Pizza Oven Build

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Introduction: Pizza Oven Build

About: I am a home-maker, parent and architect and I love DIY-ing with my kids and husband in our home in Pretoria.

We decided to bring life to an under-utilised corner of our garden by constructing a brick and mortar pizza oven. This turned out to be great family activity and now that the oven is built, pizza-building is a regular family activity in our home.

Step 1: Preparing the Base

Clear an area for the base of about 1,5 x 1,5 m.

The foundation is a 100 mm thick concrete slab. The finished level of the slab should be about 50 mm above ground level so that ground water doesn’t run onto the slab, which will become the wood store. Level and compact the base area at a level of about 60 mm below natural ground level. Using shutter board or 114 x 38 pine sections, construct a box with inside dimensions of 1420 mm x 1370 mm (1420 mm is the width of the front end of the oven). Position the box on the levelled base area. We threw a 40 kg bag of river sand into the box and compacted it with a hand stamper to create a good base for the slab.

Step 2: Casting the Slab

Mix 2x 40kg bags of ready mix concrete in a wheel barrow or on a plastic ground sheet (mixing concrete by hand can be quite a workout for the unseasoned builder so try mixing one at a time!).

Cast the concrete directly onto the levelled surface inside the shutter box and level off with a plank. (Our oven happens to be over a manhole, which will still be accessible after the build; we boxed the manhole with polystyrene boards to allow a bit of movement around the manhole). Leave the concrete to cure for at least 24 hours before continuing with the build. The shuttering can be removed after 3 days.

Step 3: Building Up the Base Walls

Now you are ready to start building the base walls. We used a cheap face brick for the outer skin of the wall and a clay stock brick for the inner skin.

The base walls required 118 whole face bricks + 22 half face bricks; 90 whole clay stock bricks + 16 half bricks. We used about 6x 40 kg bags of ready builders mix (there was a lot of wastage due to lack of experience!).

Build up the two side walls 9 courses high on the inner skin and 10 courses high on the outer skin. Lay 13x 100 x 75 x 1200 mm precast concrete lintels across the inner skin on a mortar bed (you may need to trim the lintels to fit using an angle-grinder).

Step 4: Building Up Oven Walls and Floor

Now begin building up the outer skin of the oven side walls. Build up 3 courses using clay stock bricks for the outer skin (these will be plastered over at the end). Each course consists of four and a half bricks.

Before going further, screed over the lintels with a perlite mix (trade name PRATLIPERL http://www.pratleyminerals.com/construction-thermal-insulation). This is fairly dry mix that provides insulation and a smooth base for the oven floor.

The mixture seems crumbly and loose but when squeezed in your hand should form a compact lump that holds its form. Pat down the mixture with a float. Once the screed is laid and leveled, cover it with a plastic sheet and allow it to cure for at least 24 hours. If it dries out too quickly it will crumble. Not only is this perlite screed insulating but it also contains minimum cement and can handle the heat (cement will crack under the heat of the fire).

Step 5: Continuing the Oven Walls

Build the inner skin of the oven walls with face brick. A regular face brick is fired at about 1200°C and should easily withstand the heat of the oven - refractory bricks are not necessary. We used a soldier course which is equivalent to three stretcher courses. Make the joints between bricks as small as possible (about 5 mm) to minimise the amount of cement exposed to the direct heat and reduce the amount of cement in the mortar mixture by half (do this for all oven-facing brickwork).

Plot out the curve of the barrel vault on a piece of hardboard on the ground (or other horizontal surface if there are unwanted obstructions on the ground!). Lay out the bricks in a curve with the fire-facing edge of the bricks touching. Butt joints are used so that cement does not crumble in the heat of the fire and fall into the oven.

The height of the oven should not be more than about 500 mm at the apex of the arch. If the roof of the oven is too high, the oven will take too long to heat up and will lose heat too quickly.

Build the back wall of the oven, cutting bricks as necessary to suit the arch.

Note:
Since this particular oven was built against a double brick retaining wall, we only built a single skin on the back of the oven. For a free-standing oven, a double skin wall is necessary to ensure sufficient thermal mass to retain the heat of the oven.

Step 6: Building the Barrel Vault

Cut two matching pieces of hardboard to make the formwork for building the arches of the barrel.

Screw three or four pieces of equal length timber between the two pieces of hardboard to set them about 150 to 200 mm apart. At this point it would be a good idea to drill two finger holes in one of the boards to facilitate removal of the formwork.

Lay out the bricks for the first arch resting on top of the formwork before committing to mortar. Once you are satisfied that they fit, set them in place with mortar.

We used 40 kg bags of builders mix for the mortar but removed half the cement. The archway bricks with butt joints support themselves so the strength of the mortar is not too important.

Since the brickwork in the arch is self-supporting, the formwork should be able to be removed immediately.

