Got these firebricks, how should I build a pizza oven with them?

[Fizz]

Hello everybody!

I got these bricks from a friend who´s had them stacked outside for problably a decade or more.. They look pretty worn and torn, but feel solid ..

There are 63 curved ones, 26 medium sized ones (somewhat larger then a regular brick) and 10 larger ones (the whiter ones in the first pic). I also got 12 lighter ones, that I think are isulating firebricks..

I layed them out on the garage floor, and created the footprint (second pic), and decided to go with a barrel design with 4 and a half curved brick to create the roof ...

Any input would be highly appreciated!

[Gulf]

Fizz,

Welcome to the forum! That is an interesting shape for fire brick. A barrel vault seems to be the best choice. From the stamp in the pic I would have guessed that they were an ultrahigh 65% alumina. However, I did a quick search of those markings and found Höganäs Bjuf Refractories. A click on their products, link to a page shows a BJUF.SX (line 4) as a 35% alumina alkali resistant firebrick. So, I'm guessing that the "36.27" stamp is the actual alumina content (much easier to cut with a wet saw than 65%). From reading their page they have been in the business for a long time. You may be able to contact them with some questions. Aside from all that, clean and dry them real good so that the mortar will stick, and have fun .

[Fizz]

Fizz,

Welcome to the forum! That is an interesting shape for fire brick. A barrel vault seems to be the best choice. From the stamp in the pic I would have guessed that they were an ultrahigh 65% alumina. However, I did a quick search of those markings and found Höganäs Bjuf Refractories. A click on their products, link to a page shows a BJUF.SX (line 4) as a 35% alumina alkali resistant firebrick. So, I'm guessing that the "36.27" stamp is the actual alumina content (much easier to cut with a wet saw than 65%). From reading their page they have been in the business for a long time. You may be able to contact them with some questions. Aside from all that, clean and dry them real good so that the mortar will stick, and have fun .

Thanks for the reply! (and the behind the scenes work I suppose one of you moderators did to delete my double posts )

The dome will be about 12-13 inches high, and the base will be about 23 x 35 inches, what do you experienced builders think about that?
I´ve been reading some threads here, and it seams that 12 inches is a pretty low dome, if I use 5 full curved stones I´ll get a little over 15 inches height, is that better?
I´ll use the oven mostly for pizza, so a low oven will heat up faster, which is better I guess?

The bricks were pretty easy to cut, at least compared to the concrete/granite I´m used to working with ...

[UtahBeehiver]

If you use full 5 curve segments will it increase the width? 23" wide is on the small side as you move the coals/fire to one side for cooking. 15" in height is not too high. The key is good floor and dome insulation for a good preforming oven. Refer to Tscarborough's build, it was a very nice barrel build. https://community.fornobravo.com/mem...8-tscarborough

[Fizz]

If you use full 5 curve segments will it increase the width? 23" wide is on the small side as you move the coals/fire to one side for cooking. 15" in height is not too high. The key is good floor and dome insulation for a good preforming oven. Refer to Tscarborough's build, it was a very nice barrel build. https://community.fornobravo.com/mem...8-tscarborough

Thanks for the reply!

The width won´t change much, I´ll get slightly more than a half circle, so maybe somewhat smaller ...

My plan was to push the fire inwards, but maybe it´s better to aim for a square design rather than rectangular?

I could´nt find Tscarboroughs build, maybe it´s my search skills, maybe i´ts the forum ..

[dakzaag]

Ts is a master oven operator, builder and works in the masonry industry. Look him up and study. You can build up side walls with square brick and set the arch on top of the side walls to get more height. You can also stair step (corbel) the side walls a bit to gain clearance and then cut the top brick with a skew angle to accept the curved arch brick. All this could gain you 5" of width or more depending on how elaborate you want to be. The arch brick are not very thick, so the oven will heat quickly and then cool quickly compared to other heavier ovens. Great for piazza, challenging for bread. I think you have about half the brick needed, maybe less to complete this oven, and a little planning could result in a really unique build.

[UtahBeehiver]

Here is Tscar's build link.
https://community.fornobravo.com/for...71-it-is-begun

[Fizz]

UtahBeehiver thanks for the link! Truly impressive work from him...

@dakzaak studied his build thread, and got some really good input... Offsetting the vault from the opening seems to be a good way to utilize a smaller vault...

I was thinking of using some old regular bricks I have lying around to add mass to the oven... The curved bricks are two inches thick...

