36" Pompeii in Indiana, US

[GreenViews]

Greetings from Northern Indidana, US.

I am Tom and decided to build an outdoor oven a couple months ago. I have the base below the concrete table the oven will sit on just about complete but am still working on plans. I was leaning toward a barrel type design similar to brickie in Oz but am now likely to build a low vault Pompeii style oven as close to given design specs given in the design download v2.0 as possible.
My plan so far:

• 3" Calcium silicate board for insul layer - will level on top of my extra large table top which will slope away from patio very slightly
• 2.5 x 4.5 x 9" low duty fire brick - sourced with some on hand
• used brick unknown quality -has mfg stamp "superior", seems to be firebrick, Their web site is less than helpful, but perhaps medium duty brick. Not sure I have enough non-chipped for cooking surface, so was considering for lower thermal layer.
• refractory cement power mix and small amount of castable refractory from hardware store
• Ceramic fiber insulation and Perlite for dome insulation layer
• a dozen insulating fire brick (can get more if desired) for thermal barrier between fireplace and entrance
• some 6" clay tile (was buried at my property) for chimney. I realize I may need 2 of these side by side and transition from a rectangular arch vent to a dual clay tile chimney, but that might look interesting
• Some brick and other materials including old slate roof for yet to be designed outer structure

Some of my questions at this point:

1. High vs low vault? I see more people doing a high vault pattern rather than a low vault pattern oven. I thought I would try the low dome, but wonder if it is too challenging of a project. I also wonder, since it doesn't hold to the 63% chimney to dome ratio, will it still be good for other types of baking (I think yes because of retained heat and closing the oven door after fire out, but please provide feedback if you have thoughts or experience).
2. Just a note: On the Right side of my drawing, I started with 4.5" brick side for courses, then realized that would mean the half brick were in kinda soldier patter each course, so on Left side I drew with each course only 2.5" (or less because of cut) high.
3. Soldier course too aggressive?: I'm considering with this low vault design (as given in v2.0 ofFB guide) that maybe my drawing with a beginning soldier course creates the need for a too agressive arch which would be less tolerant of build errors (my inexperience) as well as create too much pressure outward pressure on top of soldier course (I could buttress with insulating castable, but less efficient insulation). Should I start with half soldier? I'm kinda thinking yes and maybe 2 half soldier with second soldier starting to tip inward, so course 1 and 2 being 4.5" tall and starting on my lower thermal layer with top thermal layer set inside the dome build, but feedback is VERY welcome.
4. Too low arch radius? Maybe basket arch instead? Related to above question: the center of my arch with this design was 9.5" below the floor and when I looked at the cuts and closeness to vertical, I got pretty scared about stability, so definitely leaning heavily toward smaller soldier course to pull center of arch radius up quite a bit. Possibly move toward a higher vault if I still feel uncomfortable. I also wonder if a 3 centered basket style arch might be used rather than a soldier course to keep some good rise on sides while allowing to bring main arch center up considerably without raising the ceiling.
5. How much cutting to brick to meet parallel? In my drawing, I assumed starting courses above the soldier with bricks cut in half. My other idea was to have a 2" cut on either the top edge of the lower course or bottom edge of the upper cours so there would be a 2" parallel meeting of brick surfaces between each course.. then a very thin as possible mortar joint with larger joint in back of course to fill in. I hadn't though of the joints between brick around each course yet. Should bricks be cut more or less than my plan of 2" parallel surface area between bricks? Is this more important or equally important for the joints between bricks of a given course or between courses? I understand that a principal goal for hot face is to minimize mortar on hot face. What about structural integrity? would widening mortar joints between the brick be cause for concern if half of the brick width is cut to parallel surface match? I see some builds with minimal cutting and mostly mortar joints used for wedging. If I want my oven to last 25 years, what might a good trade off be?
6. How much floor thermal mass? Some sources say floor thermal mass should be greater than dome for best heating characteristics, but I see many builds with a single course of firebrick and smaller thermal mass on floor. I'm considering 2 layers, but would a good trade off be using splits (1.25" wide brick) on top layer which would be set inside dome? 2 thoughs for this possiblity: I have only sourced low duty firebrick locally so far, so less work to replace oven floor or part of it if needed and the other thought is with 2 full layers on floor plus a little fire clay mix between layers, would the oven take too long to heat up? On the flip side, would 1 full and 1 split layer with a thin fire clay based layer be too thin for proper cooking other than pizza?

