Dreamer turning to "do-er"

[Blairt]

I still feel lost on where the arch should be. After JRPizza reviewed my cardboard mock-up I thought I had the arch pretty much properly placed but deejayoh says it should be further forward. The arch is lined up with the inner mark which is the outer edge of my floor bricks. I’m stalled until I can lock in the arch placement...

I understand that the lowest arch brick needs to have angle cuts to then line up to the lowest level of the wall bricks (I’ll be placing this lowest course as a header brick, lying flat on the insulation - with a slight amount of firebrick/sand compound for leveling as required.

[UtahBeehiver]

IMHO, the placement looks good with the inner edge of the arch form intersecting the inner diameter of the oven as shown in post #23. The top dead center will be the longest final cut brick and the the shortest final cut at the bottom. Refer the post I had shown earlier on how the IT sets the angles.

[Blairt]

Thanks Russell!

I'm leaning towards NOT tapering the arch bricks but rather leaving them full 4.5x2.5" width and using additional mortar to fill in the wider gaps that would result. This seems like a lot less work and cutting the full 4.5" width of the bricks would be a challenge with my saw. Would this change your recommendation?

Also, in order to get a bit more height for larger pans etc I'm leaning towards using half bricks on edge rather than on the flat for my bottom dome course. (Half soldiers)

[UtahBeehiver]

Tapered inner arch are more work up front but saves a lot of time on the back end and makes the transition to the dome much easier and cleaner. So like the Fram oil commercial, pay me now or later. Half height soldiers or half headers will work either way. In reality you really do not gain much vertical space with half soldiers but that is up to you.

[JRPizza]

Tapered inner arch are more work up front but saves a lot of time on the back end and makes the transition to the dome much easier and cleaner. So like the Fram oil commercial, pay me now or later. Half height soldiers or half headers will work either way. In reality you really do not gain much vertical space with half soldiers but that is up to you.

Russell, I think Blairt was talking about leaving his bricks rectangular when looking at the arch from the front and having triangular wedges of mortar vs tapering the sides of the bricks and having a constant thickness of mortar. I think you are talking about tapering the rear of the bricks where they intersect the dome, which indeed makes incorporation into the dome easier and cleaner. Just wanted to make sure we weren't getting him too confused.

Also Blairt if you are not sure the arch is placed right do as I suggested. Put your arch form where you think it should be, and draw a line across the front edge of your form on your cardboard. Extend the line out using a ruler. Measure from the center of the arch along that line a distance equal to the height of your door. A brick laid at the end of that line with the forward lower edge touching the line is where a tdc brick will sit on your completed arch. Make sure that brick is in the double circles like I showed in the sketches I attached. Any other method is really just "eye balling" and not guaranteed to get the arch in the right place.
I struggled like you did and created a thread where Gulf helped me understand where my arch should go and how to use a large scale template.
https://community.fornobravo.com/for...18-hearth-size

[MarkJerling]

I still feel lost on where the arch should be. After JRPizza reviewed my cardboard mock-up I thought I had the arch pretty much properly placed but deejayoh says it should be further forward. The arch is lined up with the inner mark which is the outer edge of my floor bricks. I’m stalled until I can lock in the arch placement...

I understand that the lowest arch brick needs to have angle cuts to then line up to the lowest level of the wall bricks (I’ll be placing this lowest course as a header brick, lying flat on the insulation - with a slight amount of firebrick/sand compound for leveling as required.

The placement of the base of the arch is determined by where the brick at the top of the arch intersects the dome. So, you need to find that position. That can be done in various ways: You can use an IT or you can use a cardboard template, for instance. The trick is that the brick at the top of the door arch must intersect the dome because your dome courses needs to coincide with that top of door arch brick location. Put another way, that's the innermost location necessary for your door arch bricks.

Once you know where that brick needs to be, you'll know where your arch needs to sit and consequently where you need to set the base of your door arch.

[UtahBeehiver]

JR, makes more sense after I re-read the post. The joints are fairly wide on the exterior end but I have seen many ovens built this way. Only would caution those who use a commercial mortar such as HeatStop to be a little careful on joint size since the recommended joint width not exceed 1/2" although I have seem some builds with HeatStop or equiv. with much larger than 1/2" joints.

[Blairt]

Been a busy week. I have my dome finished! It sure won't win any awards for beauty but should be functional. I'm amazed at the amount of fireclay left after cutting! I've given the dome a coating of homebrew and will do another over the FB blanket next week.
The "bump" at the top is a result of a full brick that I covered in mortar when I covered the keystone in the dome. Just thought the extra depth and insulation wouldn't hurt rather than cutting the brick to just fit over the keystone. Since I'm building a doghouse enclosure, the aesthetics of the exterior aren't high on my agenda.

Moving on to planning the chimney...

[MarkJerling]

Wow! You have been busy. Well done!

[Blairt]

Thanks Mark. It has been challenging for someone with zero masonry skills and few mechanical skills!

[MarkJerling]

Well Blair, when I started mine, I'd never laid a brick in my life! LOL

[Blairt]

Hi all. I have a couple of questions:
I’m planning an expansion gap between my inner arch and the entryway. I have 1/2” ceramic rope to fill the gap but wanted a high temp silicone as well. Having a hard time finding this locally. Even our two local fireplace stores don’t carry it. What temp rating should I be looking for on this silicone?
i am building a doghouse style cover over the dome. Once I lay the FB blanket down I plan on a coating of mortar and then vermiculite over the entire dome. I have four bags of vermiculite, each 4 cubic feet. Would it be ok to just pour this loose over the dome or should I make a mix of v-Crete ?

[deejayoh]

Hi all. I have a couple of questions:
I’m planning an expansion gap between my inner arch and the entryway. I have 1/2” ceramic rope to fill the gap but wanted a high temp silicone as well. Having a hard time finding this locally. Even our two local fireplace stores don’t carry it. What temp rating should I be looking for on this silicone?
i am building a doghouse style cover over the dome. Once I lay the FB blanket down I plan on a coating of mortar and then vermiculite over the entire dome. I have four bags of vermiculite, each 4 cubic feet. Would it be ok to just pour this loose over the dome or should I make a mix of v-Crete ?

I used Kaowool high-temp caulk, and it worked great. You can find it at pottery suppliers - https://www.sheffield-pottery.com/Hi...wool-p/tcm.htm

As for the vermiculite, you can pour it in loose. no need to form it, just fill up your doghouse. Personally, I think that's overkill if you've put on a few inches of blanket, but then again - you can't really go back and add it later.

[Blairt]

Thanks Deejayoh! We have a pottery supplier in the next town over. I'll check with them or purchase online.
on the vermiculite, I've heard that it's hard to have TOO much insulation so I want to push that envelope. As you say, I can't really add it later.

[david s]

Basically you want a material that is both flexible and not conductive. Forget high temperature silicon in that position, it is too hot for it. The idea is to use material that is a bit flexible and one that is fireproof and is not conductive. Any fireproof calks that I’ve tried set hard when heated and are no longer flexible. Correct me if anyone has found a product that doesn’t go hard. The ceramic rope remains flexible and a lean vermicrete brew remains a bit flexible.