Step 7: Completing the Vault

Shift the formwork along and build the next arch butting directly against the first.

Continue in this way until you have built 4 arches. Then begin to build the outer skin of the vault uisng clay stock bricks.

Step 8: Building the Doorway

Build the doorway walls using stretcher course or soldier course.

Plan the formwork for the arched doorway. The size of the door is important – it must be functionally big enough but not too big otherwise heat escapes. The width should be about 500 mm and the top of the arch about 270 mm. Construct formwork similar to that of the oven vault.

Step 9: Finishing the Oven Floor

It is important to do finish the oven floor before completing the chimney and doorway while it is still easy to reach into the oven.

Screed the doorway floor with screed or plaster mix of about 10 mm thick.

Lay dry plaster sand inside the oven; spread it around and smooth off to be level with the doorway screed.

Lay the oven floor tiles loose on top of the plaster sand bed. We could not find traditional terracotta tiles or refractory bricks so - as and temporary and experimental solution - we used contemporary un-glazed terracotta tiles (300 x 300 x 8 mm). These were cheap at R89/box of 10 and we easily trimmed them to fit using an angle grinder. The tiles in the doorway were installed using tile adhesive to secure the layout, while the tiles inside the oven are loose to accommodate thermal movement.

Step 10: Continuing With Doorway and Chimney

Build an arch over the doorway using half face bricks over the formwork.

Begin building up the chimney behind the arch. The actual cross sectional area of the chimney flue is only the size of one brick. It was a bit tricky as the first course of the chimney cantilevered off the doorway walls and required some temporary support.

The taller the chimney, the better the draw so build as high as you can reach or afford!

We completed the front wall of the barrel, cutting bricks as required to fit the arch. (We only built a single skin brick wall in the front and the heat is transferred through very quickly, so a double skin wall would be better.)

Step 11: Finishing Touches

The outside was plastered with perlite plaster (same as the oven floor screed) to insulate it. This required a bit of skill since the perlite mixture is very dry and tends to fall off if not applied correctly – we patted it on by hand. It is preferable to utilise the thermal mass of the bricks to radiate heat into the oven and insulate the outside to prevent the heat from escaping.

The perlite plaster was not very neat so we smoothed it over with regular plaster. We really liked the look of the oven before we plastered it, so we decided to apply brick tiles over the plaster as a finish with red mosaic tiles on the vertical sides. The pebbles on the front were 'something old' from the derelict water feature that used to be where the new oven now stands. You can decorate the outside in anyway that suits you.

We added wooden doors using old palettes hinged on a wooden frame for the fire wood store under the oven and added a wooden door for the oven. The oven door is loose and merely plugs into place in the brick doorway. We use the door when we are baking bread or roasting meat in the oven.

Step 12: Firing Up!

Before we finalised the decor, we built our first fire to check if the oven held. A few cracks appeared which we still haven't repaired but apart from small give-away streams of smoke, the oven works beautifully!

The biggest problem was the floor tiles, which cracked. We replaced the broken tiles with new ones which we trimmed smaller, thinking that the cracks were due to insufficient allowance for thermal expansion. However, after several trials we concluded that the thin tiles simply could not handle the heat.

After much searching, we found refractory tiles for a reasonable price (Southway Refractories www.southway.co.za). They were only slightly thicker than the original tiles and we could replace the inner oven tiles without needing to disturb the front door tiles, which remain secured in place.

Since the tiles in the oven were laid loose, it was relatively easy to replace them - except that this time the chimney and doorway was already built so access was a little tricky!!

Step 13: The Final Product

The next step is perfecting the pizza. We have learned that pizza is about bread, not toppings and that nothing beats a fresh fired focaccia with family and friends.

For more info on building ovens and making pizza www.fornobrava.com is a good resource. Also visit our website for other projects and paraphernalia https://www.thegoodhome.co.za/blog

Feel free to download plans,the Sketchup model and a bill of quantities here.

First Time Author Contest 2018

Runner Up in the
First Time Author Contest 2018

2 People Made This Project!

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27 Comments

This is an awesome Instructable! In case anyone else downloaded the BoQ and was wondering about the currency, I backtracked from the URLs in this instructable to find they were South African, where the currency is the Rand. 1 Rand = $0.079 USD (on 5/3/2018).

Please post your street address and zip code. I'll be right over!

Great job, you’ll have years of fun with that oven. Roasting chickens on vertical rasters is another wonderful use of an masonry oven. you will have no problem baking bread either. Some designs ask for an overkill of thermal mass beacuase it is intended for baking a lot of bread. For your personal use, your design is suitable for bread despite what other commenters have said. Thanks for sharing your project.

1 reply

Those kids have it going on.