Thank you all for any feedback. I'm excited to join this community and excited about my build... even if a bit apprehensive at this point.... my base below my oven is nearly done and I'm not yet ready!

[UtahBeehiver]

Quite an intro. Nothing wrong with a low dome, just not as many on the blog. The 63% ratio is for a pompeii but FB does give some suggestions.

Take a look at KarangiDude's latest oven it is a barrel, his first was a dome. He did a first rate job with design and execution. He also buttress his oven correctly. KD, does a lot of cooking other than just pizzas.

[danhem]

Hey GreenV, interested to see the start of another 36", not much in the way of master masonry here or build quality but a few comments nonetheless;

High vs low vault? - I think the high vault is a less challenging build. In saying that, utilizing the home brew as recommended here, i don't think the structure of the build would be compromised in any way. I can only say that as a pompeii dome evolves, the geometry and shape of the build will remain dear to you (and most likely only to you) for as long as the oven lives.

Soldier course too aggressive? Depends on which way go on the vault depth I think. If going for a low vault I think you have to set a soldier course. For a higher vault there are a couple of chains of thought depending on whether you wish to lay the first course on top of the oven floor, or building around the floor. I built on top of the oven floor as it seemed to be the easier option. I do note that a lot of the quality builds build around the oven floor...probably my first (of many) mistake!

How much cutting to brick to meet parallel? Seems to be a lot of brick cutting during the build. there are perfectionists on the forum that have produced unbelievable works of art with cooking efficiency to match. Tapering each brick to fit snug is time consuming and requires skill and patience. To get a the picture perfect inner dome however, a less time consuming bevel cut can be applied. This will create a tight inner dome joint but leave a wide gap between the bricks on sow outside. Simply fill gaps with mortar and no one will ever know. I think it is UtahBeehiver that says 'mortar is your friend' in these situations.


Good luck going forward. It's a challenge but a worthwhile one with amazing end results. Sounds like you are preparing well with the right questions. All answers are buried somewhere on the forum - an unreal pool of knowledge and experience.

If I could start again, I'd follow one of the better builds posts by post, copy them and make a many less mistakes.

[Chach]

Before I built my oven I was leaning towards a barrell because not only was I was uneducated on ovens in general but also that was the first type of oven I saw when looking. I did however start to look into ovens and saw the dome oven and thought it would be more difficult so I was going to do a barrell. Once I started to look even more into the ovens I came accross this site forno bravo and learned the pros and cons of each type and how they cook. I'm glad I made the decision to make a dome oven instead of the barrell oven. In my eyes it seems more traditional and I think the way it's constructed makes it a more efficient cooking device. This is how I decided on how I was going to construct my oven.

Ricky

[GreenViews]

Thank you for your feedback. I have new drawings and hope to pour my table upon which my oven sits tomorrow. I feel much better with the new drawings with 2 half height "soldier" courses with the second one tilted to bring everything back to the main arch. This in effect creates a mini basket type arch with 3 center points, but only with the first 2 cuts. I also have a drawing of my opening arch. I'm considering using half bricks for this arch followed by half insolaating bricks in a square opening using angle iron. This would allow me to be very versitale in my door with either a square door or a curved top door. It would also allow better access into my oven, but perhaps at the cost of aesthetic value? Thoughts? I'm really getting excited about being able to start my oven in earnest!!! I also bought a CHEAP 10" tile saw today from Harbor freight, but bought the 2 year extended warranty, which was in effect paid for by a coupon price discount. So worst case, I'm out $60 if saw doesn't hold up for the project.

[UtahBeehiver]

A lot of builders have used the old HF saws for their builds. Mine is still going after 10 years. Here's a hint for making the water pump last. Buy so plastic tubing and extend the outlet so you can take the pump out of the tray where all the sediment is and place in a homer bucket that you fill with a hose and you always have a clean water source going through the pump. You have to take in account of the different expansion ration of steel vs brick if you are considering angle iron. The iron will expand more than the brick and could cause cracking. Some buttressing still may be required if you do a low dome.

[JRPizza]

The clean water bucket is good advice. I actually used two buckets - one at the saw end that I filled with clean water, and one at the opposite end that I placed under the drain hole (didn't use the plug) to catch the dirty water. I cut so slow that my tray was filling up with water and dumping a tippy tray without getting wet feet was problematic. The dirty water bucket did the trick.

