How to build the chimney transition???????

[Santino]

So I've spent about 4 hours today attempting to build my chimney transition and all I got done was to cut 6 bricks. The rest of the time has been spent staring at my oven trying to figure out what the hell to do. I seriously might go crazy soon.

I don't know if I built my arches wrong or what, but I never really saw any threads about vent opening size. One problem I can already see is that my anchor plate for my stainless steel pipe is 1" larger than my opening. My vent opening is about 6" x 12" and my Duravent pipe is 7"ID (9"OD). I can not figure out what to do. I have tried several different dry runs and I'm completely lost. Do I need to use a grinder and cut away part of my middle arch? I was hoping I could just build a raised platform and let my anchor plate sit on top, but again, I can't figure out how to do it. I am a foodie - not a builder!

Can someone please, please, please help me? I have posted some pictures of where I'm at and what I was thinking about doing.

1st pic is where I started this afternoon.

2nd pic is the cuts I made to work towards a level base for the anchor plate.

3rd pic shows what I was thinking about doing with creating a platform of sorts. I was going to create a square-shaped platform with wedges underneath. In this picture I only took it with bricks on the left and right.

4th pic is a just a birds eye view of the anchor plate sitting on the vent. You will see the overhang because of the 6" space and the 7"ID on the anchor plate.

Hopefully some of you guys will have recommendations that will be an easy fix...............

[Neil2]

Re: How to build the chimney transition???????

"The rest of the time has been spent staring at my oven trying to figure out what the hell to do."

This is what we all spent a lot of time doing when building our first oven.

It looks like you are on the right track though.

[Santino]

Re: How to build the chimney transition???????

Oh, I don't doubt that one bit. So I guess that means you're not gonna give me any advice?

When I say I'm stuck, I'm really stuck right now. Maybe it's because it's 93 degrees out today and I all I did was bake in the sun, but I'd really rather be baking pizzas than myself!

[mrchipster]

Re: How to build the chimney transition???????

I would build a support back over the inner arch and elevate it one brick to aid in the transition to the flue plate.

Chip

[Tscarborough]

Re: How to build the chimney transition???????

The first thing I would do is buttress the arch. Then I would cut brick to bring it level to about the height of the top of the dome and then set the plate.

[Santino]

Re: How to build the chimney transition???????

Thanks guys I appreciate the advice.

Chip, I do plan on putting some extra support towards the inner arch and dome as well as towards the front. I think I may have figured that out this afternoon and will post some pics to see if you guys think I did it right.

Tscarborough, I know what you mean by buttressing, but don't understand if there is right and wrong way to do it. Do those bricks that I cut to tie into the middle arch (2nd pic) need to somehow be specially cut to tie into the bricks that are buttressed, or can I just mortar those cut bricks to the buttressed bricks? The buttressing concept has been the hardest for me to grasp because most people have taken a lot of pictures only of the finished product, but not how it ties into each step of the process. I've gone as far as researching the topic in architecture, but it's a little different looking at used in some museum or church compared to a pizza oven!

[Santino]

Re: How to build the chimney transition???????

Hey guys, does this look good? By good I mean structurally and functionally. If it looks like crap, but still works, then so be it!

The good news is it seems to draw smoke very well in my first test fire today. If someone could explain the buttressing thing to me, it would be much appreciated.

[Lburou]

Buttressing?

I think what Tscarborough is saying is to put some support around your entry arch, like a picture frame. Just high enough to support the sides of the flu.

I located the front of my enclosure in the middle of my entry arch (see below). Using insulated fire bricks to buttress the arch, I used clay flu liners and put brick around that for the chimney.

Have you looked through the photo gallery for examples showing entry arches?

HTH

[mrchipster]

Re: How to build the chimney transition???????

I have a corner entry and plan to fill the area around the entry with perlite concrete. It is not strong in tear / shear strength but very good in compression so there would need to be a solid support backing up the mix. In my case I am doing a brick enclosure backed up with concrete blocks so nothing is going to move. The perlite mix acts as a gap filler between the vent arch and the outer brick wall and provides a great buttress.

