pompeii oven construction began today

[ColonelCorn76]

Ah. I knew you made it round but didn't realize you were putting the walls outside the hearth. What kind of gap are you putting between the hearth bricks & the wall bricks? It seems to me that if you butt them, there's a decent chance that expansion of the hearth bricks will move the wall bricks over time (very small forces here but perhaps enough to create cracking). The advantage of the walls on top of the hearth bricks is that they can both slip. Also, your wall bricks are flat & your hearth ones are radiused now which means you'll get little wedges of space between the hearth bricks & wall bricks no? I would expect those to get filled with ash & debris over time -- might want to fill them with fireclay before the walls get too high to provide more consistent thermal properties across the whole structure.

It's probably not a big deal (even with the walls on the hearth bricks you'd mortar down around the whole thing but the impact of the conductivity channel is more direct brick to brick). I'd go with no mortar but put the walls on a layer of fireclay/sand so at least the whole thing can slip relative to the concrete hearth consistently. I'd also still butter the mortar around them as well. (Remember the mortar here is fireclay enhanced to mimic the thermal properties of the firebrick.)

Jim

[paulages]

yeah, jim, i think what i'll end up doing, is fireclay slip pan between the wall and floor, and under the wall and hearth. i will mud in between the bricks and behind on the first course, and use high temp. insulation caulk at the base to unsure no leaks. unless i'm misunderstanding the specs i found on these bricks, they should contract when hot, and expand back to the size i set them at at ambient temperatures. the specs were for a 2% contraction at 2500 deg. F or something like this, so i can't imagine the barely-pushing-freezing temperatures we get here in the pac NW will cause them to expand much.
i was initially concerned about these small wedges you are describing, and was going to cut the circle to fit the walls exactly. but then i set them up and realized that the difference between a 2" brick sitting against a 132" diameter circle and a 56-agon (whatever you'd call that) was miniscule. some places it fits almost completely snug, and others there's maybe a 1/16th" gap.
i saved all of the sludge from cutting the bricks (maybe 1/2-3/4 gal. worth), and plan to try using this as a paste to fill any gaps.

danutsby (whatever your name is),
if you're in the portland area, and want help, just contact me. my # is 503 247 7610. the reason i'm describing all of my mistakes and discoveries so thoroughly, is precisely to help future builders. it's all of the previous plans and posts on here that have helped me get this far. hopefully people can take what those who have built have done and improve it.

[paulages]

here's the brick for my door header... (18" wide, 11 1/2" high at apex)



and here's the prototype for my dome. note the pile of shims, numbered-corresponding with each course. i would have done the whole thing with archway brick, like the last three courses, if they weren't almost twice as expensive as the regular bricks. the dome hight is about 17 1/2 inches.

[Keith Oertli]

Paul, great Door arch layout! Looks strong and sturdy.

Did you cut the brick at those angles, or did they come that way?

If they came that way, where did you find them?

I am enjoying your progress in pictures.

You are definitely one of those few people who are gifted with the skills to build anything well.

K.O.

[paulages]

thanks for the compliment keith. i don't know if that's true, but i do know that obsession and the power of reason can go a long way...

about the bricks---the supplier i bought them from, had four different archway bricks in the grade i am using. numbers 1-4, four being the most drastic. the supplier, HWR (hwr.com), apparently have warehouses in several states in the U.S. if someone could find them for a reasonable price, or if cost wasn't an issue, they would be perfect to use for the entire dome. absolutely no possibility of a brick working its way loose and falling through.

[james]

Arch/Door Header bricks

Paul,

Can you post more details on the arch bricks. I think a lot of people would be interested in using a preformed arch brick for their oven opening and for framing the vent arch. The tight brick arch is a nice look -- it looks very custom, even though you are using off-the-shelf bricks.

Any other details, such as part #, price, etc. would be helpful.

James

[paulages]

arch bricks

i'm gonna post this in a new thread, so it will be easier for people to locate in the future...

[paulages]

thanks for the idea, jim!

here's my forms for the header, and guides for the dome. i think i'll add even more vanes in, it is so easy to do. seems like it could get really nice to have these guides sufficient as forms at the top. i'm not actually sure they hold up, though.







now the fun begins!

[paulages]

update on progress...i've been too busy for the last few days to work on my oven, but got back at it today.





gotta go get some more bricks tomorrow. l leave on monday to japan for 3 weeks. wish i could complete the dome before then, but it's looking doubtful.

[Fabio Allodoli]

Hello. Fabio here. Nice job on the brick cuts, and like the idea of the Styrofoam ribs for the dome, it make perfect sense and easier than shiiming the corses of bricks. Any thoughts on the flute, and how deep is the entry way. Where and how far back or forward is the flute going to sit from the oven. I am in the process of building an outdoor kitchen with BBQ pit and counters, and planning this out is going to be very critical since the entire kitchen is going to be shaped like U, with overhead cover. I will be pooring a footing and start to build the brick courses up and then lay a 30' x 22' pad. I believe this way the stand for oven will be much stronger with pad poured around the brick courses.
Any feed back is appriciated and pictures anyone on the flute.

Thank you. Good people here trying to help and share their thoughts.
As I start the construction I will be taking picturers, with dimensions.

Ciao.
Fabio.

[paulages]

the entryway will be made of the exact same archbrick, extending forward 12" or so, with the vent just outside of the existing brick, like a tunnel with a slot in the middle of the top. can't make it until i finish this arch.

by the way, when i bought my remaining firebricks, the supplier gave me as many buckets as i wanted of refractive mortar. it had slighly dried on the top, so they couldn't sell it. i just scooped the top layer off, and it's good to go. kind of a bummer that i already have the fireclay, but this stuff has plenty of alumina, etc. in it, and oughta outperform the handmixed stuff. plus, i don't have to mix it! too bad i didn't ask for this in the beginning. drat!

...(edited later)
okay, scratch that. the stuff is a little too stiff, and though it is a nice pasty mortar, it would be much more work to get this stuff to the right consistency than it is to just hand mix the fireclay mortar.

[paulages]

by the way

i don't remember seeing anyone suggesting it, but it's really important to dunk the firebricks in water before laying them. they are so dry, they just suck up the moisture in the mortar instantly, resulting in less adhesion.

[paulages]

kim helping set bricks while i deal with the dome cuts...



this one sort of shows how the dome intersects the door header. the bricks are staggered in the archway so that the top of the section of arch that will be open for the vent will be anchored by the adjacent sections. (this will make more sense when it's done.)




i hope to finish the dome tomorrow, so this thing can do some pre-curing while i am in japan for the next three weeks. believe it or not, i've actually had some decent wood-fired oven cooked pizza in japan!

[paulages]

dome completed!

here's how the header tied in to the next course. not too easy, but not terribly hard.







i cut trapezoidal pieces for this---no measuring, just figured they'd fit more snugly, and they fit together like a puzzle...

[paulages]

dome completed!







it turns out that my brick supplier ran out of low duty firebrick in a 2 1/2 series, so iwent with the 3". bad idea. check out how much bigger the gaps are as the dome closes inward, and how much mortar shows (i haven't cleaned it up yet). at the bottom wouldn't have mattered as much. oh well, c'est la vie. i'll have to point some of the larger cracks with mortar when i get back from japan. or not...it is standing freely only 3 hours after completing it.