Author Topic: Smallest possible dry-fit brick oven possible? (Read 2481 times)

EndUser · « **on:** June 10, 2012, 05:16:07 PM »

Hi! I would like to to build the smallest possible, dry-fit brick oven (outside) as possible. I want to be able to disassemble easily and move it too. Are there plans for the MOST efficient design? I don't need a tall stand, and I don't need any fancy aesthetics.

Thanks!

pizzaneer · « **Reply #1 on:** June 10, 2012, 09:40:35 PM »

There's been a few posts here about doing temporary brick ovens. It still comes down to two immediate factors: how large does it have to be to hold BOTH a fire and a pizza, and what do you have to work with?

Minimum size: 36" wide, 18" deep (for a side fire) or reversed if you want to try the half-barrel thing. Regardless, you will need a sturdy stand and a lot of bricks, some brickmold, and random parts.

Good luck!

EndUser · « **Reply #2 on:** June 11, 2012, 12:11:57 AM »

Thanks. Question, I have a concrete patio and a concrete pony wall against it... can I safely use it as a base to support the firebox? I don't want to harm the patio or wall concrete though.

JConk007 · « **Reply #3 on:** June 11, 2012, 08:26:37 AM »

My friend sells the small 1/2 barrrel oven sets up in minutes ! around $1000.

Chicago Bob · « **Reply #4 on:** June 12, 2012, 09:35:48 AM »

Quote from: JConk007 on June 11, 2012, 08:26:37 AM

My friend sells the small 1/2 barrrel oven sets up in minutes ! around $1000.

John,

How well does your friends oven cook pizzas ? Do you know how many minute pies it cooks? Thanks!

Bob

scott123 · « **Reply #5 on:** June 12, 2012, 12:36:13 PM »

Enduser, from what I've seen, very few people have ever pushed the limits on low thermal mass ovens, either mortared or mortarless. If you are, for the sake of portability, going with less thermal mass, you're entering into somewhat uncharted territory.

I see, from your profile, that your favorite pizza is wood fired NY. If you are, indeed, looking for NY bake times, that might give you a little more flexibility when it comes to materials, but, at the same time, you will loose a bit of flexibility when it comes to size. A huge part of what makes an Apizza Scholls pizza great is it's size- 18". Smaller NY style pizzas just aren't as good. To accommodate an 18" pizza, you'll need a pretty big hearth- maybe 22" deep x 38" wide.

I don't think I've ever seen anyone do this, but with proper insulation, firebrick splits (half thickness bricks) should work for the hearth. For the ceiling, you could probably get away with even less thermal mass. I don't have a lot of faith in oil drum thickness steel, but, again, with good insulation, you might be able to get away with 1/4" or maybe even 1/8" steel plate. If you really want to approach the thermal mass aggressively, you might be able to get away with cordierite kiln shelves for the hearth. Generally speaking, the smaller the shelf, the more thermally durable it is, so I would shoot for a few smaller shelves rather than a huge one- maybe 6 14 x 16 x 1/2" shelves arranged in 2 rows of three.

This is also completely uncharted territory, but I think you might be able to get away with 1/8" steel plate on the walls, perhaps supported by angle iron.

At the end of the day, the hearth, walls and ceiling will most likely be the easiest part of the project. Insulating, weatherproofing and venting it are going to get tricky.

Board insulation is sturdy, portable and light, but is costly. I've never cast perlcrete, but I get the feeling it may not be all that durable riding around in the back of a car. Blanket insulation is great for keeping the heat in, but I don't think it's something you want to handle frequently.

Board insulation might be waterproof, but it will still be sitting flat, so, for drainage, you'll need some sort of structure on top of it. You could probably put together a plywood structure that will travel flat.

Ideally, you want a chimney with some thermal mass, but you might be able to get away with well insulated steel.

pizzaneer · « **Reply #6 on:** June 12, 2012, 01:45:59 PM »

Scott, that's just spooky. How do you sniff out the NY pizza people like that?

