42" In South GA

[edonovan]

Pictures are awesome mongota , thank you! I remember seeing your flared vent early on when I was reading through, but couldn't remember where...I will definitely be working towards a version of that and I feel good about my 12" entry and having room now. And JRPizza thank you for your rundown...make sense that you needed the extra room for the bolt down application. Will probably be getting out all my shims and begin my dry layouts today and markup my form so I know where mortar lines should be.
After my research, anyone have insight or verification that Duratech over Duraplus is the way to go...from what I have read people see that plus is tripled walled, but is actually not as good as the tech (doubled wall) product.

[mongota]

Being an outdoor oven and with a fairy short run of flue, the need for triple wall seems like a bit of an extravagance. My opinion.

My chimney is exposed, so visually the look was a factor (preferred stainless). I went with insulated two-wall. It's not too hot during a full fire. I bought from a place called NorthlineExpress. Price was good back then, delivery quick and undamaged. They had another line called Shastavent that I remember looking at. Less expensive but still stainless. I don't recall the wall thickness of Shasta compared to Dura or if they were different grades of stainless. But in the end I went with Duravent (2-wall, insulated, stainless). I bought two 48" pieces of pipe, I'm only using one now, When I rebuild my pool pergola I might need the other one for roof clearance. I checked my build cost: Chimney pipe (2@8"x48"), chimney cap, anchor plate & bolts: $362.00 for everything.
It appears prices have gone up! Ouch!

[edonovan]

mongota Yes, prices have gone up …did find better pricing at efireplacestore.com, already got my 8” anchor plate so I can make sure I have the room for installing it. I like the 10” square stepping down to the 8” flue, just nervous about only 1” front and back, I may toss around the idea of a 9” square. And as always I do have a couple questions.
1) really want to keep this as easy as possible and keep my momentum. Picture 1…any functional reason to cut a lip in the back brick of the entry to lay over my inner arch? (#1) I plan on putting high temp flat rope in (#2) and from what I can tell (#1) area is going to get covered with the insulating blanket.
2) picture (2) really didn’t realize what I was getting into on the flared entryway, but still like it and am making an attempt to simplify it…what I have going here…this is just going to be cosmetic, correct? If I only angle the back brick and allow the front to do/look like this, it is just going to not be a flat front arch and from what I can tell the angle gets less as I move up so it is just mainly for the flare (first 4-5 courses)…?

[mongota]

1) really want to keep this as easy as possible and keep my momentum. Any functional reason to cut a lip in the back brick of the entry to lay over my inner arch? I plan on putting high temp flat rope in (#2) and from what I can tell (#1) area is going to get covered with the insulating blanket.
2) picture (2) really didn’t realize what I was getting into on the flared entryway, but still like it and am making an attempt to simplify it…what I have going here…this is just going to be cosmetic, correct? If I only angle the back brick and allow the front to do/look like this, it is just going to not be a flat front arch and from what I can tell the angle gets less as I move up so it is just mainly for the flare (first 4-5 courses)…?

Morning Ed...

1) No. Not required. the L-cut overlap is completely optional. As silly as this sounds, when I bought my 1/2" CF rope, the length I bought just happened to be long enough for two gaskets at dome arch/landing arch junction. So I figured 'why not' and L-cut my landing arch bricks to overlap the dome bricks on two sides, and then used a double run of CF rope for a double gasket. Not required. Not necessary. These builds are very fluid. Abutting the landing arch bricks to the dome arch bricks with a gasket in the gap between between is perfectly fine.

2) My only real comment here is how are you detailing the finish surface of the landing arch opening? If you can successfully hide the angled brick ends at the front of your landing arch I don't see it as a factor at all. If those angled back brick ends will mess with any arch face geometry in terms of your finish detail? Meaning, will any part of those angling back arch bricks show as a reveal? If you have a reveal and the arch bricks angle back on the sides but not on the top, it might make for an uneven mortar gap which may or may not look sloppy and may or may not bother you. It might be easier to square everything up now. You know your finish details, so you can make that call.

If your landing is 1-1/2 bricks deep, in general, ~13-1/2" deep? When you cut your bricks in half, cut them with a slight angled cut to provide two identical half-bricks each with an angled cut on one end. Use one angled half-brick with a full brick on the left side of the arch, the other angled half-brick on the right side also with a full brick. You'll cut an angle on one end of each of your whole bricks as well, just as shown in your first photo. There's your first course.

