different approach to red clay vs firebricks?

[Brewer]

Hey everyone,

Have gone as far to build pedestal with insulating hearth, so I'm ready for some bricks. Firebricks for oven and vent floors = no brainer. I've actually got a few projects going and I'm over budget, so I'm wanting to cut costs where I can. I've read and read and then read some more on clay vs firebricks for the dome. One of my issues is there's very definitive yet non descriptive advice. I don't doubt that firebrick is better, will last longer, less likely to spalling/cracking, etc, but what does this really mean? Am I looking at an oven that lasts 50years instead of 200? Let's say some bricks spall and crack; what is the problem after that happens?

I would like to use firebrick, but I need to make some cuts. While I don't have a full grasp on the difference between what "better" means, I'm willing to accept that it's likely worth the expense. An idea I had was to use red clay brick for the soldier course and perhaps 1 or 2 courses after that. Sure it may spall but it's not going to land on the food. It may crack but it's not where the main heat is getting distributed. So what do you think? Any reason to not do this? While it may seem minimal, $50 here and there makes a huge difference in my overall project budgets. It will likely be the difference between insulating blanket vs only perlcrete for the dome. I haven't come across mixing red clay and firebricks in the dome so thought I get some input.

Thanks in advance!

[TropicalCoasting]

Re: different approach to red clay vs firebricks?

If it was me I would sacrifice the dome blanket and use pearlcrete to afford the fire bricks.
They heat up quicker and dont break down.
They are filthy expensive but Im just going to save up before I start.
Ive tried to get secondhand but living in the middle of nowhere and not having a trailer makes it not even worth considering.


Just add more time to save up or collect the materials you need.

[Brewer]

Re: different approach to red clay vs firebricks?

Thanks for the response tropical. I understand that fire bricks are "better", but will it really matter if I'm just using red clay bricks for the solider course and perhaps second or third course as well? My reasoning is if they spall it won't land in my food and I'd imagine the upper portion of the dome is what gets the most damage from higher temps and thus higher temp swings.

[v12spirit]

Re: different approach to red clay vs firebricks?

Good if you can save money and use firebricks only. But if you are decided to hybridize the build, you would better use firebricks for the hearth and red clay for the entire dome. This is the best compromise as it is recommended by Forno Bravo.

[Brewer]

Re: different approach to red clay vs firebricks?

Thanks v12. I've opted to not do an all red bricks for the dome. Starting to look like going all firebrick is what I'll need to do. Can someone explain the issue though with mixing bricks in the dome?

[Tscarborough]

Re: different approach to red clay vs firebricks?

Differential thermal expansion. "Red clay brick" is equivalent to saying, "car". The red clay brick suitable for building an oven are rare and usually not a lot less expensive than firebrick.

It is hard to determine if your brick are the right kind. Solid, soft brick that are not extruded will generally work.

[Brewer]

Re: different approach to red clay vs firebricks?

Tscar, appreciate the response and thank you for pointing out that my terminology wasn't descriptive enough. Yes, I'm aware of the difference. My plan was to hunt for used bricks off craigslist; found some that I believe will work @ $0.40/brick.

But assuming they're suitable bricks, does my idea in theory make sense? That is, using red bricks for the soldier row and possible 2nd and 3rd. The temperatures wouldn't be as extreme and even if there's spalling or cracking it wouldn't be as detrimental.

[cobblerdave]

Re: different approach to red clay vs firebricks?

G'day
I'd make the hearth floor of firebrick and the dome of the red commons.
A number of reasons. The firebricks are tough and you floor will take a few scrapes over the time. The firebrick being an industrial product are more uniform and are more suitable for a flat even hearth. The hearth bricks are laid loose, no mortar, so if the worst happens and those commons prove unsuitable your firebricks are then reuse able in a rebuild.
Firebricks are not that available in many places. In Australia pressed clay pavers are a choice, in the UK engineering brick is a common choice, both countries tend to want to use firebrick for there hearths if at all possible
Regards
Dave

[Tscarborough]

Re: different approach to red clay vs firebricks?

Firebrick for the floor makes sense from the aspect of conductivity as well. It can be hard to get a balanced cook with common brick (unknown conductivity), while low duty firebrick work great.

[Brewer]

Re: different approach to red clay vs firebricks?

Thanks for the input Dave and tscar

Yes, firebrick for the dome and vent floors were already in my plan. While I still haven't come to a definitive conclusion on what bricks I'll use for the dome, I'm still not sure why a hybrid dome wouldn't work. That is, why would a all red brick dome be preferred to a 3 course red brick and remaining courses firebrick.

[Tscarborough]

Re: different approach to red clay vs firebricks?

I told you, thermal expansion rates are different for firebrick and commons. it will crack at the joint between them.

[Brewer]

Re: different approach to red clay vs firebricks?

My apologies tscar. When you wrote that I thought you were just telling me a difference between the two bricks. Thank you for clarifying the issue with the hybrid dome. All firebrick it is.

[Tractor]

Re: different approach to red clay vs firebricks?

Differential thermal expansion. "Red clay brick" is equivalent to saying, "car".

There's your answer, in theory your oven will tear it's self apart every time it heats up and cools down, as the firebricks and clay bricks will expand and contract at different rates. Just how much damaged will that do and how long will your oven last? I suspect nobody knows because nobody's tried it before.

Only one way to find out I guess

Trac

Edit.... Sorry I didn't read the last two posts before I posted the above. Looks all sorted now

[Brave]

Re: different approach to red clay vs firebricks?

Thanks for the input Dave and tscar

Yes, firebrick for the dome and vent floors were already in my plan. While I still haven't come to a definitive conclusion on what bricks I'll use for the dome, I'm still not sure why a hybrid dome wouldn't work. That is, why would a all red brick dome be preferred to a 3 course red brick and remaining courses firebrick.

Hiya. This is my first post but I've been researching for a while. I was originally thinking that I would go with a fire brick hearth and a red brick dome but have changed from that position. Having different types of bricks in the one area would have issues I'd imagine. They'd expand at different rates and would probably heat up / radiate / cool down differently too. And it'd look weird. I've been getting a bit of info here. How to build a pizza oven