I'll chip in my .02 for EndUser- you might want to consider an LBE if money's tight, space is at a premium, or easy transport are considerations. The 22.5" weber, fitted with an 18" round stone, or a custom-cut kiln shelf, would allow you to make the high-heat and large format NY style. Lots of posts here on building LBE's. Many happy users, me included.

scott123 · « **Reply #7 on:** June 12, 2012, 02:12:13 PM »

Brian, the first thing I do when I come across a new member is to look at their profile

That's a good idea on the LBE. It's far more portable than anything I'm describing and should have no problems with an Apizza Scholls bake time. I might go with a 19" stone, though, just to provide a larger target for an 18" pie. The smaller gap would probably preclude the chance for Neapolitan bake times, but, for NY, I think it would work- with proper deflection and ceiling configuration.

EndUser · « **Reply #8 on:** June 16, 2012, 03:23:52 PM »

Hi all, thanks for your inputs. A few clarifications. 1. I don't need to move it in a car, this would basically be stationary, but I don't want a big 'commitment' to it in case I decide to put it in a different place later, etc. So, portability requirement is limited, just not mortared/concreted in place. 2. I want a small visual footprint, and if I put it on my concrete patio I don't want a large physical footprint to take up useful space for sitting on my patio.

I'm looking to avoid archways and complex design features, just something I can setup and go. Should look nice and simple, rectangular and modern, not going for old-world charm etc.

I would love to increase thermal mass and go for the Neapolitan cook times. Weight is less of a concern than size.

Thanks!

scott123 · « **Reply #9 on:** June 16, 2012, 03:37:02 PM »

This should be pretty close to what you might want to build:

http://www.pizzamaking.com/forum/index.php/topic,18213.msg182623.html#msg182623

I would add a chimney, though, and make sure you insulated every side, including the bottom.

Michael130207 · « **Reply #10 on:** June 16, 2012, 04:20:07 PM »

I built that oven so I figured I would offer an update/advice. I still use it about once per week. No problem yet with angle iron failure but it has only been a few months. It achieves really good temps in about 2 hours, 1000+F ceiling 800F floor. I can easily make 14 inch pizzas in it, about 6 per hour. The size limitation worsens with the centered door so I have offset it to the side opposite the fire so that I can easily get my 14 inch peel in and out to launch the pie.

If I were to do it again, and I might, I would do the following:

1) Keep door offset to opposite side of fire.
2) Elevate it on a platform. I have designed and bought lumber to build a 24 inch high platform, 6X6s and 2X8s covered in concrete pavers then 4inchs perlcrete, which makes it a squatting event, rather than a kneeling event to launch a pizza. I don't want it high because when I'm done making pies, we open up the front and all sit in front of it like a fire place. Really nice on a cool night. Make smores and such.
3) Instead of making panels I would build a form and pour perlcrete insulation 4 inches thick all around. If I move or the angle iron fails, crack open the insulation and call it a hundred dollar expense. Cover the thing in stucco.

Thats my 2 cents. Go for it, nothing like cooking in WFO! Ton of fun.

EndUser · « **Reply #11 on:** June 16, 2012, 05:27:24 PM »

Good stuff!

I'm thinking about a variation between your oven and this one: http://www.fornobravo.com/forum/f21/foundation-first-pizza-4-1-2-a-6653.html#post54492

My questions are, what if I used a 1/2" steel plate instead of angle irons? Would that help with the thermal mass? Then I could get it cut to the right roof size and I could use regular clay brick instead of fire brick on top of the steel. Thoughts?

Also, how important is it for the opening height to be lower than the inside height?

Thx!

scott123 · « **Reply #12 on:** June 16, 2012, 06:17:54 PM »

Enduser, the steel plate should help to evenly distribute the intense heat and prevent the regular clay bricks from failing, but there aren't any guarantees. With the set up you're considering, it may not be the end of the world if the clay bricks crack, but if they cracked violently, you might have a problem.

There's really no way to know for certain, but, I think your odds are pretty good that you'll be alright with regular bricks.

It's important that your bricks are weatherproofed/stay dry, but with regular bricks, this is even more critical. If even a single drop of water gets on a 1000ish deg. regular brick, it is NOT going to be a happy camper. This might be a question for the Forno Bravo folks, but I'm not 100% certain that you can apply stucco on top of perlcrete, and, if you do, whether or not it will be weatherproof.

