New Build

[thevance53@gmail.com]

Hello from Utah. I just got my suspended slab poured and looking to start my rectangular dog house style oven. I wanted a little bigger oven so I was thinking 63"x 54", but I haven't seen anything quite that big. These are my questions:
1) Is there a a dome height ration that is too flat? I was thinking 10" - 14", but with a wider oven worry about the bricks falling?
2) I have a 5-1/2" reinforced concrete slab poured over metal deck. Do I need to put any fireclay mortar under or between the bricks on the floor of the oven?
3) What is the best, but cheapest mortar formula for the firebrick?
3) Is the chimney built into the top dome, or does it just sit on top and is attached only with mortar?

I was going to upload what I was basing my oven design on, but it said it was an invalid file? I appreciate any and all help.

Mike

[UtahBeehiver]

Welcome to the forum.

Where in Utah? I am in SLC.

First, I am making the assumption you want to build a barrel type oven. What is the purpose of this oven? This is a really big oven and there are not too many barrel builds but a few. Big is not always better. So depending on how you want to use the oven could affect the size. Bigger ovens mean more fuel. Most of us only cook 2-3 pizzas at a time.

1. Look at Tscar's build, it is a barrel oven. I am going to defer to the barrel builders but the flatter the roof the more need for supporting the side walls and additional reinforcement.
2. Fireclay/sand mix is merely for leveling purposes. I am assuming there is insulation under the fire brick and above your concrete hearth slab.
3. Homebrew has been commonly used on the Forum builds, the general formula is 3-1-1-1 (sand, lime, fireclay, portland) but there are slightly different versions out there.
4. Defer to the barrel people

Posts are restricted until approved which I just did. It may solve your pic problem or the pic is too big or in a format the won't work. Generally, jpgs, pdfs, zips, xls work

[thevance53@gmail.com]

Thanks. I am in Riverton. It is a barrel type I have just laid it out on my slab and it is way too big. I am going to stay large, since my slab is so big, but I will kick it down to outside dimensions of 54" x 45". The main purpose is pizzas, but with such a large oven, I would think I could could a variety of things near the front at lower temps.

I was planning on getting most of my materials from Beuhner. Is that a reasonable approach? I checked fro fire brick on KSL and Craigs list, but didn't come up with anything.



Not sure if this worked, but I saved the pdf to a single page and tried to attach.

[UtahBeehiver]

The PDF show up now, fairly high internal arch and I could not tell from the one shot how it was floor and the barrel is insulated. This is critical for a good performing oven and the whole oven needs to be isolated from any contact with the base or concrete hearth. Here is the link to Tscar's barrel build and maybe it will give you some design ideas. I did notice there is no reveal on the oven opening which makes it harder to seal for "after" pizza cooking.

https://community.fornobravo.com/for...71-it-is-begun

Here are a few sources of materials in SLC

EJ Bartells - ceramic fiber blanket and board - fire brick but I did not buy here, used surplus brick from KSL
Sutherlands - quartz sand
Interstate Brick - fire clay - fire brick but I did not buy here
Beuhner - Perlite


Good luck.

[thevance53@gmail.com]

Perfect. Yea, I will insulate the floor and the walls and finish with the stucco. Is vermiculite (flooks like smallfoam pebbles) the same as perlite? The biggest question is the chimney. Should I have it on the main barrel vault, or extend the lower vault and have it there? Tscar's project was an awsome build. Thanks for all the help.

[UtahBeehiver]

Send Tscar a private message and ask him. I did an igloo so I can't answer your question. Both are similar. As far as insulation p or vcrete are about 1/2 as effective as ceramic board. IE 2" of ceramic board or blanket requires 4" of p or v crete. 5 or 6 to 1 on floor is a good baseline could go up to 8 to 1 on dome but a little more crumbly. Do a search under David S, he has a table showing insulation values of p/v crete.

[david s]

I use 5:1 vermicrete for under floor insulation because you need some strength there. That is about half as good as insulating blanket, so to achieve the same insulating value you need to double the thickness. For over the dome I use 10:1 because you don't need strength there, only just firm enough to render over. Any leaner than 10:1, I find difficult to apply. A 10:1 brew is about as good as blanket. If you are doing an enclosure you can pour vermiculite or perlite (they are interchangeable) in loose and it's as good an insulator as blanket.
See table attached.

[thevance53@gmail.com]

If I use the 4" vermicrete method, do I need to lay a fireclay/sand bed over the vermicrete or just lay the fire brick directly over the vermicrete?

[UtahBeehiver]

Depends on how level your vcrete turns out. The 50/50 sand-fireclay mix is for leveling purposes only. A 4" 5 to 1 vcrete or pcrete is the bare min. insulation on the floor which is roughly equal to 2" of CF board. You need to consider increasing the thickness to at least 6" or 8".

