42in build in Orange County CA - 2017

[bpal]

Hi all!

I see that I joined the forum back in 2013. I've spent countless hours browsing, reading, bookmarking various build threads. I want to thank all that have contributed and shared their experiences and innovations. I intended to start my build thread as I started, but that was a month ago and here I am. At the end of a long day working on the oven, I'm lucky to take a few pictures.

I'm building a 42" oven. I suppose I chose that size because we didn't really have any space constraints and I wanted something to scale to some of the other features of our landscape/hardscape. Hopefully the large size does not hamper our use of the oven on regular basis.

I'll try to document some of the design decisions that I struggled with the concepts and got past during the build. Certainly there are some areas where you have to get off the computer and paper and start cutting bricks to see how it is going to come together. As of this morning, I'm 10 courses up in the dome, so hoping to get it closed up soon.

[bpal]

I have a contractor that is working on my pool and overall landscape so I worked with him to build out the stand and hearth. I would have taken on this myself but we would have been stepping over each others work so I decided to have him do the stand.

The WFO is incorporated into a full outdoor kitchen. The WFO will be on the right over the double arches and a Kamado grill / smoker will be on the far left side.

[bpal]

For the insulation I went will Thermo-12 Gold with is a CalSil board. I sourced this from Distribution International in Carson. Originally they said they would only sell full boxes but the loading dock guy had a partial box on the pallet and told me it was no problem to buy by the sheet. It came in 12x36", 2" thick sheets. I bought enough to do 4 inches under the floor and enough to insulate a door as well.

The fire brick I bought is Whitacre Greer Buff. I purchased that at Larry's Building Materials in Costa Mesa. I also bought the portland, lime, fire clay and sand there.

[bpal]

I welded up my IT. The pivot point will be about an inch above the floor but I can adjust it as I go to shorten it a bit.
If you use a turnbuckle remember that one end is right handed threads and one end is left handed. Threaded rod won't go into the LH end

This design does leave a little bit of slop at the pivot point but as I've found it actually helps to be able to remove the IT from the placed brick. A simpler IT would work fine... but any excuse to pull out the welder.

[bpal]

I struggled a bit to figure out how and where to position the inner arch. I was aiming for a 19" width and 13.25" height opening. I looked at tons of build threads and photos and went from the computer sketchup model to the brick outside before I could get this straight in my head.

Ultimately what worked for me:
- Find the intersection of the 19" width with the dome bricks. That is the inside position of the inner arch.-
- Decide how much reveal you want on the outside. That is how much outside the dome profile will the arch protrude. I wanted about 1 inch so that determined the depth of the inner arch. I built my arch form to match that profile.
- The bricks that make up the arch will be shorter depth at the bottom than at the top. The brick at the top will match the vertical on the face outside the dome, but need to be longer (deeper) to span the spherical shape of the dome. You use the IT to measure this changing dimension for each brick. The difference is not really all that much from arch bricks at the floor to the arch bricks at the top.

[bpal]

Cutting the arch bricks were some of the toughest cuts so far. I found that wet mortar was the only way to get close to uniform mortar joints. Several bricks I had to take out and re-attempt the proper amount of mortar.

I started each cut with the wet saw and finished up with the hand grinder.

[bpal]

As of last evening I completed the 10th course (or 11th depending on how you count).

For some reason my bricks are not a full 2.5" inches thick. They are closer to 2.25", so I think it will take an extra course. I may only get one day to work on it in the next 2 weeks so it may stall a little bit.

Next I'll have to figure out the thermal break and the building of the vent arch.

Question:
For the thermal break at the floor I am thinking of C-channel stainless steel filled with ceramic fiber rope. I believe others have used this method. I know stainless has less thermal transfer than common steel but certainly it transfers more heat than fire brick. How well has this worked for others?

[UtahBeehiver]

Nice brick work. I used SS rectangular tubing filled with ThermoGold 12 but a C channel should work just as well. You probably have left over CaSi board to fit in but rope will work too.

[david s]

Stainless is less thermally conductive than mild steel, but still some 30 X more conductive than firebrick http://www.engineeringtoolbox.com/th...ity-d_429.html so not a great choice of material if you want it to prevent heat transfer via conduction. If you are going to use it though make it as thin as you can, as the thicker it is the more heat it can transfer. Most of those stainless hollow sections, like table legs etc are pretty thick. A piece you can fabricate yourself from 0.55 mm would be a better option. Apart from reducing heat conduction the primary function of a thermal break is really its ability to act as an expansion joint to reduce pressure from the expanding inner oven parts onto the cooler outer oven structure.A U section rather than a full square or rectangular section, made of thin stuff, may have enough flexibility to act as an expansion joint.

[david s]

As of last evening I completed the 10th course (or 11th depending on how you count).

For some reason my bricks are not a full 2.5" inches thick. They are closer to 2.25", so I think it will take an extra course. I may only get one day to work on it in the next 2 weeks so it may stall a little bit.

Next I'll have to figure out the thermal break and the building of the vent arch.

Question:
For the thermal break at the floor I am thinking of C-channel stainless steel filled with ceramic fiber rope. I believe others have used this method. I know stainless has less thermal transfer than common steel but certainly it transfers more heat than fire brick. How well has this worked for others?

2.25" thick walls for a brick built oven is very thin and you are asking a lot of the mortar joins between bricks. This is why most brick ovens are 4" thick. A second layer of brick or at least/cheaper parging the outside with a 1" layer of home-brew would be a good idea.

[bpal]

The bricks I have are 9x4.5x2.25". So the dome thickness will be half a brick of approximately 4.5" so no problem there. I meant that with my bricks 2.25" thick rather than the apparently normal 2.5", it may take one more course to complete the dome than others.

I'll have to see if there are other options for the thermal break.

I got one more course in yesterday... getting close

[UtahBeehiver]

In addition to the SS tubing I cut the floor bricks butting up against the SS on a shallow angle so there was a minimal surface to surface touch. You could do this as well and eliminated the SS. I believe Dave has also suggested to placed a small v or pcrete joint between the dome and vent floor bricks.

[bpal]

I got close to closing the dome last weekend. I was out of mortar and had company coming over so I had to stop. One more odd shaped wedge and and then the plug. Some of the joints are lined up on this last course but I don't think there is any real way to avoid it.

Question - Should the vent arch be built on the insulation board or directly on the hearth? I am planning some sort of thermal break. Perhaps insulation under the vent floor but vent arch on the hearth?

[bpal]

I got the dome closed this past weekend!

Now on to the vent arch. I am waiting for the ceramic fiber braid that I ordered before I mortar anything in.