42 inch Pompeii Design Build

[antzvu]

Hello everyone. I wanted to share what I'm working on, but also get some advice on my design/build.

Before I build anything, I usually go through a design stage for my woodworking, so I suppose this would be no different. I'm trying to build this dome oven virtually before I get my hands dirty to see what issues I'd be running into during the build.

This build is going off the ePlans from Forno Bravo, but I'm trying to see if I can make it a smaller footprint, or if it's even worth it to go smaller like 36" WFO instead.

[david s]

If you build a 42” oven you won’t be wanting to fire the oven up just to cook 4 pizzas for the family. It’s fine for a really big party, but generally most folk will only cook one pizza at a time as they take longer to prep than to cook. The angle iron supporting the bricks over the entry of the wood storage is a rather odd and unconventional method. A better and more normal way is to use lintel blocks, also sometimes called bond beams or knock outs. Which you fill with reinforcing bar and concrete, leaving no exposed steel. Rather than building a bomb shelter under the oven you can save on blocks to support the concrete slab by cantilerering which also reduces the spa at the wood storage entry. A cantilevered slab requires some slightly more complex formwork though.
Also your plan shows the dome bricks (first course) sitting on the supporting slab. They should be sitting on insulation to prevent heat conducting to the concrete under them. Also you have the first course laid vertically (soldiers) which I know the plans recommend), but it introduces a tall vertical joint in the weakest point of the dome. A stronger method is to create all courses laid flat with staggered joints. The only advantage of laying soldiers for the first course that I can see is that they give you a little extra height at the base of the dome. The same can be achieved by laying the first two courses flat but rising vertically.

[antzvu]

Thanks for the advice David. I'll make changes to my design.

I definitely don't want to build a 42" if I don't HAVE to. But on average, I make a total of 8 pizzas every time I fire up the lil Pizza Pronto which is what I'm currently using now.

I'm still torn about going between the 36" and the 42" builds. I would regret it if I built a 36" and wish I went 42". Yeah, I know, First World Problems right?

[antzvu]

Here is the updated floor.

[antzvu]

Here is the oven door build. I'm not sure if it's correct. The bottom bricks on the sides do not sit on any insulation, but I figure since it's the door, it doesn't have to. Is this correct?

[SableSprings]

David certainly hit the main issues with your initial plan and you fixed those "problems" pretty well with your next set of drawings. One thing I'm not seeing is the inclusion (or mention) of a reveal (door stop). Here's a link to two basic views of what the reveal should look like (note: the first reference link in the thread post #1 has a disconnect). The link to post #8 shows the old style "square" oven entry with the reveal and following it, in Post #12, you'll see an extra large arch entry reveal.

https://community.fornobravo.com/for...4377#post24377

When you start looking through the forum builds, you'll notice that a reveal is an important feature if you ever want to bake bread or roasts, etc, with retained heat. Hopefully you have looked at several of the well documented builds linked in the Newbie forum sticky topics, especially check out the thread noted below.

https://community.fornobravo.com/for...n-the-archives

Your door sitting on the bricks in front of the reveal is fine, although many people have built in a narrow gap between the oven arch and landing...basically isolating the oven to minimize heat loss. (It would be located on that front face in your first drawing, post #5.) There is also the school of thought that the amount of heat lost out of the front face of the oven is very small, especially when you have an insulated fire door and a good fit with the reveal when it's closed.

The front arch will be tied in with the dome, but you might want to build in some buttress support on the next, outer arch. That's mostly if you are thinking about putting more than just a smoke collection chamber leading to a stainless steel chimney pipe.

I think that you will want to decide how much entertaining is in your future when sizing your future build. It is also important to realize that you don't want to be standing on grass while working the oven...because it will turn into dirt/mud pretty quickly. You also will have a fair number of people at a party that will want to watch or participate...again, it will be a space issue for your WFO entertainment center. Having a large enough slab (or patio stone) for the area in front of the oven stand is going to be really important to you down the road (IMHO). I really like having enough working area (table top/side wings on the top slab) near the oven to prepare and serve food. That said, bigger isn't always better, David S has had some whopper parties and pushed a lot of pizzas out from his ~21" cast oven to feed the masses.

Don't forget that adding some weep holes in your slab and providing a barrier between the slab and ceramic insulation board are strongly advised. (Lots of options for the moisture barrier, here's just two - mosaic tile sheets or the spendier, but perfect, FoamGlass.)

I hope that helps a little...drawings look great!