With the sides of the landing arch being flared outwards a bit, and with the top of the arch being not flared, but flat/level? The length of the brick course will decrease slightly as you move towards top-dead-center of the landing arch, going from 'flared' to 'non-flared'. Not by much, just a fraction of an inch. No math calculations or measurements will be required though. Just keep the face of the landing arch bricks even with the face of your arch form. As long as the form itself is plumb/vertical, the face of your landing tunnel arch will be plumb/vertical. The top will be quite easy as the chimney vent hole will be there.

I hope all that makes sense!

EDIT to add a drawing. Hope that helps clarify my text. Left side of drawing shows full and half bricks with one end of each cut resulting in a clean face. Right side of drawing shows my concern, that an uneven gap may appear at the face of the landing arch, but that depends on your finishing detail.

[edonovan]

Thank you again mongota Ok, just what I was thinking on the cutting the back lip on the brick that it wasn't exactly necessary...I plan on just shoving what fiber rope/gasket in that I can and then some high temp silicone...As for the second part...you are asking good questions...I have an idea for my finished edge...Once I trim the excess insulation I have about 4" to the edge of my hearth...I have an image of just doing some classic red brick, built up to the same height of the entry floor and just going around the entry area sides and front (attached rough photo edit). As for the arch...I was planning on just leaving the fire brick....obviously the more I look at builds I tend to add ideas to my head and think "oh I could do that, or that, or that" then I come back to earth and just want to keep it simple...I feel like I could make the front angled brick look good with red brick by just doing a couple simple angle cuts on the red brick...and it is just that 1 layer at floor height that I would have to deal with. Your drawing definitely helped me think more about my end finish (which I sometimes I am not the best planner) I think I just don't want to have that cut edge as the front arch and would rather just have to cut the one back brick.

As I am try to do more of this planning stuff and figure out this entry area...from what I am reading...I need at least the 50 sq in of the 8" diameter Chimney as my flue gallery? Correct? Also, as I keep reading...I should be good with my 12" deep entry and don't need to have the typical brick and a half (13 1/2") entry. So If I just made my flue opening 8" by 8" that would suffice correct? That would leave me 2" front and back, and maybe at that point I should lip those top edge brick to make them a bit stronger to build my platform for anchor plate? Or would an oblong flue do the same?... maybe 6" deep x 9" wide...that would give me more to work with front and back. Lots for me to keep pondering...Please anyone give your thoughts/opinions, and I thank you in advance... and again thank you for your insight mongota it really is helping me step back before just jumping at it and not being entirely happy or in a situation that I would have to take apart.

[david s]

Yes, it is the cross sectional area that is important. A 6" x 9" will give you a shallower entry and make working the oven easier. 5 x 12 would be even better.

Using high temp silicone in that area won't work as the temperature will be too high for it to cope with. I could be wrong with your oven design so you could try it and if it fails replace it with something else.

[UtahBeehiver]

With an anchor plate, you will need to cut our the brick around the inlet of the anchor plate since the 8" pipe on the anchor protrudes below the face of the mounting plate. There are high temp sealants available but you will not find them at a big box store or the big A company. Morgan Thermal makes one called Kao Wool mouldable cauking in a tube.

[mongota]

Looks like the other guys answered your flue question.

As far as the front arch design morphing, it happens. My plan all along was to cover my dome with a ~4" thick stone veneer, but I was going to cast a decorative 2" thick 'thin shell' to cover my landing arch. Late in the build I decided to cover the landing arch with the ~4" stone veneer as well. That decision resulted in my having to cast a decorative front arch wider than I had originally intended so the arch would cover the firebrick plus the additional thickness of the stone veneer.

The visual of the front of the oven is bulkier than I had intended due to the wider arch. But the pizza tastes the same!

[edonovan]

You guys are awesome yet again... thank you for all the input... mongota definitely am understanding how plans continually change and just have to remember the pizza will taste the same ... UtahBeehiver that is what I had in mind for my anchor plate once I get to that point...been reading up on everyone anchoring it differently...to use screws or not...just sealant?...and/or bolts...I will keep reading and decide as I get to that point... david s ...thank you for validating my thoughts on the cross-sectional area...I think I like the idea of 6x9...my entry is still going to be 12" deep, but that gives me a little bit thicker brick on the back side and front arch to work with before building the platform for the anchor plate...I have heard that this area does get high heat, but I was planning on laying my flat ceramic gasket along where my entry meet my inner arch, and my rope/gasket doesn't have a way to stick, so my plan is to run a small bead to hold my rope up as I build my arch up...and if the caulk fails...no harm it was just there to hold the rope up as I press the brick up against the inner arch...I do have a question concerning the caulk though... UtahBeehiver, you suggested Kao Wool caulk, but I did find this stuff at my local Ace and not sure if it is inferior...the only thing reading it that catches my eye is that it is non-flexible... It sounds like it is rated for enough heat, but not sure about if I want something that has flexibility?

