Hello from the Philippines

[raechelle]

Hi, my name is Raechelle! My husband and I are building our first brick oven. We have started with the foundation, tomorrow we'll be checking out one supplier of refractory bricks and mortar cement. Finding the yellow type of firebrick is quite hard here so the prices are also expensive. We mostly have the red clay bricks, but read somewhere that if we are planning to go for very high heat, we should be using the same bricks used in kilns.

Looking forward to learning more from the experts here on how to build a proper and safe brick oven. Thanks!

[UtahBeehiver]

Have you downloaded the free eplans from Forno Bravo, it is a good baseline for oven design and construction a little dated but a good place to start. There have been a few builds from the Phillipines, one quite large. Do a search of the forum. Fire bricks come in many colors, yellow most common but red is also out there but red clay and red colored refractory bricks are not the same. You may want to consider a cast refractory dome with a fire brick floor if you are budget constrained. Look at post from David S, he is our cast expert.

[raechelle]

Have you downloaded the free eplans from Forno Bravo, it is a good baseline for oven design and construction a little dated but a good place to start. There have been a few builds from the Phillipines, one quite large. Do a search of the forum. Fire bricks come in many colors, yellow most common but red is also out there but red clay and red colored refractory bricks are not the same. You may want to consider a cast refractory dome with a fire brick floor if you are budget constrained. Look at post from David S, he is our cast expert.

Thank you for the reference! I'll definitely check on the ovens built here, honestly quite relieved to see some fellow countrymen. Would be easier to check for pointers especially with the type of climate here. I just stopped my husband from buying 60 kgs of salt as one of the members here just confirmed my suspicion that humidity will just get the salt mushy.

We actually just met the guy who's selling the refractory bricks and told him of our plan: build the oven floor with the said bricks and the dome with the red clay bricks fortifying it with a 4-inch castable.

Will be posting the progress here soon. Crossing everything that can be crossed that it won't be a fail!

[JRPizza]

You are going to put 4" of castable over a red clay brick dome? First off that seems like a very large thermal mass to have to heat, as most brick domes are about 4.5" thick and most cast ones are I believe 2 to 4 inches thick. Second if you plan on keeping the oven for years to come, and plan on lots of fires, you might want to reconsider using the red bricks. I hear they will work in a pinch but many builders report spalling after a few years of use. You might be way better off just using the castable both for obtaining a more common thermal mass(thickness) and to have a more durable dome (no brick fragments falling into your food).

[UtahBeehiver]

Here is a link to Lacer's build, it is really big but his thread may give you some material sources. He has not been active for quite a while though.

https://community.fornobravo.com/for...stralia-anyhoo

[raechelle]

Hey peeps, just a follow up. We are halfway through our build, mostly orchestrated by my husband. I’m so confused on the type of build they have made but it looks like it’s going well. Okay, just to summarize the oven components:

1) oven floor is
inner: 30%cement 70% pumice
actual oven flooring: refractory bricks and wet mortar

2) dome:

Side base is refractory bricks with castable
Upper bricks: red bricks with castable
Inside dome layer: 3” castable Brand:BST 13ES
middle dome layer: 1” castable Brand: BST 13LW
Outer dome layer: 1” red clay bricks with 13ES castable

crossing my fingers that this build will require minimal fixes

[david s]

How thick is your pumice insulation mix under the cooking floor and how thick are the cooking floor bricks? Generally the thickness of the cooking floor bricks is about the same as the thickness of the dome walls.
Do you have any insulation over the dome?

[raechelle]

How thick is your pumice insulation mix under the cooking floor and how thick are the cooking floor bricks? Generally the thickness of the cooking floor bricks is about the same as the thickness of the dome walls.
Do you have any insulation over the dome?

pumice insulation mix - 3 inches + 1-2 inches of wet mortar and castable on top

cooking floor - is 2.5 refractory bricks binded by wet mortar and castable

ok, now I got more clarification about the dome. So here are the layers

innermost dome: 13ES castable around 2 inches thick
Middle layer dome: 13Light weight castable around 1-2 inches think
outer layer: 2 inches red brick
outermost layer: will be covered by another 1/2 upto inch layer of lightweight castable

Did what I write made sense or not?

my husband decided not to put an insulating blanket as the light weight castable is the substitute for that.

