2025 Pompeii Oven Build Log

[yoboseyo]

Going to document my build here, and perhaps get some advice while I'm at it.

My project is an outdoor kitchen with a pizza oven and a fireplace BBQ. For now I'm going to focus on completing the pizza oven.

Specs

• 900mm ID
• Dome: Tapered Firebrick 115*230*75/63 (cut in half)
• Dome insulation: 3 layers of 25mm blanket
• Floor: Firebrick 115*230*75
• Floor insulation: 3 layers of 25mm CaSi board

Design Notes
Feedback appreciated on these - these are my ideas and aren't a part of any guide

Low(ish) dome
To "cheat" and lower the dome while still using my IT, I'm just going to build the floor into the dome rather than under it. That makes the inner height 450-75=375mm
In the spirit of a small oven, this is intended to reduce the volume enough to make it heat a bit more efficiently

Heat Break using insulating brick
I want to put solid insulating material for the heat break. That way the break and vent arch can be the flue (see pic 3). My idea is 25mm insulating brick.
Other ways I've considered are fill the gap with blanket and seal it with vermicrete; or inject high-temp silicone

Other Questions

• What should I make the chimney from? Pic 2 shows a 25mm firebrick construction. I can also make it from castable.
• Does the outer arch have to be made with firebrick?
• What should the vent hole dimensions be?
• Anywhere in Australia I can buy an 8" chimney anchor plate?
• Anywhere in Australia I can buy a metal pizza oven door? If I can buy one I'll plan my vent opening around it. Otherwise, can I make one out of wood?

Plans




Build Photos

[mongota]

I lived in Suwon for a year, so 'hello', yoboseyo!

Outer arch and thermal break: I start my fires in the landing tunnel, directly under the vent opening. As the fire progresses I push the fire back into the dome. During the initial fire, my vent tunnel gets direct flame and sees somewhat high temperatures, so my entire tunnel, including the outer arch, is made from firebrick. I used 1/2" ceramic fiber rope to fill the gap between the dome brick and the landing tunnel brick. Years ago I used a temp gun to shoot temperatures and slight thermal and structural break, plus the change in brick pattern on the floor (herringbone in the oven, running bond in the tunnel) indicated that the system worked. I have good quite good heat retention in the oven. Insulation, I have 4" of board under the floor and 4" of blanket over the dome.

Chinmney transition: I used 12 regular sized firebricks to make the transition from the curved top of the vent arch to the chimney anchor plate. My chimney is a two-walled stainless steel flue pipe, open to free air and not surrounded by brick. It draws well year-round and with the lighter weight the arch did not require buttressing.

For a 900mm or ~30" diameter oven, I'd think a 6" inside diameter chimney pipe and anchor plate would size up better than an 8" pipe. Others will correct if I'm mistaken. I simply flared the underside of the bricks at the vent, my chimney draws quite nicely. After years of fires I have no soot stains on the face of my oven.

Can't help with local sourcing. Good luck with the build, and welcome to the forum!

[yoboseyo]

Progress update:
i have completed the base and cutting bricks for the inner arch
I will look to cut the hearth bricks next

[UtahBeehiver]

Need to consider weep holes in the hearth before the start the floor part of the project. I would drill from the bottom since the concrete will most likely blow out, then silicon some window mesh over the holes to keep the bugs from building nest. Weep holes allow moisture to egress out from the hearth area, wet insulation is one of the main reason for poor oven performance. Many builders are also place scrap or cheap ceramic tiles on the hearth in conjunction with the weep holes, this raises the CaSi board of the hearth leaving channels for water to migrate to the weep holes. Now is the time to do these suggestions.

[yoboseyo]

Need to consider weep holes in the hearth before the start the floor part of the project. I would drill from the bottom since the concrete will most likely blow out, then silicon some window mesh over the holes to keep the bugs from building nest. Weep holes allow moisture to egress out from the hearth area, wet insulation is one of the main reason for poor oven performance. Many builders are also place scrap or cheap ceramic tiles on the hearth in conjunction with the weep holes, this raises the CaSi board of the hearth leaving channels for water to migrate to the weep holes. Now is the time to do these suggestions.

