Challenges and progress of building pizza oven on a slope

[terratree]

Great idea !!

This would allow a fairly quick course, I imagine ?

Nice work.

[Yokosuka dweller]

And some more pics here - including from the finished dome with the wooden floor brick removed. Feels real good to be through this stage of the build. But when I look into the oven I remember each crooked brick.

[Yokosuka dweller]

Weather was nice this weekend so managed to cut and lay the last course and grind a plug. I didn't have a jack-lift and didnt want to buy a yogaball or a load of sand to fill into the oven so I devised another system, which I think can be my contribution to this community. I used a long nut and created a support system wherein the last course would be held up sitting on a circular piece of wood below, but which was held up with a lift system from the top. I then created two circular pieces of wood to ensure the last course would accommodate the funnel-shaped plug. It worked surprisingly well actually.

[Yokosuka dweller]

9th course now set. I could either mortar two bricks together and cut a larger plug now or tailor another course of small bricks with a smaller plug. I removed the IT, which has been essential really, and while the 9th course was difficult and bricks succumbed to gravity 3 times, I finally managed. It's not entirely symmetric, due to my cuts and my desire to use as many leftover bricks as possible to minimize waste. I also notice two flaws in this 9th course - namely that I have two instances where seams overlap. I couldn't see from the inside when placing them, so that's why it happened. But I gather that this is so close to the top of the dome that any crack cannot go vey far until it meets a juncture. So should be no issue.

Next I will do as others have done and recommended which is to scribe the outline of this remaining hole onto a piece of cardboard, and then divide into sections for bricks, as well as a round plug in the middle.

My idea is to cut those pieces from sleepers/horizontal brick pieces. That way I will have an inner plug that's too thin but which maybe easier to fiddle and fit into the confined space. Then, once that has set, my idea is to take as many remaining larger brick wedges / leftovers and place them on the top and then pour a very liquid homebrew mix over it and allow to set. But first need to see the scribed outline and see how difficult it will be to grind the last weird shapes.

[Yokosuka dweller]

8th course finished. Still working with the indispensable tool. But it's taking time to place the bricks now, partly because the mortar needs to set around each brick for a few minutes before I dare to remove the tool, and also - I decided to tailor-cut each brick to reduce or eliminate mortar gaps. This means I can only mix small batches of mortar. But since this is a hobby and not a job I'm enjoying it even it's a bit slow.

I think I may have only 1 or max two courses left before plugging this thing. Have to start thinking about what shape of plug makes sense, and how I would place it.

[Yokosuka dweller]

Thank you very much, these are indeed things I also need to take into consideration. I am planning for a heat break on the floor as well as around the inner arch. So your point is right, I need to dedicate enough additional brick to cover the overhang between the arches, like in the primitive sketch here. I think this is pretty much a copy from your build - which makes sense, since I keep returning to the build threads or your build, Utah's and Sharkey's to get info and inspirations for next steps.





As for chimney adapter plate - I haven't decided yet but you're right it would be helpful to decide this before building the vent area. I think optically a mason/brick chimney looks better than a SS pipe. But weight is a factor, as is stability. If for example, I do not mortar the outer arches onto the floor, then building a masonry chimney would make the thing pretty top heavy. We have earth quakes here semi-regularly, maybe the thing would topple over. Similar to the states, I think in Japan a 1000mm double walled pipe is around 200 USD, then one would have to add adapter plate and chimney top/hat to that budget, which would run it up to 4-500 USD. But yea, these are some considerations.

[JRPizza]

The other thing you should do before you proceed is figure out if you are going to use the adapter plate that is meant for the type of pipe you choose (assuming you are using a metal chimney pipe). The dimensions of the plate will help you figure out how to transition from the opening in your vent arch to the pipe. I was able to find dimensions of my adapter prior to buying it so I could do some preliminary sizing. You will be able to determine if you can use a standard adapter or if you need to do something custom such as casting a transition or doing some sheet metal work.

[JRPizza]

Have you decided if you are going to build in a heat break? I think they are a good idea, but many ovens have been built without them. If you don't incorporate one, you can brace your aft vent arch on top of your inner arch and gain some strength, potentially allowing for narrower bricks. I didn't want to do that and wanted to keep the landing short(ish), so used the overhang to give some additional strength and fore/aft stability to that portion of the arch. You have a bit of inner arch projecting from your dome, so you might be able to increase the amount of overhang if you chose to decrease the width of the lower portion of the bricks.