I’m crossing everything that can be crossed in my body that this will work and not just crumble right before our eyes!

[raechelle]

[david s]

Hi Raechelle,

Here is a rough drawing from the interpretation of your explanation.(correct me if I'm wrong)
Firstly your underfloor insulation with your 70% pumice 30% cement equates to a 2.5:1 vermiculite:cement mix. The pumice is approximately (slightly denser than vermiculite) the same as vermiculite (see table for resulting insulation values. Most builders would use a 4" of 5:1 vermicrete to achieve good insulation with enough strength to support the weight on top of it. So it appears you probably don't have enough insulation under the floor, 2.5:1 is about 1/2 as insulating as a 5:1 mix, and you only have 3" of it, but don't worry, it will work.

2.5" firebrick sitting on 1-2" dense castable and mortar gives you a pretty thick dense thermal mass for the floor.

2" of dense castable for the inner dome is standard and provides sufficient thermal mass as well as the required strength.

1-2" of lightweight castable is very minimal insulation for the dome, most builders would use around 4" of over the dome insulation. Not sure of the insulating value of your insulating castable (you could check that against that of insulating blanket.

The 2" red brick layer is not an insulator, but a conductor, insulating over it will help hold in its heat once the bricks have heated up.

It appears that you have a 4" x 4' (16 square inches) for your flue. Not knowing what the internal size of your oven is, it is hard to say if it's adequate, but ovens up to 28" internal diameter require a 5" diameter round flue pipe (20 square inches), up to 36" internal diameter ovens require a 6" diameter flue pipe (28 sq inches) and ovens over 36 internal diameter 8" pipe (50 sq inches)
The chimney can be brick, but if you use a pipe, make sure it's stainless or you'll have to replace it after several years use.

Dave

[raechelle]

Hi Raechelle,

Here is a rough drawing from the interpretation of your explanation.(correct me if I'm wrong)
Firstly your underfloor insulation with your 70% pumice 30% cement equates to a 2.5:1 vermiculite:cement mix. The pumice is approximately (slightly denser than vermiculite) the same as vermiculite (see table for resulting insulation values. Most builders would use a 4" of 5:1 vermicrete to achieve good insulation with enough strength to support the weight on top of it. So it appears you probably don't have enough insulation under the floor, 2.5:1 is about 1/2 as insulating as a 5:1 mix, and you only have 3" of it, but don't worry, it will work.

2.5" firebrick sitting on 1-2" dense castable and mortar gives you a pretty thick dense thermal mass for the floor.

2" of dense castable for the inner dome is standard and provides sufficient thermal mass as well as the required strength.

1-2" of lightweight castable is very minimal insulation for the dome, most builders would use around 4" of over the dome insulation. Not sure of the insulating value of your insulating castable (you could check that against that of insulating blanket.

The 2" red brick layer is not an insulator, but a conductor, insulating over it will help hold in its heat once the bricks have heated up.

It appears that you have a 4" x 4' (16 square inches) for your flue. Not knowing what the internal size of your oven is, it is hard to say if it's adequate, but ovens up to 28" internal diameter require a 5" diameter round flue pipe (20 square inches), up to 36" internal diameter ovens require a 6" diameter flue pipe (28 sq inches) and ovens over 36 internal diameter 8" pipe (50 sq inches)
The chimney can be brick, but if you use a pipe, make sure it's stainless or you'll have to replace it after several years use.

Dave

Wow, it’s so amazing that you were able to draw it accurately!
and yes, the flue is about 50-52 sq inches.