36" build in heart of Europe, Czech Republic

[mrotter]

JRPizza Doing one row with wider bricks prove to be good way. I picked some speed and was able to finish last course today (no mortar between bricks yet). Hole for keystone has about 11 cm diameter, so I believe I will have to go with 2-piece keystone.

Question is, is it better to make those pieces stacked horizontally or vertically? I believe horizontal (side-by-side) keystones will be easier to cut and place.

Another bad message for me is that my 3rd bag of mortar is almost empty and I will have to likely buy a new one - either 5 or 25 kg.

[mrotter]

When trying to make the shortest vent possible there are two controlling factors - providing sufficient area to exhaust gasses and feed your chimney, and if using brick enough depth to build a stiff/durable structure. If you cast a vent you can make it pretty short and only worry about feeding the chimney. If you are using brick the "standard" seems to be 1 1/2 bricks deep. My vent is free standing, meaning I have a heat break between it and the oven dome and it gets no support from the dome. I also used L shaped bricks at the rear of the arch that went back over the top of my dome arch that gave me (I thought) a little more stability and area for the mortar to bond to. I don't know what the absolute minimum with brick would be and it probably depends on how stable the base of the arch is (mine sits on CF board), whether you tie the vent back into the dome structurally, and how much load (weight and potential for movement) your chimney structure puts on it.
Building a vent that is too deep can make getting food in and out of the oven more difficult but many do fine with the brick and a half depth (~13.5"). If you have that much room (10 cm?) to the end of your hearth slab why wouldn't you want to bring the arch our closer to the edge?
Also, I can't remember if you are going with the recommended 6" minimum chimney diameter?

Yes, I plan to go with 6" chimney ID, that's about standard for these types of structures.

Yes, 1.5 brick depth is about standard as I also noticed on many albums. Main thing that bothers me is really easy of access inside the oven. My arch will also be free standing and separated from dome arch by fire-resistant rope + heatbrake in the floor (air gap). I also plan to use those L-cuts.

I just did not want to make entry arch unnecessarily deep. Some kind of minimal landing would be great. I will do measurements asap and will report back.

Also, I started penultimate dome course yesterday, as per your example -> 12 cm wide half bricks -> pockets filled with scraps/mortar. Seems to work just fine.

[JRPizza]

When trying to make the shortest vent possible there are two controlling factors - providing sufficient area to exhaust gasses and feed your chimney, and if using brick enough depth to build a stiff/durable structure. If you cast a vent you can make it pretty short and only worry about feeding the chimney. If you are using brick the "standard" seems to be 1 1/2 bricks deep. My vent is free standing, meaning I have a heat break between it and the oven dome and it gets no support from the dome. I also used L shaped bricks at the rear of the arch that went back over the top of my dome arch that gave me (I thought) a little more stability and area for the mortar to bond to. I don't know what the absolute minimum with brick would be and it probably depends on how stable the base of the arch is (mine sits on CF board), whether you tie the vent back into the dome structurally, and how much load (weight and potential for movement) your chimney structure puts on it.
Building a vent that is too deep can make getting food in and out of the oven more difficult but many do fine with the brick and a half depth (~13.5"). If you have that much room (10 cm?) to the end of your hearth slab why wouldn't you want to bring the arch our closer to the edge?
Also, I can't remember if you are going with the recommended 6" minimum chimney diameter?

[mrotter]

JRPizza

Also I have a question related to "depth" of vent arch. I have around 35 cm to work with but would like to make vent arch rather shallow - 25 cm deep (one brick on longer side). I planned to make entry hole for chimney 8 cm deep and (around) 20 cm wide.

So that will be 8 cm (hole) + 8.5 cm of brick on each side of hole. Do you think its just okay? From some albums I saw quite deeper vent arches.

[mrotter]

I didn't bother me at the time as it was not on my radar, but now that you mention it they are rather large gaps. Even though I suggested going with half bricks if you want to minimize mortar exposure to direct flame staying smaller is probably the better choice.
What did bother me (and you can see it in the picture) was when I was "gently tapping" my keystone plug into place I knocked some shallow "chips" from the adjacent bricks. If I was to build again I would make sure I had a little more clearance when inserting the plug and let the mortar help locate it at the proper height vs trying to have interference do the job.

OK, I decided to go with wider bricks for next course and fill the "pockets" with brick scraps. Given that I am two rows away from keystone, structurally, it is just fine and should hold up just well. However the "pocket" problem will transfer to next-next row as well and will be even more pronounced, so I will cut small triangle shapes to fill those spaces. Then there will be just enough room for keystone, which will likely have to consist of at least two parts, I will see when I get there (maybe around weekend).

