In this instructable we will describe how to build a real Portuguese brick pizza oven.
Portuguese ovens are characterized by higher dome than the Italian / Neapolitan ovens. What this means in practice is less intense heat. In all of these ovens the heat is reflected from the dome back onto the cooking floor and the lower the dome the higher the heat. While the Italian pizza ovens are made primarily for pizza (they cook other foods too, but most people buy them for pizza) the Portuguese ovens are made with cooking a variety of foods in mind: slow roasts, lasagnas, bread etc. For all of these you will need less heat than for pizza and hence a Portguese ovens can come in handy. Now, this does not mean that it won't cook pizza - it absolutely will! But maintaining 900-1100F heat is easier in quality Neapolitan oven than a Portuguese one.
The video posted on this page shows the entire process (it's a combination of static shots and video). we describe the process in more detail and with relevant pictures in the following steps.
Portugal has centuries-old oven building traditions. Drive around and you will see. Wood fired ovens and charcoal grills are sold along major highways like ice cream in America, it's pretty amazing.
Up next: the Portuguese clay oven.
Before we jump to the main topic - the brick oven - it's worthwhile to point out that Portugal has another kind of oven which works the same way but is built from terracotta clay. It's called "Pereruela" style after a Spanish city where this style of oven is popular - and maybe even originated. The video on this page describes it all. Basically clay os rolled by hand until the oven shell is completed. Once this is done the oven (dozens of them actually) is heated in a huge kiln - also wood fired - and then afterwards insulation, cement, tiles, door, and other things are added to make the oven complete. We have attached some pictures on this page.
The result is a great oven with a beautiful interior - one piece terracotta. However for most people this is not a DIY home project. Rolling clay this way takes experience and hence we decided to concentrate on the brick oven - which is a common DIY build.
There are a few things about the Portuguese brick oven which are different than a traditional DIY firebrick oven in USA.
1) the bricks used are clay. yes, regular clay bricks - they will hold up to the high Ts even though they will have small cracks - this is normal. Clay brick are very cheap in USA, the last i saw was about 80 cents per brick and i'm sure there are places that sell for less.
2) ideally the bricks should be rounded. these are widely available in Portugal, not so widely in US but importers are started to bring them in and in general i believe they are possible to come buy. if you don't have rounded bricks then the straight ones will do.
3) as the dome is higher than a Neapolitan oven. In a Neapolitan brick oven the inside heights of the dome is 16"-18". In the Portuguese it should be 25" in the middle.
Up next: the base.
Like all things a good brick oven will require a good foundation. The foundation is made from cement, reinforced with steel bars. We like to keep the corners rounded as opposed to straight because straight corners can easily suffer damage when you move your oven - they can break off. You will need to make a mould for your base - most likely from 1x3 timber. This is just the frame - 4 sides. You don't really need a floor for your mould as long as you construct it on something flat and solid and to which cement will not stick. If you are doing this in your garage on concrete floor this is great, but make sure to cover your floor with a few layers of plastic to make sure the oven does not stick to the floor. To make corners rounded insert anything that will provide this shape on the 4 corners - this can be just a few bricks if you have a grinder and can create this semicircle shape, or... used cans! You will need to cut them in the middle to get the right shape, this way each can can provide for 2 corners.
You can pour a 2" layer of Portland cement, wait 1 day for it to harden a little and then we need to place the metal bars before pouring more cement. Very important: since eventually you will want to lift your oven you need to leave lifting eyes exposed, 1 on each corner. In order for these lifting eyes to function the whole structure of rebars inside the base of the oven has to be interconnected - otherwise you stand the risk of the lifting eye being ripped out when you try to lift the oven. Hence there is some welding involved in this stage unless you can get them already welded together - a frame... Once you have joined the rebars together you will need to add a lifting eye on each corner. You can use regular lifting shackles from a hardware store, this should save you some welding, just make sure they are large enough to let a hook inside even after you pour the additional 1" layer of cement.
Pour the remaining 1" layer, make sure the lifting eyes are pointing straight up to allow hooks to be inserted later.