[GreenViews]

Great ideas on the clean water bucket and dirty water buckets! Just poured table last night. Soon will start adding curing wood under it and be able to start mock layouts. I suppose I should build a canopy over work area to keep rain off of project?? Also, draining of CaSi board... maybe place on checkerboard ungrouted tiles to allow draining underneath? Finally, the entrance arch. I'm thinking of making out of half brick rather than full brick to give me room for half insulating brick setback next and a lower profile opening. My drawings seem to suggest this might be enough material for the arch, but any experience here?

[GreenViews]

To keep opening tighter, I'm considering just a half brick wide inner door arch followed by a half to full wide insul brick for thermal break and flue opening area followed by decorative outside face. My question is those of you who have used half brick door arch, Do you find it adequate? My drawings seem to suggest it could meet up nicely with my low dome with enough brick left over for durability. Your experience? Do you wish you used more brick? I'm also not thinking about the possible need to keep any moisture from the CaSi board... raised a question above. set on tight ungrouted tile mesh? drill drain holes through concrete? I do have a very small slope on the top away from patio which I will need to address. tapering mortar layer under CaSi or under the tile mesh supporting it if I go that route? Very open to your thoughts on any of this. Getting excited about being able to start in earnest soon!

[UtahBeehiver]

spaced out ungrouted tiles have been used by other builders where the spaces channel to the weep holes. Just the cheapest tiles you can find would work.

[GreenViews]

I have some used 12" porceline tiles from my last kitchen remodel which I decided I don't have a use for. Should I break smaller? What size weep holes are you using and how far apart?

[UtahBeehiver]

Just leave whole, the point is to raise the CaSi off the concrete hearth. 3/8 - 1/2" 3 or 4 then silicon some wire mesh on the bottom side to keep bugs out.

[GreenViews]

Oven placement: Which is better? very close to edge of table or a few more inches back. With a few more inches back, I can still reach my hand just past the door without bending over. My oven base is higher than normal perhaps. It will be almost 8" higher than table so sternum level to me. Low dome 15" with 9.75" high door.

[JRPizza]

Can you tell us why you want to use "insul brick" as part of your vent support? Also as far as using a half brick for your inner arch - the arch needs to intersect the dome if you want to keep the dome round. There is some allowance in fore-aft location that can shorten or lengthen the distance from the center of the oven to the front of the vent arch so you should do some layouts to see how short you can make it and still work. If you look at the attached sketch of my oven you can see where I have some arch brick projecting from my dome at the bottom and more projecting from the top as the dome curves rearward. I could have moved the arch inward towards the centerline of the oven but wanted to maximize internal floor space. You can check out golfguiedo 's build - he's just starting and has his arch moved about as far inwards as practical. You have a few inches of in-out to play with, but you will certainly end up with more than a half brick for at least part of your inner arch.

https://community.fornobravo.com/for...art#post422716

[GreenViews]

The insulating fire brick I bought are Lynn Manufacturing IFB 2300F Rated lightweight ones. Maybe I couldn't put much weight on them, is that a question? I bought them on Amazon.com for a thermal break between the oven and entrance. Looking up specs, looks like 115 psi is modulus of rupture, with cold crush strength at 145 psi, so if I lay 3" angle iron across the 4.5" side, I have 14.5 sq inches, so I can safely stack 14.5 x 115 x number of places angle iron crosses top of brick. I was only thinking of putting one course of brick on top plus some clay flue liners and high temp cement (don't have final plans), but I think I have a lot of weight room for what I'm thinking of using for. I would leave space on each end of the angle iron to expand: not thinking of cementing them in, just floating material on top of them and outside the thermal break at that, but in the chimney which will get hot. Thanks JRPizza for your sketch!!! I had seen it somewhere it turns out and nice cad skills!!! In my drawings I show my opening just a little into my oven if I build my arch where the top of it intersects the dome on the lower corner of each which is what ijt looks like you were going for as well. I did want to cut back the front edge of my fire brick inside the oven to keep my chamber as large as possible and avoid corners for ashes to catch behind, but it seems there would be plenty of brick left over using halves for support.. but maybe I'll be safe and use 2/3 or 3/4 bricks rather than halves for the arch. I think anyway that the advice I'm getting is better safe than sorry over a miscalculation. I'll take it! Love the advice coming my way! Thanks! I just picked up some metal insect screen for under my CaSi board. I'm hoping to get weep holes drilled out today and if I'm lucky level and set my CaSi board.... but other chores to complete first, so let's see what I can do.