I'm back

[Amusinglisa]

3)There are a few bricks on that inner arch that are definitely not presenting a flat face. Poor planning/flying by seat of pants. The current idea is to get in there and grind away all the not-flat-ness before making a door template.

2) The plan is for the vent/chimney opening to be a bit below this arch -- it is the decorative part per the sculptor's request. I have to take a look at how I am going to make that chimney fit. it is a 10" diameter. The dome is 34" diameter but 22" tall. I know it is a bit of overkill, but if it will work and I can keep it out of the landfill... I have sincere doubts and will be heading to the Fireplace Store tomorrow. Is there a compelling reason to go with a double (or triple!) wall chimney vs. a single wall if I am going to have an inch or more of 5:1 vermiculite:concrete insulation around it? I could add ceramic blanket as well.

1) I can definitely butress the outside of the arch. I will probably put two soldiers there or two bricks stacked. (Just noticed that they are not of equal size. =D I'll have to fix that.

[SableSprings]

If you've got a 10" inside diameter chimney, you're golden! Even dented, a chimney that size will work very well for your oven. (Put the good looking side of the chimney to the front of the oven...)

On the buttressing, you want lateral strength and support for the arch. Laying bricks so they are perpendicular to the opening is the way to go (a stretcher and header combo is what you want, not a soldier formation). You'll want to use the stretcher/header combo up until you get halfway up that outer arch. That way the length of the brick is providing the buttressing and alternating the stretcher/header pattern makes it REALLY STRONG. Here's a link that shows the various ways a brick can be laid--just to make sure we're on the same page with the terminology ( https://en.wikipedia.org/wiki/Brickwork )

Most folks use a single wall stove pipe on their ovens unless they are going through a roof. Forno Bravo sends you single wall, stainless steel 6" diameter pipe with their Casa2 G90 kits (and others) planned for an outside installation. Double walled chimneys are made for the insulation of hot pipe from combustables (i.e. when you put your chimney through a roof, the section that passes through must be double wall insulated pipe usually mounted in a hanging bracket that adds an air gap as well). For your oven, the purpose of the chimney pipe is to release the smoke higher--above the pizza crowd. We used the same refractory mortar to both assemble a Casa2 G90 modular kit and secure the single wall pipe to the top plate above the smoke chamber. I'm not sure if using the perlcrete would be a good idea since it really doesn't provide the kind of strength you need to secure the pipe.

I also think that you will want to look for a cinder screen cap to go on top of the pipe. It's amazing how far a piece of ash/hot cinder can travel after it leaves the chimney...and none of us need another wildfire . Here's a link to a Home Depot square cap, just to confirm what I'm talking about...I know there is a round version as well.

https://tinyurl.com/ydb9ykst

[Amusinglisa]

Oh dear. I thought I had posted a response. Trying again:

THank you, again, Mike. Just having a sounding board is great!

Is this what you mean by stretchers and headers?

I'm going to need to rake the chimney a bit. THink it would be OK to cut and crimp that 10" monster?

Definitely planning on a spark arrester. We are in a rural community and cannot afford a wildfire. Ever. Too scary.

[SableSprings]

You're going to need to come out more with your arch vault. At least one full brick (9 1/2") length. The middle (single brick) in your stack is a stretcher. If you turned it 90 degrees, so the end was facing front...that would be a header. The link I put in post #47 takes you to the Wikipedia page, and going down that page you'll see illustrations that show this. I'm adding a couple of pics from my build that should help explain better than my poor verbiage.

So, in the pictures below you'll see that I choose to stand two sailors with a shiner on top (the three stacked firebricks coming out of the oven) on each side of the landing. That set up for my outside arch. Then using half and full sized common bricks, I laid a half brick in header orientation against the outside sailor and alongside it a parallel full brick also in header orientation. The second row of the buttress is a full brick stretcher in front and a half brick stretcher behind it. The pattern repeats up to where I tied in the arch. The buttress has enough lateral strength to offset the outward press of the arch. I even stuck a few pieces of rebar in the holes of the commons and threw in concrete to lock everything together.

I also added a couple of pictures that show the progression of the arch/vault build with one and my inverted flue pipe smoke collection area. (Although I built my outside arch too high and the smoke can roll out the front lip fairly easily until the flue gets fully heated and starts to draw strongly. My solution is to lower that front arch by a couple of inches with either a metal piece or inserting another arch (doable, but I think a metal piece across the top would be much easier ).

I don't see why it would be a problem to cut and crimp the 10" pipe. How long a piece is it? Might be a good idea to make some flanges at the base where you're cutting and crimping that come out at 90 degrees from the pipe. That way when you mortar it into place with the flanges embedded, it will be pretty darn solid. Try to be careful cutting and crimping, you don't want to create a situation where the smoke "wants" to follow a bad crimp/fold/cut instead of up the pipe and out (...and also it's pretty easy to get a nasty cut working with that metal, be sure you wear good gloves and eye protection). FYI: You are definitely going to want to secure and seal the base of the chimney pipe with mortar all around.

[Amusinglisa]

AHA!! That is exactly what I needed!!!