Thanks, I hadn't considered that. Just to understand properly, how exactly would water get in once the whole thing is rendered over?

How big should the weep holes be? If I make them 1/2", will that blow out?

[JRPizza]

I can't tell if you are planning a roof, but if water is allowed to hit your stand, it is likely some will eventually get under the floor and potentially soak your insulation.. Raising the insulation up with tiles and/or drilling weep holes will help mitigate the effects of moisture ingression if it does happen. I did not do either, and although I put up a roof I still managed to soak my insulation boards during the build. It took me several fires to drive the water out and it had to come out through micro-gaps where the render met the hearth. Weep holes would have made the drying much easier.

[UtahBeehiver]

Plus one on JR's comments. 1/2" will still blow out so drill from the bottom of the hearth upward. CaSi can readily absorb water and as mention before, wet insulation is one of the major reason for poor oven performance.

[david s]

You probably won’t know where the steel reinforcing is, so use a small pilot hole, say 1/4”. Which will allow a new hole location if you strike steel as well as reduce the blowing out. It can actually be an advantage because the divot left will create better drainage to each hole. Once pilot holes are drilled you can increase their size to 1/2”.

[NewEnglandNewb]

yonosey, if you would like to see an example of weep holes through the hearth and tile to raise the insulation to give the water a path to escape, page two of my build thread shows how I did it. Link -> https://community.fornobravo.com/for...e-island/page2

[yoboseyo]

I drilled the weep holes and raised the CaSi board with some tiles. I was a bit concerned with the lack of structural integrity of CaSi. I ended up putting the tiles about twice as dense as pictured.

Cutting the floor brick, I forgot to lay it at an angle. I figure it'll be fairly flat on the CaSi, and if not I can run a belt sander over the hard edges.

About the mortar - what's the recipe? 3:1:1 sand:fireclay:fondue? These I can get - already have the fondue

[yoboseyo]

Finished cutting the floor brick.

Should be able to get the dome going this weekend.

Called up the supplier for instructions regarding my Ciment Fondu - they said to mix it with only 3:1 sand and nothing else.

Anyone have a good recipe for castable with Ciment Fondu?

[yoboseyo]

Started the masonry work.

I used 3:1:1 sand:fireclay:fondue. I had tested a mix without the fireclay and it was slightly harder to work but the result seemed the same. Both mixes are a lot harder to work than regular mortar.

The inner arch has been the most difficult thing so far, and I wasn't able to get the arch bricks completely evenly spaced and the bottom of the bricks are not perfectly lined up against each other

[yoboseyo]

I screwed up the dome a few courses up by not using the IT because I thought I didn't need it. A compounding of a small error meant that the dome was going to be lower.

I could either correct it, leaving an unsightly shape in the interior, or roll with it. I decided to roll with it, but with the slightly lower dome, I would need a lower opening. I compensated for this by spreading a layer of sand to raise the floor bricks.

In this time, at least I took the opportunity to correct the orientation of the floor bricks into a herringbone pattern. Crisis averted for now, but the masonry work could've been cleaner





Didn't have anything round for the top layer so I made this out of cardboard


Completed dome with raised floor brick (metal strip to temporarily keep the sand in)

[yoboseyo]

Question:
I know compressing blanket insulation reduces its R value, but say if a 2" blanket was compressed to 1", would that insulate better or worse than a 1" blanket?

I'm a bit concerned that I compressed the insulation too much by overhandling it. I only had 2 rolls of insulation (7.2m*1") and while I got 3 layers , I used a lot of offcuts to fill the gaps, and I wound the chicken wire quite tight.



Then for the perlcrete layer, I'm intending to use 1". I didn't use anything to measure the thickness. I thought that 1" is not very thick so I should be able to make it a uniform thickness just by laying it from the base up. Not the case.

Ended up making a cutout to hopefully correct the roundness in the next layer.


It's makeshift, but it seems to work.


Left a hole to fit a vent



This is where it's at now. Going to focus on the decorative bricks for the base, as the outer arch will be laid atop of that. The flue will sit between the inner and outer arches )(I left some space where it will go).

I have not decided how I'm going to build the flue. I will share my ideas and will have some questions.

[yoboseyo]

Putting my lovely collection of Canberra reds to good use