[UtahBeehiver]

Can't say if the Flame Stopper will work or not is not refractory based like KaoWool mouldable, I used UniExtreme but it is not available anymore. Also, I believe that Flame Stopper is for interior use only. Not knowing if you are just mounting the plate on top or placing bricks above the plate to secure the plate may make a difference on how you seal around the plate. PS we got 19" of powder last night at Snowbird..........

[edonovan]

UtahBeehiver appreciate you rubbing that in lol…yes I get all my powder day emails…it was definitely a late start to the season and fairly dry peak season and now everyone is getting dumped on…our other favorite spot (big sky) just got 11”
good points with it not being refractory mouldable and for inside…will order the kaowool product to be safe…plan right now is probably to recess my anchor plate in some bricks like your last picture and then probably 1 layer of brick over it to close it in…how would that change how I would seal around the plate?

[mongota]

For my build specifically, I thought of it as being more of a belt and suspenders type of approach.

I used high temp RTV to bed the anchor plate to the bricks. I thought of it more as a bedding compound and a gap filler rather than an adhesive. It simply sealed any gaps between the top surface of the not-so-smooth fire brick and the bottom of the slightly wavy metal flange of the chimney anchor plate. I also used four expansion bolts to tie the anchor plate to the brick. I didn't crank them down to where there was a threat of cracking a brick. I simply snugged them up, but firmly. The bolts held the flange of the anchor plate tight to the brick, helping to compress the RTV bedding between the brick and the anchor plate. Lastly I covered the anchor plate with a cast concrete capstone. THAT is what I used to lock the anchor plate firmly in place so it could provide a strong base for my exposed chimney pipe. The others (RTV and bolts) surely do provide assistance, but the weight of the capstone and how it captures the anchor plate as a whole was the key to a secure chimney in my build.

[edonovan]

mongota Thanks!! I think that is kinda what I had in my head…not too sure if I am going to try and mess around with any bolts or screws…probably just recess it in some brick and then cap it with some other decorative brick or something…
question for all…
1)is there a preference between vermiculite vs perlite on covering my insulating blanket?
2) is 10:1 the best ratio that most have used?
3) is this just the standard perlite/vermiculite that I would find in a garden center for planting?

had a little snafu with the front arch and needing a little sliver of a brick but oh well…”makes it more authentic” ♂️
home stretch!!!

[david s]

Dry loose perlite is a slightly better insulator than vermiculite, but as soon as you add cement to either it’s insulation value drops drastically so there’s no measurable difference between the two, even in a lean mix. I’ve heard of builders going as lean as 13:1, but 10:1 is as lean as I can go and still have it workable and resulting in it strong enough as a firm substrate to render against.
Even at 10:1 I add a little powdered clay to make it a bit stickier. Both vermiculite and perlite come in different grades. The coarse stuff requires less water but is not as workable as the fine stuff. I compromise and go for the medium grade, but now use a combination of fine vermiculite and medium perlite. Buying big (100 litre) bags from an agricultural supplier is way cheaper than the little bags from hardware stores.

[edonovan]

Thank you for the tips david s, was able to find a large bag of perlite at my local hardware store...it was up on a top shelf and I had to ask for it and the guy asked what it is used for...I said probably mostly planting and things like that...however...here is what I am using it for ...phone came out and all to show some pictures.

Pictures are where I am at for flue area and bricks my base plate are sitting in and cap bricks to hold plate down in addition to high heat sealant...really want to avoid putting bolts in the brick and think I can do that with the sealant and cap bricks.

New question for anyone...I plan on doing my ceramic blanket tomorrow...and have the rest of my chimney ordered and would rather make sure everything fits before mortaring bricks and cap bricks, sooo, is there a functional reason that I can't start drying fires once I have the blanket on? other than I will only have about a 6" "chimney" and it will smoke up my outdoor kitchen? Am I also going to get a bunch of smoke out the front due to not have "draw" and make the front real black? Just thinking I want to keep things moving but can also wait until chimney is in place if it will help that much more.