[david s]

As you don't have an anchor plate you could fit the pipe the way I do (see pic). Far cheaper, simpler and doesn't require drilling into brick, anchors or screws, all of which are subject to corrosion and loosening or creating cracks when they expand. I've found through bitter experience that the pipe needs to be a slightly loose fit as it can crack surrounding brick or refractory when it expands first. Going up higher with your bricks will also get this pipe fitment further from the flames so it's a bit cooler. I use a 5:1 vermicrete packed around the base of the pipe. This allows a little expansion and makes removal of the pipe (hopefully never necessary) easier.

[Amusinglisa]

david s - that's what I am hoping to do! What did you use ti fit that? Is it the vermiculite concrete mix and a form around the chimney? That would help me with raking it a bit...

So, based on the final exterior, the plan is to curve the front of the outer arch forward, using braces and going one brick at a time. It is an interesting idea, but not sure how it will work. I am guessing it will hold up once we cover it all with insulating concrete...

Any thoughts on that crazy idea?

[JRPizza]

Do you have an sketches of your final design you are willing to share? It is kinda hard for me to visualize where you are going with the extended curved outer arch, and a clearer idea might help folks make suggestions.

[david s]

david s - that's what I am hoping to do! What did you use ti fit that? Is it the vermiculite concrete mix and a form around the chimney? That would help me with raking it a bit...

So, based on the final exterior, the plan is to curve the front of the outer arch forward, using braces and going one brick at a time. It is an interesting idea, but not sure how it will work. I am guessing it will hold up once we cover it all with insulating concrete...

Any thoughts on that crazy idea?

Yes, I use 5:1 vermicrete between the mesh and the pipe. 10:1 vermicrete outside the mesh and the render/stucco over that. This results in good support of the flue pipe base and allows moisture to pass from the vermicrete, through the The mesh and to the atmosphere. The stucco should not be in direct contact with the pipe or it will crack.

[Amusinglisa]

david s. I am having some trouble thinking this through. Looks like you have a chimney mounted on top of a masonry "pipe" which I am guessing is your molded/cast vent? Is that then installed as if it were one large brick? Would making a flared piece to sort of drop into the opening work? If so, I could incorporate all the odd angles I would have both from the monster pipe being a bit squashed and to rake it back...

No no worries on cosmetics as it will be completely covered with vermicucrete.

JRPizza - here's a sketch - my medium is not paper/pencil (I do art glass, though) so it's a bit odd. Drawing it is definitely helping me see it better. Thank you!

[JRPizza]

Ah, I can see some of what you are trying to do with the vent. As an option you could always use a standard flat adapter and put a 45 on top like the one below, and top off with a straight section.

[david s]

david s. I am having some trouble thinking this through. Looks like you have a chimney mounted on top of a masonry "pipe" which I am guessing is your molded/cast vent? Is that then installed as if it were one large brick? Would making a flared piece to sort of drop into the opening work? If so, I could incorporate all the odd angles I would have both from the monster pipe being a bit squashed and to rake it back...

No no worries on cosmetics as it will be completely covered with vermicucrete.

JRPizza - here's a sketch - my medium is not paper/pencil (I do art glass, though) so it's a bit odd. Drawing it is definitely helping me see it better. Thank you!

Yes, that's correct. Casting a flue gallery is much easier than trying to create a complex form in brick.

[Amusinglisa]

Ah, I can see some of what you are trying to do with the vent. As an option you could always use a standard flat adapter and put a 45 on top like the one below, and top off with a straight section.

Yes. The ONLY reason to try to monkey with the monster double wall pipe I have is because I have it and using it will keep it out of the landfill.

In the end, the dome shouls support the majority of the weight of the pipe, with the remainder being supported bu the backand sides of the vent opening, leaving very little support for the front of the vent, so I am hoping the sort of cantilevered, wedge-bricked arch might work. I think it may be a little too much wishful thinking, however.

[Amusinglisa]

OK. I am having a horrible time with the outside arch. Making small batches of mortarso I can try cockamaimie ideas and let them set before taking them down.

the good news is that I am taking them down and so far, they are not falling...

Three questions:

1. does the outside arch have to be fire brick? Can it be redbrick? My guess is that I would rather have it pretty dang heat tolerant - just incase. THIS is not part of the project I want to revisit.

2. can I cast the front arch in vermicrete? I am hoping that because I will rake the pipe and its weight will be supported mostly by the dome, it might work...?

3.Can I cast thewhole front arch in vermicrete?

4. Is it beer o'clock yet???

[david s]

OK. I am having a horrible time with the outside arch. Making small batches of mortarso I can try cockamaimie ideas and let them set before taking them down.

the good news is that I am taking them down and so far, they are not falling...

Three questions:

1. does the outside arch have to be fire brick? Can it be redbrick? My guess is that I would rather have it pretty dang heat tolerant - just incase. THIS is not part of the project I want to revisit.

2. can I cast the front arch in vermicrete? I am hoping that because I will rake the pipe and its weight will be supported mostly by the dome, it might work...?

3.Can I cast thewhole front arch in vermicrete?

4. Is it beer o'clock yet???

1. Red brick is ok
2/3. You could use vermicrete, but a high proportion of vermiculite is very weak. I cast the front decorative arch in my builds in concrete, but replace half the aggregate in the mix with vermiculite and use plenty of random fibres for reinforcement. Actually I do it in two layers with the side facing the heat having a higher than 50% proportion and the outer layer lower than 50% that way the inner layer is more insulative and the outer layer stronger.
4. Always