42" build in McPherson KS

[slschoming]

I finished the inner arch and ordered a tube of inswool pumpable caulk last night.

How soon can I remove the shims and pop out the arch template?

[slschoming]

I saw on another page that I could probably remove my arch template now, so I will try it today. Hoping I don't have too much sloppy looking mortar mess under there..

UtahBeehiver it looks like your bricks are cut at an angle and are just barely touching on the inside of your outer arch? Is that homebrew circled in red? Then you stuffed in the ceramic rope and sealed with the high heat caulk?

[UtahBeehiver]

That is correct, this was to minimize thermal transfer between inner arch and vent area. But I do like how Gulf did a "L" shape brick for vent area for his thermal brake as well. Look at his build.

You should be able to drop arch as soon as mortar sets up. Save you template since you can use it for laying your door. The release is a little small,so you have to be really careful because the form will be tight and you risk disturbing the arch joints.

For all you builders out there, make sure you have at least a 1/2" so the template will come out easier.

[slschoming]

The release is a little small,so you have to be really careful because the form will be tight and you risk disturbing the arch joints.

For all you builders out there, make sure you have at least a 1/2" so the template will come out easier.

Yes, I worried about it being too tight, but not until I had already set some of the bricks and was stuck with my mistake..

Fortunately, my template is some 2x4 framing that is smaller than the arch sandwiched between two pieces of plywood and all screws are accessible. If I have to, I can unscrew it all and get the front piece of plywood out with a little patience and preserve that for a door template. Then the rest of the wood can be sacrificed if it's too tight... I might also be able to pull the floor bricks out from the front as well once I remove the shims..

I will check out Gulf's thermal break. Thanks for the tips as always!

[slschoming]

I lucked out and my arch template came out very easily but I will have some cleanup to do, followed by a little pointing.. Any advice on removing excess mortar that has already hardened? Grinder?

[JRPizza]

Gulf's build was one of the ones I copied when I did the L shaped brick trick for my vent arch. It not only provides a nice way to get a door reveal around your inner arch but also provides a horizontal surface to put a length of insulating rope to seal off your heat break.

[slschoming]

I like the idea of the L shaped vent arch. I assume if I go that route I'll need to fill in this gap (circled in red) with a little wedge so my inner arch is a consistent distance from the vent arch all the way around?

Also, can the vent arch and chimney be built with regular brick? I plan to finish the outside of my dome similar to cobblerdave's oven and I have been accumulating old house bricks for this purpose. It might be nice to do the vent arch with house brick from the start so there is no extra layer required around it when I'm done. Does that make sense?

[UtahBeehiver]

I would not recommend regular bricks on the vent area or interior of the chimney, too hot. A chimney vent on a fireplace will have a clay liner. Speaking of chimney vents, the existing shape of the arch does not lend itself to a heavy chimney load without buttressing the side walls. So if you build a brick chimney of any height you will need to buttress the side walls.

[slschoming]

UtahBeehiver Thanks, that's exactly what I needed to hear.. I will plan on building with firebricks.

I have read many comments on here that refer to buttressing and I have looked it up but I'm not sure I fully understand.. If I build straight vent walls and match the arch of my inner arch (adding enough width/height to allow for a reveal) all with firebrick and build walls outside of the firebrick walls using regular house bricks would that be sufficient buttressing? This is my first masonry project and I am trying to learn as much as I can as I go.

I am also not opposed to putting a duravent on top of a simple arch with minimal weight on top if necessary, just thought I could save a little cash by doing a brick chimney.

I like the look of a shorter brick chimney, but I also want it to work properly. What is the minimum recommended chimney height?

[UtahBeehiver]

With a full hemispherical arch, think a half moon shape, the downward load of the arch is pretty vertical. With a half arch like yours the load moves horizontally, think of Notre Dame church walls with domes sitting on vertical walls. They have buttress supports to offset the horizontal load of the dome at the vertical wall joint. You can probably get away with is small brick chimney like Cobblestone Dave (notice on Dave's build his does buttress his outer arch. but not a full height, full chimney like Gulf's.

[UtahBeehiver]

Load Diagram

[cobblerdave]

Gday
Its a while since I built my oven wow that long. Having a oblong dome opening sorta lends itself to a wide chimney. It’s also short, the domes the same height. It doesn’t have to draw as the smoke goes straight up from the entrance and out. The winds here come from the direction faced by the oven entrance but we do get the occasional strong westerly in august. The wind from behind the oven will get forced down the chimney and blows the smoke in your face. Pretty rare though.
The rear of the chimney is firebrick but the rest is brick commons, thats solid clay not house brick the ones with the holes.
Id buttress so it’s double brick ....lots stronger
enjoy the journey
Dave

[slschoming]

I made more progress on the dome yesterday. I started using thirds instead of halves on course 9. There is some ugly stuff that I am not proud of going on where the dome meets the top of the arch, but it is solid and no one will ever see it.

I have 3 courses left + keystone so I need to get serious about what I'm doing for the chimney.

cobblerdave Here's a rough sketch of how I am picturing my finished product (subject to change). I will do a double wall below my arch like yours, but then get more narrow on the way up the chimney. I think I'll use clay flue liners so I can use old brick commons instead of firebrick. The chimney will probably extend about 2 feet above the dome.



UtahBeehiver My neighbor stopped by while I was working and said "It looks like you're almost done with your beehive" and I thought of you.

[UtahBeehiver]

The sketch shows adequate buttressing. For the dome, it looks like you want to brick the outside. I suggest you look at how Gulf did his, He sliced his brick side make about 1" veneers. Looks really nice.

[slschoming]

The sketch shows adequate buttressing. For the dome, it looks like you want to brick the outside. I suggest you look at how Gulf did his, He sliced his brick side make about 1" veneers. Looks really nice.

Yeah, I am planning to slice the old bricks that I have been collecting down to 1-2 inches thick (varying slightly for an intentional uneven look). I am going for a "been here for 100 years" look and will be using a mix of reds, yellows, and darker bricks (similar to cobblerdave ) if I can find enough of each color.

Gulf what material / how thick of a layer did you put between insulation and exterior brick veneer?