36" in Provo, UT, USA

[paulkjrobbins]

I have benefited so much from advice as I've gotten started I figured its time I post some photos. I started out planning and building a 42" pompei but later decided to do a 36". This was after I had already puored the foundation, walls, hearth slab, vermicrete, and cutout FB. As a result, my oven is on a large slab with room to spare for a little counterspace. I am doing 4 1/2" firebrick floor on 2" FB & 7" 5/1 vermicrete. Here are some pics of where I am right now. I used my straight edge to check for level. The center ended up being right at the edge of a brick so I decided to do an "L" insert for my IT. It is set high right now so it can reach the first course and then I will inset it so that it represents an accurate fulcrum.

[paulkjrobbins]

Here are some close-ups of my IT. It is not pretty but it works. Tried to make it without a trip to the store, ended up having to get a threaded rod. As you can see, I have a welder, it doesn't mean I am a welder.

[JRPizza]

... I have a welder, it doesn't mean I am a welder.

That's funny and describes my level of welding talent too You might want to make a thinner/reduced brick holder for those courses up near the top when the bricks get smaller.

[UtahBeehiver]

Plus one on JR's comment on the width of the "L" bracket. I even did on about an inch wide for the top courses.

[paulkjrobbins]

I ended up cutting the tabs off so that I could use it to figure out my inner arch length. It is 2" wide now. I can always cut it down again with my angle grinder if needed. Thanks for the tip. I am going to try 5" for my inner arch depth. It looks like that will work. Not sure if there is a benefit to it being shorter or longer but others seem to be around that size.

[UtahBeehiver]

You really cannot set a specific length depth, the TDC is the longest brick and defined by the IT. Each brick either side of the TDC changes as you move down the arch so you CANNOT cut all the arch brick the same. They are not linear cuts but skewed. Look the the pic I sent a couple post ago of a hemi or axed arch from Mr. Chipster build and you can see that each brick changes. That is why a full 9" brick to start out with is important. Build your arch form, then place the TDC and mark the angles with your IT. Then looking from the inside out and right side of the TDC brick (after it is cut) becomes the pattern for the left side of the next brick right of the TDC, then use the IT to mark the right side of the same brick. Repeat the process to the end of the right side of the arch then you do the same thing on the left side of the TDC. Again, the arch bricks change as you move down the arch. This is a very tough concept to mentally visualize but once you see it in person the light bulb goes off.

[paulkjrobbins]

Hi everyone,
Feels like it has been a while since I've updated. Not much of an update. Work, Rain, and the flu have been getting in the way. Still haven't mortared anything. I have started to cut out arch bricks. my inner arch form is 5" which I've found is giving me plenty of room on the backside for all the bricks, including the TDC which is the biggest cut. I think I am going to build the arch one step up at a time while I build the dome as I see others have done. Has anyone noticed a benefit to building the arch first?
I also had the idea of scoring the firebrick a little with my angle grinder on surfaces that are going to be mortared to give it better adhesion. I've done some tests with homebrew on scraps and seems to have ok adhesion. 24 hours after mortaring, I can pull it apart with some muscle, the thing that bothers me is that it pulls apart very clean on the brick surface. Maybe I am just used to metal and wood where the joint is stronger than the homogenous part when done correctly. Pre-scoring seems like a pretty quick thing to do to give it some better bonding. Has anyone heard of anyone doing this or see any negatives to it? Thanks in advance for any advice you have.

[UtahBeehiver]

You just need to mark on you arch template where the mortar joints are at each arch brick so you do not get mortar creep and get out of alignment and the the TDC brick not fitting.