[dakzaag]

Nothing wrong with using common brick for mass, use refractory mortar since the temp will go up, although I doubt you will get over 550 F in the mass of the oven. Better to be safe. If you corbel the walls, think about cutting the projection of the brick off before you lay it and then the inside of the oven will look intentionally smooth.

[Fizz]

Nothing wrong with using common brick for mass, use refractory mortar since the temp will go up, although I doubt you will get over 550 F in the mass of the oven. Better to be safe. If you corbel the walls, think about cutting the projection of the brick off before you lay it and then the inside of the oven will look intentionally smooth.

Thanks for the input!

I´ve been reading about keeping the mortar btw the bricks to a minimum, and if I´m meticulous when cutting the curved bricks, I could probably assemble the entire vault without using any mortar between the bricks.. Is there any advantage in that? I guess I´d had to cover it in mortar and then add the second layer of bricks, would that be as strong?

[deejayoh]

I dont' know that there is any real advantage to building an oven with no mortar. It's more of a dream some builders have.

Check how the italians do it... https://youtu.be/sM9zteuE8UA

This is the oven that is in every pizzeria in Naples

[Fizz]

I dont' know that there is any real advantage to building an oven with no mortar. It's more of a dream some builders have.

Check how the italians do it... https://youtu.be/sM9zteuE8UA

This is the oven that is in every pizzeria in Naples

I think I´ve watched every video available at Youtube (about oven building), except that one ..

Interesting use of metal in the oven, I guess the ring around the dome is pretty good when making the oven in two pieces, but I wonder how they make the door/opening work ..

I noticed that they used LECA to isolate the oven, that answered one of my questions, since vermiculite is somewhat hard to get by here in Sweden .. Precast LECA blocks are a staple when building walls etc. here in northern Europe!

[dakzaag]

As far as not using mortar, this is more theoretical than practical. Refractory cement is designed for 1/8 inch joints or less. This cement helps fill in normal gaps that imperfect brick will have when laid together. It also has some glue factor as construction reaches higher up on the dome and the brick want to slide off the chain because of gravity. Refractory cement sets up during the curing fires and really bonds the brick together so you have a very stable unit. You mention curved cuts and this is another challenge as the blades we use are straight. You can't really cut a curve unless it is so gradual as to no be noticeable. You can grind a curve out, but this is challenging as well to get it perfect. Mortar is your friend, not the enemy.

When building a round structure with square brick, you have big joints in certain places and Refractory cement is not appropriate in these places. Refractory mortar can be used to fill in wider joints up to and even exceeding an inch in width. If you use square brick to build a sphere or dome, you will have some joints approaching 1 inch on the outside of the dome. Refractory mortar is different then refractory cement in that it has sand in the mix to give the mortar more substance to fill bigger gaps. It is still temperature stable and very handy when you get tired of making the perfect cut and realize that you are the only one who will ever see the joints on the inner arch where it meets the the wall chains.

[Fizz]

As far as not using mortar, this is more theoretical than practical. Refractory cement is designed for 1/8 inch joints or less. This cement helps fill in normal gaps that imperfect brick will have when laid together. It also has some glue factor as construction reaches higher up on the dome and the brick want to slide off the chain because of gravity. Refractory cement sets up during the curing fires and really bonds the brick together so you have a very stable unit. You mention curved cuts and this is another challenge as the blades we use are straight. You can't really cut a curve unless it is so gradual as to no be noticeable. You can grind a curve out, but this is challenging as well to get it perfect. Mortar is your friend, not the enemy.

When building a round structure with square brick, you have big joints in certain places and Refractory cement is not appropriate in these places. Refractory mortar can be used to fill in wider joints up to and even exceeding an inch in width. If you use square brick to build a sphere or dome, you will have some joints approaching 1 inch on the outside of the dome. Refractory mortar is different then refractory cement in that it has sand in the mix to give the mortar more substance to fill bigger gaps. It is still temperature stable and very handy when you get tired of making the perfect cut and realize that you are the only one who will ever see the joints on the inner arch where it meets the the wall chains.

Thanks for the input!

It´s winter here in Sweden, which means temperature ranges btw -4 to 40 F .... I´m thinking about starting to make separate arches indoors, to speed up the process when I start building the oven .. Making one "wood template" and using refractory cement to join 4 and a half curved brick to make 8-9 arches instead of building the entire vault on top of a larger template should save me some time ...

Do you think it´s a good idea?

[UtahBeehiver]

It would be best to stagger the bond on the arch for strength and integrity. By pre-making the arches there will be a long seam at each joint of the pre-made arch unless I am not understanding what you are trying to do.