Hey Folks!

[justsan]

Hello,

I've been trolling this forum for some time and about 2 months ago started my build! I'm in San Diego and have a couple of questions about Hearth insulation.

Everyone says 2" min but 4" is better...I poured a standard countertop which turned out to be a little over 3" of 6500 PSI concrete.
I purchased the FB Insulation board from forno bravo and it states that it's "...more efficient than vermiculite by a factor of 2 to 1",
so I figured that 2" of the FB board would be fine, but I am 2nd guessing that - will I be ok with building my 44" oven on top of just the 2" FM Board?


Another question - some people put their first row of soldiers on top of the firebrick floor, but some folks put their first row of soldiers on top of the FB Board - which is a better approach and why?

Thanks so much - I've already learned a ton from this Forum!

[Drew Van Niekerk]

We are building a new home and want to construct a side-by-side fireplace pizza oven combination in our kitchen. We want to have two connected internal chambers and two external doors. Any thoughts on feasibility? Plans?

[RandyJ]

I think you would be better off doing it as 2 separate pices. You will compromise the cooking abilities of the oven severely by having it open in side. You want and need to be a sealed chamber that is well insulated. Then you can use it to bake and roast with retained heat. Also it makes it easier to cook pizzas. You could have them next to each other but do not connect them. They will both be compromised.

Randy

[Drew Van Niekerk]

That's great, I suspected this wasn't going to be easy. Our fireplace opens into the kitchen and has a sealed glass door facing the dining room. The fireplace divides the rooms. I wanted to keep it to one fire surface and have the fire at the mouth of the oven which I thought could be elevated and smaller than the main chamber and have a curved, low ceiling. I realize we'd need to only use the pizza oven door only when cooking and it may not heat up enough. We would consider adding a gas fed heat source additionally. The fireplace will already be fit for gas regardless.

Do you think it would work or still no?

[Drew Van Niekerk]

Some sketches. Thanks for your help.

[Drew Van Niekerk]

We were also thinking about having an internal door in the pizza oven that closes off to the main fire so that it could be gas heated then open to fire and close off gas to continue with wood fire cooking. Are we pushing for something that is to complicated to resolve?

[RandyJ]

There are scientific reasons why this is not a good idea. You need to have a certain ratio of dome height to door height to get proper combination. Also it affects how say a pizza will cook. It has a lot to do with radiant heat. I believe fireplaces also have certain rules that alow them to properly operate. You could end up with a situation where both sides function poorly. A door in the middle also won't be a viable option unless it was extremely solid and heavy-duty and then you would not be able to open or close while operating. It will be easier and less work to build 2 separate units and then they will both function properly. If space is limited then you could use the oven as a fireplace. They produce a lot of heat. I did steaks in mine the other day and would guess the temp at around 1300F that was 2 min a side. If done right they are very useful.

Randy

[admin]

Hi Drew,

I am going to move your topic into the Newbie forum where I think you will get more response from the Forum community.

Randy, please look in the Newbie forum for this topic.

Mitch

[RandyJ]

It all depends on what you can reasonably afford. I did 4 " and am very happy. But if money is a issue it can be done as 2" and still function well. It just won't hold heat as long.

Randy

[UtahBeehiver]

Justan,

Welcome to the journey. To answer your questions, 2" will suffice, it is the minimum floor insulation. More insulation, up to a point will improve the heat retention of the oven. So it is a matter of budget and what and how you want to use your oven. If you plan on cooking pizza and maybe a roast or so the next day then 2" should be fine. If you want 4-5 days of cooking heat then more insulation would be in order. Up to you.

You mention a 3" slab for a 44" oven. These beast are heavy and a little late now but the concrete needs good rebar or good support underneath, You did not mention what you did here.

First course outside on CaSi board or on firebrick. Either one works fine. Just to be sure, the first row does not necessarily need to be soldiers, can be 1/2 headers and would be if you are doing a hemisphere dome. Some members say having the first row outside the floor will allow the ability to replace a brick anyplace on the floor (but over the years I have this happen very often). Placing the first course on the floor could save you having to do precision circular floor cuts and especially if you enclose the oven vs an igloo you can rough cut or leave long the floor brick since covered up once enclosed.

[justsan]

Welcome to the journey. To answer your questions, 2" will suffice, it is the minimum floor insulation. More insulation, up to a point will improve the heat retention of the oven. So it is a matter of budget and what and how you want to use your oven. If you plan on cooking pizza and maybe a roast or so the next day then 2" should be fine. If you want 4-5 days of cooking heat then more insulation would be in order. Up to you.

It all depends on what you can reasonably afford. I did 4 " and am very happy. But if money is a issue it can be done as 2" and still function well. It just won't hold heat as long.

Randy

Thanks for your help fellas. Money isn't an issue, but I only bought enough FB Board for 2" and I want to get this project rolling this weekend, lol. Not sure if i'll cook for 3-5 days after a fire, but I sure would be bummed if I wanted to and couldn't.

You mention a 3" slab for a 44" oven. These beast are heavy and a little late now but the concrete needs good rebar or good support underneath, You did not mention what you did here.

Yeah, I was a little worried about this. I was going to go with a standard 42" Pompeii but I had room to make my slab larger so I did, but I only ended up with a 3.1" top. It's stuffed with 1x1 3/8th's rebar, and I used 6500 PSI concrete so it should be pretty strong. I'm not a builder by any means, i've dealt with concrete a lot, but this is my first time even using a tile saw. I did not put any additional supports on the interior of the counter top and am probably going to regret that. I still have the form on the interior I have not removed yet, I'm kinda thinking of just keeping it and maybe making brick pillars around the supporting 2X4's - if you have any suggestions about adding additional support I would love to hear them.

I like the idea of making my first row on the exterior of the firebrick floor, I don't mind the extra cutting.

Thank you!

Justin

[JRPizza]

Justin, welcome to the forum. What a beautiful view you have from your oven location - looking forward to seeing your progress.

[justsan]

Justin, welcome to the forum. What a beautiful view you have from your oven location - looking forward to seeing your progress.

Thanks JR Pizza. Maybe i'll have to start a build thread.

You have any input on my counter top support query?

[UtahBeehiver]

Cutting of the floor will keep you busy for a day or so. Since you budget can stand a little more insulation then go get some. I notice you are near San Diego, so EJ Bartell aka Distribution International carries ThemoGold 12 CaSi in all thickness and there is a store in San Diego (I am sure there are other refractory product distributors as well). Now is the time to consider more, Once you lay the brick floor down you cannot add more.

[JRPizza]

Unfortunately nothing concrete (pun intended). There are others on the forum smarter on concrete structure, so hopefully they will weigh in. Do you have any pics of your foundation and forms pre-pour you could share? They might be helpful. You said 1X1 3/8 rebar - do you mean a heavy mesh of 3/8 wire? Might make a difference to experts. I do know that the ovens carry their weight around the periphery, so you might want to consider internal support where the oven foot print is going to sit on unsupported slab. I made my slab a little over 4" and used plenty of stout rebar as I didn't know what I needed so wanted to overkill it.