[paulkjrobbins]

Thanks Russell,
I cut a few bricks thinner than 2 1/4" to get them to fit snuggly across the top of the arch. Since they are not tapered I am planning on them meeting without visible joints as seen from the bottom of the arch then having a wedge-shaped joint as they go to the outside of the arch, similar to the dome bricks (not tapered). If my plan is right, then I'll just be marking the brick joints on the arch form and follow those as I work my way up.
I heard northern Utah may get snow this week and we had some crazy rainstorms this week. I had a canopy over the oven but it blew away and everything got caught in the rain. My FB got wet but appears to be firm, hoping it will dry off and be ok.
I tried pre-scoring brick faces with my angle grinder before mortaring. I can't pull the bricks apart after a day of setting. Unless there is some other factor that I am not accounting for the scoring seems to add some strength to the joint. I was able to mortar my first two courses which brought me to the top of the cooking hearth and the majority of the third course. So far so good, I think. I'll upload some pictures soon. Thanks for all your help and advice.

Best,
Paul

[paulkjrobbins]

Hi Everyone,
I haven't been on in a while. I've trying to steal minutes here and there to lay my dome courses. When I got nearer the top I found that I needed to cut some lengths of wood to support the bricks for a while after I removed the IT. It got hard after the 45-degree mark. For the last courses I ended up making something to form the bricks on, partially inspired by how Russell did his with a carjack. I used piece of foam board from the dollar tree to cut out some ribs that matched my radius and a piece of pvc I had lying around and a hot glue gun to stick everything together on a some plywood. I still have a little more to go. My hole is about 6" wide so I'm hoping I'll get a little time tonight to finish the job.

[paulkjrobbins]

I have been looking at photos of other's outer arch and some of them look like the brick is pretty thin. I was wondering if anyone would be willing to tell me how thick their outer arch was? Was there a reason for making it thinner outside of not using as many bricks? Did you want it to meet the inner dome on the outside so that the FB wrapped across them nicely?
I am thinking of doing either a 1 1/2" or 2" reveal between the inner or outer arch. If I were to make it thinner to match the outside of the inner arch, this would make the bricks 3" or 2 1/2" thick. Of course, If I continue down this rabbit hole and make it 2 1/4" thick then that would save some bricks (almost out and need to get more) as I could just place them on end. Does anyone see any problem with this?

Thank you for your help! Tonight I'll see if I can't close the dome and then start on an outer arch template.


Best Regards,
Paul

[paulkjrobbins]

I have been thinking about rendering my dome and not enclosing it as originally planned. I know I will need to drill a hole through the hearth for drainage and I will be flashing and sealing around the bottom of the oven before the final render. I am not sure what the final finish will be so I am really just wanting to protect it for the winter here. I am thinking of coating it in either thoroseal or flexseal. Flexseal is significantly cheaper and easier to use but I don't see anyone using it on the forum. Does anyone have any experience with this? Thank you for your help.

[CoastalPizza]

I used Seal-Krete concrete sealer to waterproof my rendered dome. I used Quikwall for the first layer of render — it is a stucco mix with fiberglass fibers so it resists cracking a bit better than regular stucco. I've had to reapply the Seal-Krete each year. Also, I had to fill some small cracks that appeared after about two and a half years; I did this when the oven was warm so that the cracks were as open as possible.

The advantage of the Seal-Krete is that it is clear so the color I added to the render is maintained.

[paulkjrobbins]

Just took the syran wrap off the dome today (4.5" firebrick + 1" homebrew). I've had a 500W halogen inside with a thick greenhouse film over it for the last 4 days. The steam poured off of it! It was a sauna inside. No cracks after 4 days. I am going to put the fiber blanket on tonight. Been going back and forth on what the final layer is going to look like. Been waffling between an enclosure and a pebble finish with a roof over it. I am thinking I might do an enclosure out of river rock which is plentiful nearby then put metal roofing over it.

[paulkjrobbins]

Hello everyone,
It has been a little while since I posted. My oven is cured and mostly dried out. Got it up to 950 degrees F last night. I can't see any cracks but from what I've read they are probably there or will be with time. I am currently building a hexagonal roof out of metal studs with 1/4" hardie board for sheathing. The walls are made of ferrocement and make a column around the oven that breaks at the gallery. I wanted to shingle the roof but am wondering about nailing through 1/4" hardie board. It seems like it might break. Does anyone have any experience with this? The alternative would be Thank you for your help.

Best,
Paul