Hi,

I had restaurant with a wood burning pizza oven for many
years. Due to the ingrained smell of burning wood and sizzling pizza and,
because it is the only real type of pizza oven, I am forced to read anything on
wood burning ovens. I liked your design, the involvement of the end users in
the construction and the layout of your general Instructable. The oven I had, was build with a much bigger cavity between the outer skin and vault. It was
backfilled with a perlite/vermiculite. Heat retention was great. Could bake a bread the next morning if the oven was used the previous evening and the mouth closed the night before. We used sand to stabilize the inner
roof while building, very much like the Fonobravo design that is doing the rounds but, on your design the formwork and locking bricks works
just as well. For the floor a clay paver bricks worked for me. As I was reading
the Instructable and looking at the pictures I thought to myself that this must
be in South Africa. You gave it away with the Builders Warehouse bag! That was
my favorite store In SA. I am living in China now and the pizzas are terrible! All
electric ovens. I will definitely revisit your Instructable in months to come. Have
to have one of these in my back garden.

Lekker!

Looks great. You would have been better off using bricks for the hearth rather than tiles as this extra thermal mass is useful for getting the pizza base crispy before the top burns. Another addition I would suggest is to either install a well-fitted flue damper or a secondary inner door which sits in past the chimney: While pizzas are cooked with an open door and an active fire, every other type of baking you might like to try involves raking out the coals, sealing the oven and baking / roasting on the stored heat. (see book "THe Bread Builders" for details). You completely correct about not using firebricks / refractory bricks: I've built ten ovens and only one had bricks crack; the one where I used firebricks that happened to be on site

6 replies

I'd agree with everything you said, except that without any insulation and a minimal amount of thermal mass, this oven will probably best suited to pizza, roasting meat/vegetables, etc. Baking break would require a different design, where the heat can be stored in the thermal mass and kept there with insulation. Looks cool either way - enjoy the pizza!

Your point is important but, on closer reading, you will notice that this design includes a layer of the fire resistant insulation "perlite" as insulation (similar to vermiculite in the US?)

You will also notice that there are two (?) layers of brick inside of this insulation layer in the vault - with firebricks over the perlite and river sand on the floor. It seems pretty soundly insulated with some great thermal mass too.

Pity about the lack of flue damper though...

Look closer and you'll realise that thermal mass is actually lacking in the hearth (base of the oven): Over the concrete base is an insulating layer (Vermiculite or perlite can be used but perlite has greater volume for your money. Wear a dust mask when working with either) As any mass outside the insulation doesn't count as thermal mass, you are left with the sand layer and the tiles as TM. Replacing the tiles with solid bricks would probably do the job, particularly if laid on their sides, unmortared. For catering, parties or large families, a much thicker sand bed (~100mm plus) would improve heat storage and therefore cooking time but at the cost of more fuel; so the balance comes down to what you use your oven for. Heat stored in the hearth masonry is vital to getting the base crisp on a pizza before the top burns from radiant heat. The rest of the oven has good thermal mass .

You're spot on about the tiles Scott. I assume Coraliev also realised when replacing the tiled floor with fire bricks, as was described in the text. I think you can see this in one of the photos. I thought perlite and vermiculite were equivalent!? Thanks for the heads-up on that one. I think Coraliev should weigh in on how well her original tiled vs new brick floor retains heat and affects throughput, as this makes for an interesting practical experiment.

Great suggestion - we've been thinking about making a flue damper... watch this space...

I have added drawings with imperial units for the convenience of USA DIY-ers.

Great instructable. You can beat child labour :D. Sorry, family participation.

It's always good being able to give your children practical skills and experience.

1 reply

No dude! You should never beat your child labour!

That's awesome advice when designing furnaces but here we are not trying to "fire" a pizza but rather cook it through quickly. You will find that the main issue is getting the pizza cooked from the bottom before the toppings start to burn. As the author alluded to, it's all about the bread. To achieve a good pizza base the oven floor needs loads of thermal mass to retain enough heat for the throughput of few pizzas before shifting the fire again. The radiant heat from the vault should just balance the heat from the floor to ensure even cooking.

Thermal mass isn't just an efficiency issue: it has a lot to do with the way certain foods should be cooked with bottom heat, heat re-radiated from the roof and the oven's air temperature. Thermal mass is also about heat storage as, apart from pizza, pretty much everything else is best cooked after the fire is removed and the door closed. -mind you, most backyard wood fired ovens almost never get beyond just pizza -because it is incredibly good cooked this way

Oops. I was only looking at the pictures and missed the very helpful pdf diagrams.

Thanks for pointing me the right way in response to my earlier comment, which is oddly no longer visible here.

Hmmmm.... We have an unused corner in the garden that could do with a little improvement like this.....

Great Job!!! Great Instructable!

Do you have a favourite pizza dough recipe that you could share?