Also, now I have like 10 bricks left so not enough to make vent arch and chimney structures. Now, I need some design ideas as I have to decided whether vent arch bricks will be visible from outside or covered with some final surface solution (broken tiles, silicone/acrylic render, whatever). If they won't be visible I can use reclaimed almost free bricks. If visible, would have to buy new (not that bad, as only limited amount will be needed).

[mrotter]

I didn't bother me at the time as it was not on my radar, but now that you mention it they are rather large gaps. Even though I suggested going with half bricks if you want to minimize mortar exposure to direct flame staying smaller is probably the better choice.
What did bother me (and you can see it in the picture) was when I was "gently tapping" my keystone plug into place I knocked some shallow "chips" from the adjacent bricks. If I was to build again I would make sure I had a little more clearance when inserting the plug and let the mortar help locate it at the proper height vs trying to have interference do the job.

I will check how big those pockets actually are on my build and if they will be "manageable", I will fill them with firebrick scraps as well as I could. If they will be huge, I will likely have to make those smaller cuts.

[JRPizza]

I didn't bother me at the time as it was not on my radar, but now that you mention it they are rather large gaps. Even though I suggested going with half bricks if you want to minimize mortar exposure to direct flame staying smaller is probably the better choice.
What did bother me (and you can see it in the picture) was when I was "gently tapping" my keystone plug into place I knocked some shallow "chips" from the adjacent bricks. If I was to build again I would make sure I had a little more clearance when inserting the plug and let the mortar help locate it at the proper height vs trying to have interference do the job.

[mrotter]

Looks great! I remember my father-in-law eating some of the first pizza and saying how great it was but he was never really sure I'd finish it till I did ;-).

When I got to where I could get 4 pieces out of a brick I went back to using half bricks for a row or so and it saved me some cutting.

Yes, I could do that now as I am now exactly in the course where I could split one brick into four pieces and use those, but I think it would introduce "mortar pockets" under those wider bricks.

Right now top side of my last course has bricks about 6 cm wide, bottom side about 7 cm (give or take). I could use half-brick (like on lower courses) = 12 cm, which would work exactly like your picture with one exception - I think that there would be big "mortar pockets" under those wider bricks visible from inside of the oven, something similar like inverted V but horizontally. I even see those on your picture - did that bother you? I think about it seriously as it would speed up the process considerably. Also, note that my oven has smaller ID (35-36") so the "horizontal V" is even more pronounced. On your picture I see 13 half bricks in that course, in my oven it seems I would need exactly 10 half-bricks.

See pic with red areas.

[JRPizza]

Looks great! I remember my father-in-law eating some of the first pizza and saying how great it was but he was never really sure I'd finish it till I did ;-).

When I got to where I could get 4 pieces out of a brick I went back to using half bricks for a row or so and it saved me some cutting.

[mrotter]

While you're not quite closed at the top, you can use this access to filling joints on the inside of the oven. It is far easier than trying to do it from the entry.

Damn, you are right. I almost forgot. Will do that today. I did some of bigger air pockets days ago, but certainly missed some spots. OK.

[david s]

While you're not quite closed at the top, you can use this access to filling joints on the inside of the oven. It is far easier than trying to do it from the entry.

[mrotter]

More photos.

[mrotter]

Photos. 9th course is basically complete, I cleaned inner side of dome with wire "cleaner" a bit, also leveled the floor bit more. At this point it is fair to say that mortar is giving great job. Initial adhesion of the brick is helping quite a lot, but still I have to support bricks with wooden sticks, at least like for 10-20 minutes.

Also, bricks are getting narrower and narrower, I cut bricks into thirds (about 7 cm wide), next course from rought measurement I made it seems I will be able to cut each brick into fourths, each about 5.5 cm wide to achieve proper brick staggering.

I will upload more photos below.

Also, it seems i relatively managed to avoid droop. I made some compensations and also made length adjustments to IT as I was aware that my pivot point was bit above the floor (like 1" at max), so I am checking my IT length before each course and make it few milimeters shorter.

Please, guys, if you see any problems or have recommendations, let me know. It seems that two more regular courses and then final keystone. What encourages me is that my father in law thought that I would not even be able to reach the phase I am in and also neighbours seem to ve quite interested in the WFO.

JRPizza
UtahBeehiver
david s

and other. Thanks for your assistance.

[mrotter]

In my builds the gap (around 8mm) acts as an expansion joint as well as eliminating heat flow by conduction. It allows the inner oven castings to expand freely without putting stress on the outer decorative arch. I've seen enough ovens with cracked outer arches to know that this is a good innovation. I fill the gap with thin slices of blanket, sealed off at the top with som 6:1 vermicrete.

Thanks, I plan about the same gap. Will have to buy rope to fill it.

[mrotter]

Btw, I had 150 firebricks at the start, about 35 remaining, it seems it will be enough (except vent arch where I plan to buy new bricks for better view).

Also, I had 75 kg of mortar mix, now about 30 kg remains, that should be more than enough.