Re; 1/2" steel. You could probably get away with 1/4" or maybe even 1/8", as long as it's flat and the bricks sitting on it are contacting the surface evenly. Angle iron is 1/8" and that has no problem supporting bricks at typical ceiling temps.

Btw, I haven't seen a whole lot of experimentation with a ceiling comprised of only steel plus insulation. I don't think you'll be able to do much in the way of residual heat baking, but, with a strong fire, I think a low mass steel ceiling should work perfectly fine for pizza- as long as you've got a couple inches of perlcrete on top of it.

Lastly, I like the idea of casting one huge block of perlcrete, but, one of the nicest things about a mortarless oven is that, if some aspect of your configuration isn't quite perfect, you can take it apart and rebuild it. If you lock everything in with perlcrete, you lose that ability.

EndUser · « **Reply #13 on:** June 16, 2012, 06:29:56 PM »

I am not familiar with perlcrete. I was going to use clay bricks onto as the insulation, is that not sufficient?

I have an interesting design I'd like your opinion on. I'd like to do a corner/angled version of the brick oven, I would use 4 2'x2' pavers on cinderblocks as usual, but on the platform I would arrange the bricks at 45-degree angle. This would give a nice landing area in front too. Check out the attached concept pic.

Tscarborough · « **Reply #14 on:** June 16, 2012, 07:21:18 PM »

If you are going to that much trouble, just build a real oven.

Michael130207 · « **Reply #15 on:** June 16, 2012, 07:45:25 PM »

I like your design, make sure you have good clearances to combustibles depending on your insulation. Looks like you could keep active fire to the side and pizza to the other side.

I like the solid plate idea, However much of the strength of angle iron comes from the increased moment of inertia from its shape. Angle iron is much stronger than 1/8th inch bars. A solid plate is also going to be very heavy, 1/2 inch may weigh about 250lbs. And I agree will likely be plenty strong. The nice thing is you don't have to worry about pieces of insulation brick or mortar falling in your pizza.

You must insulate it though. Brick will not provide insulation just thermal mass. Perlcrete is one part Portland cement six parts perlite.

Mike

EndUser · « **Reply #16 on:** June 16, 2012, 10:07:57 PM »

Are there other options for insulation material? I'm trying not to pour any moulds as this is to be 100% dry-fit.

pizzaneer · « **Reply #17 on:** June 16, 2012, 10:24:40 PM »

Rockwool could be your answer. You can lay it on your dry-fit bricks in batts, but you DO have to provide moisture protection, as the rockwool will soak up rain. Do this by building a weatherproof enclosure... concrete board, steel framing, shingles...

Seriously, this is getting more involved than it has to be. If I were you, I would just go ahead and install a decent oven, and not worry about moving it someday. It will add to the selling price of the house, even more if you do the whole outdoor kitchen thing. Then after all this experience, once you get your dream house, you can get your dream oven, instead of recycling an expedient.

EndUser · « **Reply #18 on:** June 16, 2012, 10:30:55 PM »

You are right, thats getting too complicated. I dont have a good space to cover it. Maybe I will do without insulation. I need to simplify this design.

scott123 · « **Reply #19 on:** June 16, 2012, 11:10:09 PM »

Quote from: EndUser on June 16, 2012, 10:30:55 PM

Maybe I will do without insulation.

An insulated WFO will take forever to heat up, and, unless you're using an inordinate amount of thermal mass (quite a few bricks thick), you'll have trouble retaining the heat as well. Perhaps if you had unlimited free wood at your disposal, it might be feasible, but, even then, it's really inefficient and wasteful. In addition, the insulation protects your weatherproofing structure from heat, so, once you lose the insulation, it becomes really hard to weatherproof. As I said before, 1000+ deg. regular clay bricks + water = dangerous situation.

There's no shortcuts for this. You need a firebox layer of firebricks or steel, and if steel, then some additional thermal mass in the form of regular clay bricks. On top of that, you have to have some sort of insulation- rockwool, board, insulating firebrick, perlcrete, etc. Lastly, you've got to add a chimney and protect this structure from the elements. All of these elements are critical in making an oven that's safe, durable, efficient and that will give you the results you're looking for.