Mongo's 42" CT Build

[david s]

Be aware that thorough sealing both under and over the oven also prevents the escape of water. Moisture in the dome is therefore better driven out before sealing over it. In addition some weep holes in the supporting slab into the underfloor insulation can help remove moisture build up. As well as some kind of vent to allow moisture and steam pressure to be released from the dome insulation. I find it better to drive out the moisture of a new oven after insulating, but before rendering the outer shell.

[shanxk8]

Thanks for the responses Mongo. I unfortunately missed learning about the recommended Redgard underneath the insulation (p/vcrete in my case), so i have no RedGard on my slab to seal. Also, I have my countertops (granite) installed already, and applied my first 2 layers of stucco right down to the granite.

So i guess I will need to come up with a creative way to seal that joint between granite & stucco. (It may just be applying the Flex-Crete the to granite, then a bead of silicone)

[mongota]

Be aware that thorough sealing both under and over the oven also prevents the escape of water. Moisture in the dome is therefore better driven out before sealing over it. In addition some weep holes in the supporting slab into the underfloor insulation can help remove moisture build up. As well as some kind of vent to allow moisture and steam pressure to be released from the dome insulation. I find it better to drive out the moisture of a new oven after insulating, but before rendering the outer shell.

Always good to plan an escape path.

Thoroseal is vapor permeable.

There's also a vent nipple at the apex of the dome.

Drying fires? Oh yeah, I've had a few, lol.

[mongota]

Been cooking up a storm with the WFO this year, it's just terrific as a cooker.

I've had a HUGE distraction this year, been working on a seating area down by the water. Had to be hand dug due to wetlands restrictions and there was a bit of time pressure with a non-extendable permit deadline that expired this fall. So after hauling out about 50 yards of earth in drywall buckets and bringing in about 16 tons of stone for the walls and another 250sqft of bluestone for the seating surface, it's done. Well, it's done except for finishing the stairs. Going to use stone for the stair risers and bluestone for the stair treads. There's always one more thing, eh? Or in this case, eleven steps, so eleven more things?

[mongota]

Started the stone veneer for the base of the oven. All this is stone from my property. Working in between, and right through, the rain showers. I don't mind cold. I don't mind wet. But wet and cold, when mortaring stone? Meh. lol

I dry fit them first, them mark them with a soapstone marker for orientation. That way if I have to pull and reset, of if they simply fall down since they are only dry set, it makes it easier on me to get them back in their proper places. After I get a bunch in place, I'll mix up a batch of mortar and get to work.

[mongota]

And...
-Finished one large side, fully mortared.
-The other large side, 3/4ths of it is mortared, the top course on the left and the top two courses on the right are dry fit, they need to be mortared. You can see some firebrick shims holding things together.
-And the front of the oven, the left side is mortared, the right side is dry fit and needs mortar.

Tomorrow is supposed to be dry ans sunny, mid-50s temp. Good weather to finish it off.

[JRPizza]

Mongo, I love the look of the natural rock. Using materials from your property is a special bonus.

[mongota]

Appreciate the kind words JR.

Stone is one thing I have plenty of around here. lol

[MarkDLxu]

This was my method for figuring out the cut lines for the dome arch bricks. This was confusing to me until I started building the dome, once I saw it with my eyes it became so very simple.

The red line in the drawing represents a line radiating from the center of the dome floor, essentially, the IT. I used my IT to get my cut points, but a string anchored to the center of the floor would suffice as well.

The yellow dot represents the inside radius of my brick dome, for a 42" oven, that'd be 21" from floor center.

The blue dot shows where the bottom of the arch brick meets the inside face of the plywood arch form. That may also be 21" from center, or it may be slightly different. It depends on where you place your arch form and the geometry of your oven opening.

The orange dot represents the outside diameter of the brick dome, for my 42" oven that would be 21" + 4-1/2" thick brick = 25-1/2".