[JRPizza]

I was also stuck deciding between a 36 and 42 inch oven. Decided to split the difference and went with 39" . I took the door opening recommendations from the FB plans for a 36 and 42" oven and interpolated to get a size, which almost exactly hits the 63% opening to internal dome height recommendation, so I thought that was a sign that I was on the right track. 39" is almost exactly a meter, another good sign.

			Opening	Opening	Ratio
	ID	Height	Width	Height
36"	36	18	19	12	66.67%
39"	39	19.5	19.5	12.25	62.82%
42"	42	21	20	12.5	59.52%

We are happy with the size and often have several pans, pots, or trays going at once. Like David says you probably aren't going to cook more than 2 pies at once, and I only ever do one. They cook so fast and need lots of tending/turning that I would probably burn them if I tried to do more than one.
Lastly, I would recommend looking at a semi-circular arch, as they are visually appealing (imo), and structurally stable. The flatter type arch you are showing often requires buttressing to handle the side loads.

[JRPizza]

I also agree with David that the angle iron above your opening probably isn't needed. The slap is going to span the width of the stand, so it should be able to span the smaller opening. If you look at my build, I just made sure I had rebar in sufficient amount and location to support the slab.

[Chach]

As far as the wood storage entry you can use the angle iron and put bond beam on top and notch all your top block in the front and lay a piece of rebar over the top course above the opening and when you fill your courses with concrete fill that solid too. the angle iron basically is there to just hold the block until you pour it solid.

[david s]

The attached pic shows a method that allows easy removal of the timber support once the concrete has cured. A couple of blows with a hammer on each end will remove them easily. Cut a length of 4x2" exactly the length of the span and hammer two 2 mm nails into each end as shown, allowing them to protrude about10 mm. They need to be 10 mm from the top face to allow for the thickness of the mortar joint. If you think they need more support you can place a prop under the middle, but you shouldn't need to do so. I built a whole house and used this method for all the doors and windows.You will have a nice clean face, no ugly rusty angle iron. Provided you fill the channel in the bond beam blocks with at least a couple of steel bars and concrete, it will also be way stronger than some external angle iron.

[Chach]

For sure this is another way to go...I have seen them build bond beams on the ground 2 block high install rebar pour it with grout and have it cure for at least a week then lift it with a Lull and set it like a beam. The span was at least 8' - 10' pretty amazing. Not that what you drew is complicated or hard.it is a pretty detailed drawing but the angle iron is pretty idiot proof but I do like david s angle ironless way better it is a cleaner look especially if you choose not to face the bottom with a stone or brick. If your stucco the bottom I would really consider david s way for sure no doubt.

[antzvu]

Thank you everyone for wisdom. This project is quite the undertaking.

Ok. Looks like I've settled for 39" WFO. JRPizza, I felt like an idiot for not thinking of that sooner, especially since I tell people to split the difference all the time.

In terms of the base, I may design it after I get down the dome. I want to gauge how much play I have for the base. I may actually pour cement for the entire area just to establish a backyard kitchen.

[JRPizza]

New sketches look good! Don't know if the floor bricks represent actual layout, but if you shift them slightly forward towards the door you can eliminate the small pieces right at the entrance. This arrangement also places a brick close enough to the center to allow the use of a "wooden brick" to mount your IT. I also attached a link to my hearth build so you can see how I maximized the height of my wood storage opening. I'm glad there isn't a layer of brick or angle iron at the top of my opening - I have enough trouble not bumping my head with it as is.

https://community.fornobravo.com/for...324#post380324

[UtahBeehiver]

I do want to recommend that you consider a tapered inner arch. Takes a little more work on the front end but will save time and also allow for a smoother transition to tie in the dome to the arch. There are a lot of examples out there and worth the effort. But requires full bricks on the arch not half bricks like the current design shows.

[Chach]

New sketches look good! Don't know if the floor bricks represent actual layout, but if you shift them slightly forward towards the door you can eliminate the small pieces right at the entrance. This arrangement also places a brick close enough to the center to allow the use of a "wooden brick" to mount your IT. I also attached a link to my hearth build so you can see how I maximized the height of my wood storage opening. I'm glad there isn't a layer of brick or angle iron at the top of my opening - I have enough trouble not bumping my head with it as is.

https://community.fornobravo.com/for...324#post380324

I agree I wish I would have not only had the extra head room but I wish the opening was wider. I wish I didn't return the front walls in and just left the opening as wide as possible...Im not getting any smaller in my older years lol.