Once the cement has hardened (at least 4-5 days) you can remove your timber frame. Lay out the first layer of clay brick as shown here. Add a layer of sand inside and then mineral wool - at east 2". Better ceramic fiber and even better rigid mineral board but the last 2 items are not available from Home Depot and are a little costly while mineral wool is sold by Home Depot and is cheaper.
This is not yet your cooking surface! Cover the whole thing with cement. Once it hardens spray a layer of sand on top of this new raised surface. Now, the next layer will be the actual cooking floor. Here you have options. In Portugal what they use the most is terracotta tiles. In the States it's firebrick. Firebricks are available in 12x12x1 size which would be great in this case. You will certainly need to cut the tiles or the bricks to make everything fit.If the surface is not 100% level use sand under the floor to level it out.
Next: the dome.
This is the main part. Making a non-fragmented perfectly spherical dome is tricky. And to make matters worse there are no common tools which allow to keep the dome spherical. This is where the rounded bricks come in - if you have access to them they will make the job easier.
Please disregard the arch for now, we will concentrate on this in next step.
When you build the dome go clockwise. Don't jump from one spot to another skipping a brick in between! This is the best way to ensure a uniform dome.
Now, the cement you should use here is not Portland - this should be refractory cement.
Don't forget to wipe off extra cement all the time - especially from the inside of the oven, otherwise it will harden there and will be a lot more difficult to remove once the dome is complete.
If you have watches the video you probably saw that after each layer of the dome is completed there is a wire place on top of it. This is a great practice to reinforce the dome.
If you are using bricks with holes in the middle (as the ones in our pictures) fill up the holes with cement.
Up next: the arch.
Your oven will need to have a chimney. To add the chimney you will need a structure in front of the oven - called "the landing area" - basically the arch. Pizza oven kits usually already come with one but if you are building an oven from scratch you will need to build this too. Basically this means making a brick stack in front of the door opening of the oven. Later we will add a chimney to the top of the arch - you can leave the arch unfinished in the middle (3 bricks missing) and later use this area for the chimney.
Basically the arch is just a stack of bricks. You can build it on the floor - horizontally - and then just lift it and cement it to the oven, this is easier.
Next: finishing the dome.
The brick work of your dome is not complete but this isn't the complete oven yet. The dome still has to be insulated, reinforced, and covered.
Firstly you will need to cover the dome with chicken wire. Then a half inch layer of refractory cement.. Now the main part: insulation. The best insulation out there is ceramic fiber blankets (Kaowool, Superwoold etc). You are using them use a 6 or 8 lb density. You will need a 3" layer all around the dome. This usually means 3 x 1" layers as they normally come in 1" thickness.
Mineral wool will also insulate, if you are using it use 3"-5".
Once the insulation is applied use another layer of chicken wire to hold it together. The final layer of refractory cement goes on top of the chicken wire.
Wait for everything to harden - a few days. And then you can paint it with latex concrete paint.
Up next: the chimney.
We are now back to the arch which we basically left unfinished waiting for its chimney.
If your oven is going outdoor then you can use a clay pipe, it's widely available and usually costs $10-15 depending on the length. You can use a 12" high chimney, it will do just fine. Of course you can also use stainless steel chimney or black stove pipe. You can use fireplace mortar to attach the chimney to the oven. If you are using a stainless steel pipe you might as well use the matching anchor plate. In this case you can just twist lock your chimney to the anchor plate.
The most common chimney diameter for an oven with under a 40" cooking area diameter is 6". Large than this you may want to go with 8".
Next: applying veneer, making your oven beautiful!
Functionally your oven is finished - but what about the looks? Sky is the limit when it comes to this, you can cover your oven with tiles, stones, bricks, stucco, or even completely enclose it. Depending on the scope of your project (and budget) help from a professional stone mason may be required at this point.
We have added some pictures here of the custom installs of our Portuguese ovens.
Next stage would be curing the oven and beginning to cook crusty pizzas and mouth watering bread. Once day we will try to make an Instructable about this, many thanks for reading this one!