[danjmath]

I grew up in Riverton, and am in the process of building mine down in Lehi. GL with it.

I can't give as good of an answer as UtahBehiver, but I personally am doing 3" of p-crete, then 2 or 3 inches of CaSi Board(I don't remeber the thickness exactly, I am picking it up this week) that I am buying from EJ Bartell's up in Salt Lake.

The CaSi board is going to cost me ~$70, but I only have a 36" dome. I think its $12 for a (2or3)x12"x24". If you do go for the CaSi board, at least you might not have to cut it for a rectangular base. I hear that part is nasty.

[RandyJ]

You would be well advised to do a layer of cf board on top of the vermicreete. You will have much better heat retention and better heat up .

Randy

[thevance53@gmail.com]

Awesome, right around the corner. Sounds like we may be around the same point in the build. Maybe we can trade services to get them both done a little quicker? Mix p-crete? I have a couple bags of extra Perilite from work if your interested. What is the current height of your base? With the p-crete, CaSi board, and then the fire brick, i will be about 8 or 9" above my hearth slab. This may be getting pretty high and I was kind of wanting to use that as a staging or prep area. Have you got your firebrick yet? I have attached a picture of my base to show where I am at and get any critiques (the slab is level but the perspective was off). Thanks for any help.

[deejayoh]

Thanks. I am in Riverton. It is a barrel type I have just laid it out on my slab and it is way too big. I am going to stay large, since my slab is so big, but I will kick it down to outside dimensions of 54" x 45". The main purpose is pizzas, but with such a large oven, I would think I could could a variety of things near the front at lower temps.

I was planning on getting most of my materials from Beuhner. Is that a reasonable approach? I checked fro fire brick on KSL and Craigs list, but didn't come up with anything.

[ATTACH=CONFIG]temp_77358_1467497160190_384[/ATTACH]

Not sure if this worked, but I saved the pdf to a single page and tried to attach.

I took a look at the site linked on the PDF you posted (http://myoutdoorplans.com/brags/diy-brick-pizza-oven/) for reference of others

I would strongly suggest not building an oven to that plan. It's an un-insulated barrel oven with a poor design for the flue - coming right out of the cooking chamber. It won't get hot enough, and it won't stay hot. Spend some time on this site researching. That oven is a very poor design. You will end up wanting to tear it down and start over. There's been more than one thread on this site over the years where builders have come looking for advice on how to fix that style of oven when it won't get to pizza temps.

edit: Do a search for "Brickwood" ovens on this site. That plan is about the same as those ovens. You will see the issues. Barrel ovens can work great, but not that design

https://community.fornobravo.com/sea...rickwood%22%7D

[deejayoh]

Actually.... more on this. The design that you linked won't work. However - that builder made a mess of the original design.

The original design has the flue over the vent like a proper WFO http://myoutdoorplans.com/pizza-oven...-oven-plans-2/



The builder of the oven in your pdf interpreted the plans a bit poorly and just decided to put the chimney on top of the barrel. Oops!


I guess that's why it takes him 8 minutes to cook a pizza!
Go back to the original design when you build your oven, add insulation under the floor and around the barrel, and it will work better. However, I would still suggest a dome. But I am biased

[david s]

Actually.... more on this. The design that you linked won't work. However - that builder made a mess of the original design.

The original design has the flue over the vent like a proper WFO http://myoutdoorplans.com/pizza-oven...-oven-plans-2/



The builder of the oven in your pdf interpreted the plans a bit poorly and just decided to put the chimney on top of the barrel. Oops!


I guess that's why it takes him 8 minutes to cook a pizza!
Go back to the original design when you build your oven, add insulation under the floor and around the barrel, and it will work better. However, I would still suggest a dome. But I am biased

I agree too. Many folk think a barrel oven is easier to build than a dome so they go with that design. Unfortunately a barrel oven is not a stable structure and when you throw heat and uneven expansion into the mix these deficiencies are highlighted. The design in the plan shows the back wall butting against the vault. This is a fault because the expanding vault will want to push the back wall out. You need to build the back wall under the vault to prevent this. Also the vault arches in this plan are all separated, they are greatly strengthened if tied together (staggered), this is slightly more difficult because you need to create formwork for the complete vault and also need to cut a few more bricks. Lastly, because of the inherent instability of the barrel arch it should be either braced with buttressing and/or steel bracing (at least that is the recommendation for kilns of this configuration and a WFO is basically a low temperature kiln)
Build a dome, it's actually less complicated, self supporting, better circulating, more efficient and a couple of thousand years proof of superiority.