[Yokosuka dweller]

Thank you JR for sharing the diagram which I can understand. So you were using half brick width in aft arch which I'd do but that would mean 1,5" longer vent area. I'm not sure yet, whether I am going to go for 3" there or increase to 4,5 with the overhang on the inner arch. But I think I will go with the 3" forward arch just to keep the entry area relatively short. That would also be the most economical in terms of using 1/3rd bricks I guess, but the other day I went up into the backyard and managed to find another 10 really old SK32 firebricks which my wife's grandfather had used for something up there, way back when, so my brick budget has just increased and I'm grateful for that. Anyways, we have stormy and rainy (and snowy perhaps) weather here at the moment and the oven is covered and dry, so I won't be rushing ahead with this in any case.

[JRPizza]

I can't remember if I posted all my dimensions, but the picture below shows how my aft vent arch bricks were effectively 3.5 "wide" with an additional 1" extension to overhang the oven arch, and although not shown my forward arch bricks were 3" wide. I don't know how much thinner you could go and still support the weight of the bricks that will go above the arch.

[Yokosuka dweller]

Now that the dome is soon closed off for good, I've started to look into inner/outer arch flue and that part of the build. I really like what JRPizza and Sharkey did which is this 's-shaped' flue design/serpentine and will probably try to see if I can emulate based on those builds. But I am not yet confident on the dimensions of the flue area.

My oven dome is around 32". For that I've read between 32-26" size that a 6" flue will work. Then I've also read that a flue exit into the chimney should be around 50 square inches. So that would mean I need to anticipate a 6" deep/8" wide end point of the serpentine, at least that would get me to 48 square inches, and just about enough. I haven't decided if a double wallet chimney is necessary or I can use single SS chimney. My father in law has single wall SS chimney lying around which I am welcome to use, but I am thinking that single walled carries a risk of cracking the chimney base due to heat expansion?

Another issue I need to figure out is the depth of the flue/entry area. Since my dome will be about 32", would it be enough if I used 4/3 firebrick? I would use 1/3rd as link to the inner arch with fire rope and refractory sealer cutting notches into the brick and placing those on top of the inner arch it like JRPizza did. If I did that, then it would give me 2/3rd bricks as middle area of the flue arch (about the planned 6 inches) to move upwards and turn into serpentine, and then a last 3rd - about 3 inches for the outer arch ring. Does this make sense, and would this be deep enough and strong enough to accommodate the chimney? Especially, would a 3 inch brick arch be strong enough? I can't see from the photos how large the brick pieces others have used were.

I may post this in another subforum as well since I'm not generating much traffic in here.

[Yokosuka dweller]

Finished 7th course, mostly half bricks but having to cut off wedges of the vertical edges more now to keep the 'inverted v' to a minimum. Pretty easy this course and I am roughly back to round shape, but I expect next course which will be almost vertical to be difficult, as the bricks will want to slide off position.

Also, can see that horizontal mortar gap between the courses will increase, maybe now is the time to start beveling the bottom of the bricks to minimize that gap?

Anyway, I ran out of cement and am almost out of bricks, so need to do a run to the hardware store first before anything else.

[Yokosuka dweller]

After being away for work for a week and then back to rainy days, I finally found time to close the arch. I had a bit of a 'dreaded droop' case to accommodate. I used a stick affixed to the indispensable tool to keep the course at the correct height all the way round. In front of the arch I had as much as half inch droop to sort out. For sure mortar was my friend as were strange cuts to accommodate as much brick as possible and get back to desired height and circular shape. It worked, but for sure I won't win a beauty contest. Now I'm just hoping that it will be strong enough to take firing.


If I were to do this again, I would much earlier have started to use a height gauge to ensure I won't gradually drop height as I get close to the arch. I was warned by the old-timers on here and thought I'd be able to prevent it. Lo and behold, it happened. Good experience!

I assume things will get a bit easier the next couple of rows. But now I guess I have to start using 1/3rd brick cuts to minimize horizontal mortar gaps between the bricks? Well, I got my saw and will cross that bridge also.

[Yokosuka dweller]

The flue area is too hot for Granite. The radiant heat will cause the Granite to break. It would be okay for the landing though.

Okay, that's a shame. Granite would look very nice in that area which anyway gets sooted and dirty from cooking action. I will talk to local stone mason to see what they recommend, and otherwise go with firebricks till landing area.

Arch now set! Feels good to have that step done. But I also know next step to fit dome bricks into my poorly cut arch transitions will be a tricky affair and I will need to find the right time, a day when wife and kids are out the house and I don't have any work to do, then I can focus on 6th and 7h courses, which likely will be the ones where the arch/dome transition will take place. I see some builders have their arch/dome transition in the 6th course (above ground), such as Utah, but others in 7th course, I guess it doesn't matter does it?

[UtahBeehiver]

The flue area is too hot for Granite. The radiant heat will cause the Granite to break. It would be okay for the landing though.