The basics of the layout? With the brick in its proper place on the arch template form, position the IT (or string) next to the side of the brick so that the outside diameter marking (orange dot) on the IT or string intersects the top edge of the brick. Holding it steady, mark the location of the orange dot, and on the side face of the brick, mark the inside diameter of the dome (yellow dot). You can now set the IT or string aside. Mark the blue dot on the underside of the brick where the bottom edge of the brick meets the inside top edge of the arch template form. You'll connect the orange dot to the yellow dot, and the yellow dot to the blue dot. Those are your cut lines. Because the geometry of the dome/arch intersection changes a bit as you higher up the arch, you can mark both sides of the brick and adjust your cuts as needed.

I built my arch from the left and right feet of the arch, simultaneously moving upward, meeting at the keystone brick at top dead center.

Prior to cutting any brick, I placed my arch bricks on the arch form, shimming them in place. I chose to not taper them. I aligned the outside edge of each arch brick with the outside face of the plywood arch template. With the template being plumb, that'll assure the face of your arch is plumb. The bricks will overhang the arch template, projecting inside of the dome. With the arch bricks shimmed in place, mark on the outside face of the arch template where the left and right edges of each brick sit on the arch form. You'll be taking the bricks off and replacing them, the marks assure that when you replace them you'll keep your planned pattern, spacing, and layout, and when mortaring them you'll prevent mortar joint creep. Number the bricks so you get them back in their correct spots. I numbered them L1, L2, etc, for the left side of the arch, and R1, R2 for the right side.

I used the IT as shown in the photo to get the cut points on my L1 base brick. I connected the dots, cut the brick, and mortared it in place. I then shimmed my second L2 brick in its place. I transferred the cut edges of the already mortared L1 brick to the adjacent side of the L2 brick, and used my IT (or anchored string should you prefer) to indicate the orange, yellow and blue dots on the "upper side" of the L2 brick. Connect the dots, skewing the lines as needed. Make the cuts. Mortar L2 in place, paying attention to your layout lines on the arch template, and move on to L3.

You can cut and dry shim them all first, then mortar them later in a single batch. Or cut and mortar one at a time. Either way is fine. Just stay on your layout lines.

Thanks for the detailed explanation , tomorrow morning I’ll do it !

[mongota]

Thanks for the detailed explanation , tomorrow morning I’ll do it !

Your welcome, Mark.
And thanks for posting, the notification brought me back to this thread, I never finished posting the build pics! lol

[MarkDLxu]

Upload some pictures, I’m curious to see the final masterpiece

[mongota]

I'm baaaaaack. lol

It appears that I sort of fell off the face of the forno bravo earth for a while. I've been sourcing my photos so I can post the remainder of my build. Bit by bit!

Anyhow, I left off with the dome complete; insulated, stuccoed, and waterproofed. Now for some finishing details.

I used stone from my property to add a stone veneer over the dome. I picked ones that were roughly 2-3" thick. I sort of struggle with stone work...I think it looks great, then I think it looks lousy and I want to demo it and start over. Then I have a beer and it looks fine again. Anyhow...I'd dry fit some stone, then mix up a bag of mortar, then set them wet.

IF these pics properly post, I'll add more tomorrow...

[SableSprings]

Welcome back from the brink... I'm completely sober (although it is after 5, I'll have to fix that after this post), and I think your stone work is looking fabulous. It's going to be a slow process to get the "best" fit, but it certainly will be worth the time based on what I see now. Your pictures posted just fine, so we'll all be looking forward to the next pics!

[Chach]

That stone work looks great so far. Stop second guessing yourself and go with it. We all critique our own work almost too much...you will know when something doesn't sit right and bothers you...most times the stone work looms kind of funky when your doing it but once you get to a certain point it starts to tie together. You have a very creative look going on and I am eager to see your finished oven.

Ricky

[Chris inPA]

Is your arch entirely of fire bricks? Or, did you use regular bricks for the end?