One other item regarding the buttress of an arch, the buttress/support only needs to go up the sides of the arch a maximum distance of 2/3's of the way to the top of the arch. After that it is just producing additional top loading of the arch potentially putting more stress on the buttress.

Chip.

[GianniFocaccia]

Re: How to build the chimney transition???????

One other item regarding the buttress of an arch, the buttress/support only needs to go up the sides of the arch a maximum distance of 2/3's of the way to the top of the arch

Hey Chip,

Is there a site or documentation that you can recommend I read to bone up on this? I've read through the vaulted structures pages on the Auroville Institute site, but haven't seen a site covering buttress dimensions.
Thx,
John

[mrchipster]

Re: How to build the chimney transition???????

Hey Chip,

Is there a site or documentation that you can recommend I read to bone up on this? I've read through the vaulted structures pages on the Auroville Institute site, but haven't seen a site covering buttress dimensions.
Thx,
John

Just something I remember from my engineering classes. I will try and find some supporting documentation and pass it along.

Chip

[Santino]

Re: How to build the chimney transition???????

Hey guys, thanks for your replies. I am doing an igloo enclosure so I won't have the luxury of completely encasing my arch. So if I go up 2/3 of the way with my buttressing, would I start it from the concrete hearth?

Also I'm trying to determine how to build my chimney. I started another thread, but no one has responded yet, so maybe you guys can help. Would it be too much weight to build around the stainless steel pipe (and all the way up) with firebrick? Or is there a way I could build around it with regular brick (since it is lighter - and what I really wanted to do)? You can reference page 58 of the Pompeii plans for what I'm talking about.

The other option would be to stucco the chimney pipe, which I saw done in the Pompeii plans. I would do this if I could just understand how to do it. Any ideas?

[mrchipster]

Re: How to build the chimney transition???????

I guess that would depend on what you are going to do with your decorative arch . Is it going to be larger than your flue arch?

The igloo style does not leave you much room for buttressing so you might want to create a steel buttress out of a piece of angle iron to support the arch.

That way you could have a very thin profile, and still provide support to the sides of the flu arch. the angle iron would be mounted directly to the base and contact the sides of the flue arch but not be directly attached to the arch with any fasteners or mortar. It would just snug up against the sides of the arch to provide support.

There are several examples of this in the photos available on the FB site.

With regard to the stainless steel flue and the brick, if you leave a gap between the stainless steel and the brick, firebrick will not be required, Except where the flue is mounted to the arch.

I assume you're using a single wall stainless steel flue, And you will want to use some sort of transition plate to support the flue.

Chip

[Santino]

Re: How to build the chimney transition???????

Chip, thanks for your reply. I had planned on leaving my arches exactly as you see them now. I was hoping to leave the front of the outer arch exposed, and then have everything else covered with regular brick to hide the fire brick.

My stainless steel pipe is a 7" double-walled Duravent pipe. I didn't want to have the base of the pipe near the flue showing firebrick and then have regular brick going up to the top of the chimney pipe. So I was hoping I could somehow "wrap" the outside of the arches and all the way up to the top of the pipe in regular brick. I hope this makes sense. Essentially, just like the oven on page 58 of the Pompeii plans.

Otherwise I would want to stucco the whole thing (including the pipe) like the oven next to the brick chimney on page 58 and put a chimney cap on. I just don't know how to stucco the pipe. Can I stucco directly over the pipe? Does it need to be insulated and have chicken wire over it before I stucco? If this would be easier to accomplish, I might just do this.

If you (or anyone else) have any suggestions on how I can accomplish this, it would be greatly appreciated. I literally have no idea and would hate to get this far to screw my oven up.

Essentially I want my chimney to look like one of the two igloo ovens on page 58 of the Pompeii plans. Whichever one is easiest to do is preferable to me. I just want to start cooking!

[Santino]

Re: How to build the chimney transition???????

One other question (and maybe an easier solution)...

How long will a Duravent SS pipe last exposed to the elements? My worry is that it will rot or rust after several years and I will have to replace it. Plus I just don't really like the look of it exposed. I just don't want to have to do any repair work to the structure of this oven for a long time, if ever. I would rather patch up some stucco or something similar than to have to take things apart.