36" Pompeii low-dome in Livermore, CA

[Larry P]

After about a year of planning, I've started building my oven. My plan was originally for a 42" oven with an elliptical dome, but I decided to back it down to 36" after cooking in a couple ovens, one was a 32" or something like that and pretty nice, another was a FGM950B where the owner was disillusioned with the heat-up time and was thinking about switching to something smaller. So now I'm going for a 36" floor, 14.5" elliptical dome, 9" soldier course, and 9" radius semicircle entry.

My wife and I are vegetarian, plus some fish, and we're very serious about pizza, so I'm more concerned with an oven optimized for pizza and bread, and couldn't care less about stuffing a turkey in there. So the low dome.

The end goal is to have an igloo-style oven with a tile mosaic finish.

[Larry P]

I poured the slab between Christmas and New Year, with a canopy to help protect me from El Nino

[Larry P]

Stacking the blocks... I had originally planned to do 5 layers of block, but decided 4 was enough and stopped there. Then the rains claimed my canopy.

[Larry P]

My wife voiced some concerns about the deep corner, more useful as a raccoon condo than for wood storage, so I used some of my leftover blocks from the 5th course to build a wall across the back:

[Larry P]

Poured the upper slab last weekend, and this is how she sits today.

Moving forward, I plan to source firebricks and mortar locally, and have already bought insulation from Forno Bravo. The blankets were delivered overnight by FedEx ground, but boards are on backorder for a couple weeks, which works ok since I have commitments for the next few weekends.

I'm still deciding how I want to do my entry, and how I want to buttress the soldier course.

[JRPizza]

Looking good Larry! Looks a lot like my corner build, except mine is slightly larger than yours to accommodate a 39" oven. I too only used 4 layers of cinderblock, but have 5" of insulation under my floor to raise up the oven a little bit. How much insulation are you planning on using?

[Larry P]

Thanks for the comment and good question. One thing I have disliked about some other ovens I've used, is having to bend over too much to watch/turn the pizza, which is why I was going to do 5 courses of cinder block, to raise up the hearth. Setting the 5th block up there made me realize it was way too high. Now I think I'm caught in-between too low and too high, and it has occurred to me that an additional insulation layer would help.

So for now I have enough ceramic fiber board coming from FB to do 2" insulation. As I keep reading and mulling things over, I'm considering an additional 2" of CF board, but I'm also worried about relying on gravity too much in an area where lateral forces may be applied to the oven, so I'm also thinking about doing a 4" layer of vermicrete or pearlcrete.

[UtahBeehiver]

IMHO, 2" of CF board is the bare minimum.floor insulation. The additional floor insulation will allow you to better utilize residual heat and also get you to the floor height you are concerned about.

[RandyJ]

If you can afford to get the extra 2" of ceramic board then that is going to be your best course of action. If you are wanting to go a little higher then you can do what I did and put a layer of patio pavers on top of the stand. This also acts as a drainage path so water does not sit in the insulation. As for gravity holding it down in a earth quake I don't know what else you would do. You don't want the dome bricks to touch any thing else but insulation. As some of the others have said it also looks a lot like my corner build as well.

Randy

[Larry P]

Thanks guys. Cost isn't much of an issue, but I'm more worried about having insulation stacked that high. Maybe 4" of perlcrete or vermicrete to raise the entire deck? What are the disadvantages of that compared to more CF b oard? (besides it being more work).

[deejayoh]

CF is much better insulator than perl/vermicrete. Something like 4:1. So adding 4 inches is about the same as an extra inch of CF board. Plenty of builds here are built that way.

There are quite a few threads on oven floor height. Do a search to see what you can find. I think the general recommendation is elbow height. My $0.02 is that the advantage of a higher oven is not leaning over to check your fire or your food!

[RandyJ]

I would agree. Also the cf board is not a very slippery material. I don't see it sliding on its self. If yo were worried yoy could poor some concrete barriers around it to help hold in place., but my thought is that unless you buttress the sides very well with a low profile dome the sides will fold before you have a problem with the insulation moving around. With that said the better insulation value of the cf board makes a way better choice. There is plenty of work to do so not doing the vermicreete is a big help. If you want it higher either poor a second layer of concrete or add a laver of patio stones to get to the spot you want.

Randy

[Larry P]

Ok thanks, I'm convinced on a 2nd layer of CF board. I'll place the order today.

[Larry P]

On the subject of floor height, it turns out that the "tip of the elbow with forearm parallel to the ground" test, means 4" of insulation puts my deck at the perfect height for me. I've ordered more insulating board, and hopefully it's in next week.

In the mean time, I purchased my HC Muddox fire bricks and went probably about as far as I could cutting bricks, while I wait for the board:

[Larry P]

Built my template for the elliptical dome profile, which I'll use to form my sand dome, then cut upper corner bricks. I think this is legitimately as far as I can go until I have my FB board: