Pdx 42" update

[mongota]

By the why - is there a trick for estimating how many fire bricks I'll need to complete the high-dome oven?

Interior diameter of 42 inches. And bricks are 9"x2.5"x4.5".

Macrinehart

I have a 42" oven, I did some rough calculations based on the exterior surface area of the dome divided by the surface area of a half-brick with a bit of fudge factor thrown in for mortar joints on the exterior of the dome. Between that number, then numbers for the floor brick, the landing arch, and chimney transition, adding some in for 'oops' moments, I rounded things off to 275.

I bought a first batch of 224, then went back and bought another 50. So 274 total. I didn't need all of the 50, some of those were for a tandoori oven. Probably used 255-260 in this oven.

I could have been more conservative in some of my cuts, but I just built the thing as I wanted and took what it gave me. Someone could certainly use fewer brick. Or more!

Here's my starting pallet of the original 224, and the offcuts when I was completely done with the oven.

[Macrinehart]

Math is overrated.

[david s]

"For hearth width: 2" wiggle room + .5" stucco + 3" insulation blanket + 4.5" firebrick + 42" oven diameter + 4.5" firebrick + 3" insulation blanket + .5" stucco + 2 inches wiggle room. Total: 52""

Before you race in with those dimensions it is a good idea to draw out a plan. When I add up those layers it comes to 62"wide.

[Macrinehart]

Hail to the Community - I will be framing out my hearth form this weekend and want to be sure I have the proper dimensions for my build.

For hearth depth, back to front: 2" wiggle room + .5" stucco + 3" insulation blanket + 4.5" firebrick + 42" interior Diameter + 2" opening arch + 8" chimney landing + 4.5" deccorative arch + 7.5" oven landing. Total: 74"

For hearth width: 2" wiggle room + .5" stucco + 3" insulation blanket + 4.5" firebrick + 42" oven diameter + 4.5" firebrick + 3" insulation blanket + .5" stucco + 2 inches wiggle room. Total: 62" (corrected)

Thickness: 3.5". JRPizza, noted your comment on angle iron. If I can get away with 3.5" and no angle iron for a 32" span in front, I'll go for the U shape. Also - noted guidance from some on airflow for wood drying and I will turn a block on it's side in the back if that works...

[JRPizza]

You probably don't need angle iron - certainly not in the oven and most likely not in the stand. I didn't use it and many builders don't. If you use a proper amount of rebar in your slab and make it at least 4" you can span quite a gap without further support. I also left my storage area maximized and am glad I did!

[Macrinehart]

Not sure if you poured it yet or not but a regret I have is not leaving the wood storage area completely open. I wish I would have made a U for the base and left the front completely open. Looks good and good luck.

Good news, the angle iron is not yet cut! I wondered about that too. Will take the advice, thanks!

[david s]

For simplicity, cost and labour, my build uses two block piers with the precast supporting slab cantilevering over the front back and sides. This has the advantage of allowing good airflow in the wood storage area ensuring that the wood is dry. I employed a U form in my own home build because the oven is hard up against a wall. This results in a poor airflow and damp wood.

[Chach]

Not sure if you poured it yet or not but a regret I have is not leaving the wood storage area completely open. I wish I would have made a U for the base and left the front completely open. Looks good and good luck.

[JRPizza]

The vent arches and chimney transition required the most thought on my part, as there are some pretty good pictures of the different kinds of chimney transitions, but not a lot of explanation, which is why I tried to go into some detail in my build. I found the notched bricks used in the aft/rear vent arch helped me keep the landing at the depth I wanted it while allowing a somewhat wider brick that I thought would add stability and a place for my rope gasket. If you use a chimney pipe you will need an 8" pipe like I used. and if you have an adapter plate similar to mine you will have to make your bricks into a square at the top. To transition from the rectangular opening at the top of the arches to a square and not cover up my forward vent arch, I needed to build my chimney rearwards (if that makes sense) and the extra protrusion of my dome arch allowed this to happen.

[Macrinehart]

Next revision attached. More eraser marks on this one. Here are the changes:

1. center of opening arch and oven arch are now at the same elevation, 1 x 2.5" rank above oven floor.
2. The setback position for the opening keystone is set in pencil. Feedback welcome!
3. The offset for the opening is drawn in, including suggested Side view of chimney landing.
4. Drawing assumes arches for dome and opening start @ 2nd rank above oven floor. (Prior revision has first rank of oven @ 4.5 inches high relative to the bottom of the floor and with dome starting above. Assuming the floor would be cut to IR of dome).

Welcome any insights - thanks to all for excellent feedback!

[Macrinehart]

Lastly I did not use any bricks standing on edge at the bottom. I found it easier to just lay the first row flat like the balance of the dome bricks and build up. It seemed like it was all more balanced and stable that way.

For the first row in the oven dome, should tops be flush with the oven floor? Or is there a course of flat above the oven floor before the start of the dome?

Thanks!

[MarkJerling]

Awesome! I haven't been on my bike for a while but love the long rides and have done a couple of century rides.

So I have the side view ready and also less confidence in some elements of this drawing. First note two possible inset depths...does either work? If not, what is the guiding design principle?

Second - I'm wondering about the placement of the chimney landing - how far forward or back should it be? I drew in a possible chimney placement aligned just forward of the OR for the oven dome at it's base.

Final note, I'm assuming the oven dome starts with a course of sailors. Basically first course is 4.5 inches high, which clears the oven floor by 2 inches. Also assumes the floor bricks are cut to the IR with first course placed around the perimeter. I understand that for the indispensable tool to work correctly the pivot point needs to be positioned below the top of the first course. Make sense?

Who knew that pizza oven aficionados also like cycling? LOL
I do 3-4 rides a week, usually anywhere between 45 and 75km per ride, but I do do some centuries from time to time.
Road bike only.

[Macrinehart]

Hi JRPizza - Took a look at your build thread and think I have a better understanding now. Will darken linkes for the more "forward" position later and re-post. Also like your serpentine curve into the smoke box and chimney, and takeaway that the smoke box needs ot have enough internal volume to allow exhaust to draft out the chimney without getting "backed up" and going out the front. Do I have that right?

I have plenty of flexibility regarding the hearth dimensions at this point, since it's not even formed yet. What I think I need is to use 9" bricks for the arch to opening transition, and set the chimney landing arch in front with another arch of 9" bricks that have 1.5" wider radius (11.5" IR) to form the reveal. I notice on contributor to your discussion. Notched the back of the chimney landing arch so that it overlapped with the transition arch - I suppose that would support the hemispheric design, as opposed to your serpentine design. I wonder, though, if the notching reduces the depth of the chimney landing, or drives other design considerations for the decorative arch in front of the chimney.

In front of the chimney landing is another "decorative" arch, maybe 4.5" deep? So I'm envisioning 4.5" + 9" from the front of the opening to the reveal, or maybe 4.5" + 8 to 8.5" if I notch the bricks on the back side of the chimney landing. I'l post an updated pick of the template later.

[JRPizza]

Your sketches are coming thru a little faint for me - at least the contrast between the lines and background so it is hard for me to see exactly what you have going on. The TDC brick is going to be the longest brick in the arch and as such will be almost full length, with the remaning bricks getting shorter as you approach the bottom of the arch. Some builders try to draw their arches up with half bricks until they have that aha moment - I can't tell if you have done that or not but it seems like you may have. Here is a pic of my TDC brick where you can see that the rear/aft portion has the oven ID radius on the bottom and an angle corresponding to the approximate angle of the dome brick that will sit on top. When I cut that angles I flattened it a little on the top so there would be room for my mortar wedge. Ignore the line on the upper right as it should not be there.

[JRPizza]

You have a few inches (maybe less) of fore/aft (or in/out) position for your arch. If you are constrained for room on your landing you can move it towards the center of oven so there is no stick out at the top (I would not do it) but some protrusion is good and reducing protrusion makes the interior smaller. I moved my arch forward/out so I had some lip to build my vent arch up and over for my heat break and maximize room inside the oven. It all depends on how big of a landing you want. If you read through that part of my build I tried to reason out placement. There is also some discussion on chimney placement. Have a look and see if that answers any questions. Lastly I did not use any bricks standing on edge at the bottom. I found it easier to just lay the first row flat like the balance of the dome bricks and build up. It seemed like it was all more balanced and stable that way.