Pizza Oven Build Part 3 – The Oven Floor

In part 2 of the oven build I utilised my bricklaying skills and built the base structure and now it’s time to actually get onto building the oven floor!

Materials Required

This is where the costs start to mount up and it’s worth being realistic about how much things cost. Note that prices are from my 2016 build so may have changed:

You’ll also need general things like mixing buckets, trowels, etc which we’ll already used earlier, plus an angle-grinder for cutting bricks.

Slabs rather than concrete

Most guides will tell you to build a wooden form (a support structure) and then pour a solid concrete top but knowing how much it cost for the foundations and how tricky it could be I decided to try something else and used concrete slabs instead. These only cost around £5 each from B&Q and as you can see I had already factored this in with the lintel support.

pizza oven brick laying

I’ve opted for a less traditional diagonal facing oven and so I cut the final slab with an angle grinder to get a neater finish. Going for this design is a little trickier than just a square structure but it works better with the space I have and should be a great focal point in the garden.

Pizza Oven Build Part 3 - The Oven Floor 1

Insulation Layer

Concrete doesn’t  perform well under high temperatures so I’d be asking for trouble if I just put my fire bricks directly onto this base and so we need an insulation layer. This is the first part of the build things didn’t go 100% according to plan but that’s part of the fun eh?

Perlite is a low density volcanic rock which is used for it’s insulating properties in building and also gardening. It’s really light but a great insulator and so our insulation layer is made by mixing 5 parts perlite to 1 part cement. You can get a 100 litre bag for less than £20 on Amazon which is great value.

Manually mix the perlite together with the cement so there is no white left and then add a little water to bind it all together. Don’t be tempted to use a cement mixer or any too rough and it will break the perlite down.


Most pizza oven build guides talk of making a wooden frame, pouring in the mix, and letting it set hard. This is where is didn’t work for me.


I poured in the mix, levelled it, and then left it to set for a few days. When I removed the wooden form I expected the insulation layer to be rock hard but whilst most of it was, some, especially around the edges, was quite crumbly and reminded me of Coco Pops! Not what I expected and it could be down to not enough water, not enough cement, or something completely random.


My solution now was to build a brick surround and this seems to have worked out fine. We can’t lose any of the mix and it’s all pretty firm now and pretty solid. In hindsight I could’ve done this in the first place.

The Oven Base

This is one of the most important parts of the build and not an area to scrimp on. As mentioned in the ‘materials’ section at the start of this post I purchased 45 fire bricks from eBay at a cost of £1.50 each totalling £67.50 but these arrived on a pallet and there was an extra cost of £45 for that. These bricks measured 230mm x 114mm x 64mm and it’s important to note the 64mm thickness. There are some bricks out there at the same cost and with free postage but these are half as thick so are a false value and will retain less heat.

If you can get these for free then amazing! But it’s the one area I didn’t want to skimp on.

Pizza Oven Build Part 3 - The Oven Floor 2

Your bricks will need to be arranged in a herringbone pattern when viewed from the oven mouth entry and this is so that your pizza peel doesn’t catch on the edges of bricks…. plus it looks very nice too!

Once you’ve worked out where your bricks will go then you will want to put a dry levelling mix down of 50% fire clay and 50% sand and then you can start your oven base! This mix is basically a heat resistant mortar. You can use a wet mix too but dry allows for you to move bricks around without whilst you’re working on your pattern.

herringbone pattern

Make sure the bricks butt up well against each other and use a wooden or rubber mallet to knock them into place. You’ll also want an angle grinder to cut the bricks for edging.

cutting bricks
odd sections
all thats left

As you can see I was a couple of bricks short and so used the offcuts for a few of the edge sections.. These won’t actually be in the oven so I’m not as worried about these but make sure the bricks in the cooking area are nice. Those few brick bits on my bench are actually all I had left so I was pretty happy at my guess work!

The finished oven base

So here it is and the next stage will be building the actual dome! Building a pizza oven certainly isn’t a quick or easy job but it’s pretty fun!

finished oven floor

10 thoughts on “Pizza Oven Build Part 3 – The Oven Floor”

  1. Having a go at building my own pizza oven and your guide has been great! I have a (potentially stupid) question about the leveling mix underneath the fire bricks; If it’s just a dry mix, what’s the need for including the fire clay in the mix? Will sand alone not be sufficient?
    Having not bought fire clay before, I’m not sure its consistency so maybe I’m being ignorant of it’s purpose here.

    Any guidance much appreciated!

    • Hi Alex, great to hear you’re building your own pizza oven!

      The mix was dry but I’m sure that there will be some moisture in the sand and in the perlite mix below that will cause the fire-clay/sand mortar to set a little.

      To be honest though, you’ll will probably be fine with just sand as it is just for levelling. The great thing about building your own oven is that you can go off grid a little with some aspects, and this definitely isn’t a major aspect of the build.

      I’d love to see how it’s going so feel free to ping me some photos at [email protected] if you fancy.

      Good luck.

  2. It was probaly the wood pulling the moisture from the perlite/cement that made it crumbly on the edges. For anyone reading wet the wood well before adding the mix or line the edges with polythene and pull off after.

    • Cheers for the tips Chris. It’s all a learning experience and to be honest I like the brick border which was put there by necessity but now looks like I meant it!

  3. You can also wrap the wood with plastic food wrap or packing tape. I used Melamine boards and put the slick side towards the mix. Came out pretty smooth.

    • Could I put a poured fire grog and fondu base in instead of fire bricks on top of a perlite insulated 40mm base on top of of my concrete worktop

      • H Allan, to be honest I’m not too sure. There are plenty of different ways of doing these things, and I just know the way that I did it.

  4. Hi- just beginning my 1st build. Have read Simon Brooke’s book which suggests a 80cm dome with a height of 40-45cm. My dome will be approximately 100cm (approx 20% larger) is it safe to assume that I should increase the height by the same % ie. 50ish cm? Also I will be using powdered fireclay i)is it ok to mix in a cement mixer for puddling with the sand and ii) is the ratio the same – 2 parts sand to 1 of clay (dry weight) or should I reconstitute the clay first? Thanks in advance for any advice!!!🙂

    • Hi Richard, on the next post there are some formulas for dome heights etc. A 106cm dome would have a height of 46cm, so hopefully that helps.

      As for the fireclay… to be honest I’m not too sure! Hopefully you’ve found the solution!


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