36" Pompeii low-dome in Livermore, CA

[SteveB48]

Your oven looks great! I'm hoping to pick up my bricks next weekend. How did you cut the curved edges of your floor brick?

Steve

[Larry P]

HI Steve, thanks! Glad to hear you're getting started. For curves, just went slow using a 10" wet saw, and ground any rough edges with an angle grinder. Mark the curve with a sharpy, pencil will wash right off when the water hits it. Outside curves are much easier than inside curves.

[Larry P]

A slight diversion this weekend, got the garden cleaned up and hit some seedling sales - got around 20 tomato plants, including a dozen or so San Marzanos. Also planted a variety of chile peppers including 2 Calabrian chile plants.

[Larry P]

Back to the oven yesterday: I built a form to pour another 4" of cement, bringing the deck up to the level of the bottom of the oven floor. With 4" insulation, I don't like the look of the oven sitting so high above the deck, so this will raise it up. Then I fixed my "rebar dome" to the slab using 3/8" pipe hangers and used that to form the shape using 1/4" hardware cloth. The hardware cloth did help me get a circle shape for the bottom layers, but I think forming it into a dome shape as it starts to curve upwards, will not be any easier or better than just forming the perlcrete by hand using the rebar as a guide. In fact, I think the hardware cloth is in the way at this point, so I'll probably pull it off to continue upwards.

The perlcrete is 10:1 perlite to portland cement, plus per David's recommendation, a handful of fire clay, then mix the dry ingredients, and add 2 more parts water.

[Larry P]

...and to polish off the weekend, Pizza Margherita:

[JRPizza]

Back to the oven yesterday: I built a form to pour another 4" of cement, bringing the deck up to the level of the bottom of the oven floor. With 4" insulation, I don't like the look of the oven sitting so high above the deck, so this will raise it up.

My oven floor is 5" above my "deck" as you call it, but I got the "you aren't going to make this any higher, are you?" so it is going to stay where it is except for maybe the thickness of some tile or brick splits
I think yours is going to look great, and I'm jealous of both your pizza and your climate that is letting you start your tomatoes and peppers already!

[Larry P]

Let's hope it's not too early. It's was actually pretty cold and windy this weekend. We've stunted our tomatoes in the past by putting them in too early, but May is usually safe. Lori wrapped the garden in plastic I guess to keep the wind off them. The peppers are still in the greenhouse window in the kitchen. We'll wait for the next heatwave to plant those.

I'm already liking the look of the higher stand without even pouring the concrete yet. The proportions just feel right.. Go back to Page 1 you'll see I originally intended 5 layers of block on my stand, but decided it was too tall. This solution looks like a best of both worlds, higher stand with the oven sunk in to just the right height for me.

[Larry P]

My oven floor is 5" above my "deck" as you call it, but I got the "you aren't going to make this any higher, are you?"

I just realized - that's pretty high! My floor is 42" above ground. The top of the slab was 36" (standard counter height) I'm pouring it up to 40".

[Larry P]

I tried to add more perlcrete today, and as I said I would upthread, I removed the 1/4" hardware cloth thinking that would make it easier. Ultimately, I was able to get 1 or 2 grains of perlcrete to stay in place. It was going everywhere but onto my dome. So, I decided to wrap the hardware cloth back around the rebar form, only higher this time, which allowed me to pull it into a smaller radius. That put me back in business, but I think for the steepest part fo the dome, maybe add more portland cement; will that make it stickier?

For now, just moving along, and I figure I'll fix any imperfections in when I render. I don't recommend trying to replicate much of what I did here. This step is all no fun.

[UtahBeehiver]

Larry,

V or P crete is kind of like the "three bears", too cold, too hot, just right. The moons need to line up with the right consistency when working with high ratios but you are getting there.

[Gulf]

.................but I think for the steepest part fo the dome, maybe add more portland cement; will that make it stickier?.............This step is all no fun.

I installed the vcrete in the same manner as the dome brick, working intirely from the bottom up. I started on one side of the entry and installed about a 6" course of vcrete all the way around the dome to the other side of the entry. By time I got back to the original starting point on each course, the vcrete had set up enough to install another course. The steep portions of the dome are no problem when using this method .

Here are some of my vcrete pics.

[Larry P]

Thanks Gulf. I've studied your build quite closely. There's no way that would have worked with my brew. With no external support, it simply falls down no matter how thinly I lay it, which is why I'm considering adding more portland for the next round.

I started filling in the top just to use up my perlcrete. The sides would not have supported me adding any more, but I had a few gallons spare. If you look closely, my rebar frame is just touching my ceramic blankets on the corners, so the top section would have always been a separate pour, and the sides get thinner and thinner as they go up. It's a consequence of trying to fit an elliptical dome inside a hemispherical dome.

[Larry P]

Getting there... I got really frustrated with the perlcrete today, decided to up the mix to 8:1 perlite|portland and add 2 handfuls of fireclay. It helped. It was sticky enough to stand up and be molded. One more day and I think I'm done with this phase. Then it's just to decide how long to let it dry before rendering.

[Larry P]

Well here's another milestone: The perlcrete is finished, and because it envelops the backside of my chimney, I had to ditch the little 2' stove pipe I'd been using and mount the actual chimney, which is 3'x6" dual-wall duravent. This chimney won't fit under my canopy, so now it the weather threatens rain, I suppose I just have to drape a tarp over it.

For the first time, I can see the finished shape of the oven. Now it's just finish work - render and tile the dome, and stonework around the base.

The 6" chimney draws well enough: http://www.youtube.com/watch?v=fHj9HSIas08

[Larry P]

Two weeks after finishing the perlcrete, I rendered the dome last weekend. I was surprised how satisfying this felt. Not only does it look much more round now, but for the first time I feel like it's looking like a finished oven. I still have lots of finish work to do, but this should be waterproof now, and I *could* throw a coat of paint on it can call it done. The render was done with "quickwall" which is a fiberglass reinforced surface bonding cement, to which I added an acrylic fortifier.