduction: Building a Pizza Oven Hearth

Building a good pizza oven hearth requires a good set of building skills and tools. However, there are also some great benefits to building your own hearth. Firstly, the potential for saving money, especially if you can source cheap materials from a sale or at your local or online auctions.

Most importantly, this type of project brings families together. However, you should be prepared, it is hard work and takes time. Although, when you finally relax to eat wood fire pizzas with your friends, you will see it's worth the effort.

Let's get building...


Project Overview: Pizza Oven Hearth

  • First you will need to plan where you want your Pizza Oven Hearth. Choose a place where you get good afternoon sun if possible.
  • Mark out the base and dig the footing.
  • Choose whether to go with the full box or have a front storage facility. 
  • Build the block foundation based on your choice.
  • Choose whether to build your own chimney support from blocks or use our free standing support rod for your chimney. 
  • Pack Your full box or install ply on your hollow box. (Add temp supports underneath)
  • Build an internal box 50mm thick, the same shape as your laid-out granite cooking surface, be sure to add 4mm to EVERY side for expansion capacity. Allow the gap for the granite down the center as well. 
  • Box out and pour the first stage of your pizza oven hearth. (See diagram below)
  • Pour the second stage of concrete and finish edges around internal and external boxing.
  • Install your new Piazza Pizza Oven on top of our Piazza Pyro Tape Sealer.

Considerations Before You Build

  • Lay out your granite to make sure you are constructing the correct size base for your Pizza Oven Hearth - triple check this.
  • Ensure you use our KIM agent and you have it handy before you begin concreting.
  • Do not place thick steel reinforcing directly under the center of the oven or it will move too much. Instead, you can use steel mesh reinforcing as shown in the diagram below. 
  • Make the concrete ratio for the oven hearth pour 4:1 builders mix to cement. Keep the mix quite dry if you are planning to install the granite on the same day. Note: Add a teaspoon of dish wash detergent to the water and you’ll have a much improved mix.
  • Agitate and mix the brew thoroughly to stop the water from rising to the top during the drying period.
  • You can settle the granite straight onto the concrete on the same day. Or wait a day or two and bed the pieces down with some trade- mortar. Whatever you feel more comfortable with.
  • In both cases, a bit of Chemkey painted undiluted on the back of the granite improves adhesion.
  • Note: Have the granite/concrete finish falling slightly away from where the oven will be sitting. A 5mm fall is enough.
  • Match the spacing between the two granite pieces of your cooking surface with the gap width which has been laser etched. 
  • Do NOT grout the granite tiles inside the oven, if you have tiles come right over the top of the pizza oven hearth, only use grout on the outer area. 
  • You will need to cover the newly poured hearth and granite for 2 days to allow it to dry completely. You can then place your oven onto the hearth.
  • For your first light up, you will need to run the fire at a low heat for about 4 hours. This is to drive out all the water in the hearth and is to be done before your first cook up!

The Pizza Oven Base Build

Stage one: Instructions

  1. Mark out an area to match your pizza oven base size and dig down to solid and pour a little footing 200mm wide.
  2. Lay your blocks on this footing with Trademortar.
  3. Fill blocks with concrete at 6:1 and allow to dry. [This is important as when you tamp down your hard-fill inside the base it could unsettle the blocks if not dry]
  4. Fill base with hard-fill and pack down. {If you are installing a storage cabinet then rather than hard fill use some 10 ml plywood to box and pour concrete on. Let the ply rest on the blocks 25 mis all around. This does not need to be removed after concrete has cured. Support well so it doesn't sag]
  5. Build the block chimney, approx 10 courses high. It acts as a support as well as looking attractive. You can support the flue with a backing rod if you don't want this chimney affect. Order from Piazza.
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diagram of piazza pizza oven hearth and block base on white

Pizza Oven Hearth Build

Stage Two: Instructions

  1. Box and pour top pad 125-200mm thick with 4:1 concrete - Reinforce with HRC. (See notes below regarding 2 Staged Pour)
  2. Your pour will be carried out in two stages - first stage will come to 50mm below the top line. Here is when you will insert the ceramic blanket into the wet mix.
  3. Place ceramic blanket in wet concrete approximately 75mm below granite line. The Ceramic blanket should be slightly larger than oven perimeters, this comes with the kit. 
  4. Work out the area that will be required to house the granite cooking surface. This surface comes in two pieces when you purchase your Pizza Oven Hearth DYI Kit. Once you have the dimensions, make a box with a depth of 50mm to allow for the hexagonal granite cooking surface and 15-20mm of mortar. You can lay the granite straight in if you don't want to build a box, just ensure you are confident to commit to it. 
  5. The second pour  will be with the 50mm granite box (or granite tiles) sitting in position and you will bring the pour near to the top of the perimeter boxing, and the finished surface. This depends whether you want to use a plaster veneer or not. If you do not want to use a plaster veneer, bring your pour to the finished height. 
  6. When hearth is dry, lay granite in hollowed out area with sand and cement at 3:1. Leave a little room around the outside edge of the granite and the plaster veneer for expansion. This could be grouted or sealed with a sealant.
  7. Once the mix begins to congeal, before it goes hard, you can arias the edges and also clean the lines with the back of a trowel around the box insert and outer edges.
  8. Important: Cover newly dried hearth for two days to cure. 
Need Help?

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Comments 14

  1. Exceptional post however I was wanting to know if you could write
    a litte more on this subject? I’d be very grateful if you could elaborate a little bit more.

    1. Post

      Hi Rene

      We will be posting more info this coming year on our site and also our youttube channel – Piazza Pizza Ovens. Watch this space

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