Ope-dog's 36" Oven .. (fingers crossed!)

[Neil.B]

Yes, I'm including a smoker that will be heated by my chimnea. I haven't decided what type yet as I'm still learning about smokers. It will be about 30" wide x 30" high, I haven't decided on the depth. I could do it 30" or make is thinner and would allow a shelf in front.
I've seen some doors on ebay that I like that are 24"x24", but will cost about £200 inc delivery. My build has been very cheap so far so I might treat myself, but then think I could buy some steel and make my own...tooooo many decisions

[Ope-dog]

@Neil.B... the smoker has been built (albeit not 100% finished...) and I used an "offset" design. No surprise, I had decided to just do a *small* little smoke chamber on the end of the BBQ island for the occasional cut of this or that. Quickly got hooked and now I'm really bummed that I can't get more than 1 brisket in at a time. So with all this in mind, I'm trying to not sell myself short on the pizza oven as I'm sure I'll want to utilize it for breads, roasts, and what-not as many others do. If I recall, aren't you incorporating a smoker into your build as well? My fire box sits down at the end of the BBQ island and the smoke chamber is incorporated inside the island. I have learned this design is a bit flawed, as whenever I lift the lid to get to the smoke chamber you get a face full of smoke..

For the doors, I couldn't get a machine shop around that was willing to take on my small project (presumably not worth their time..) so I just ordered a few metal plates (A36 stainless) and fashioned a few handles in to them.. then painted them black with a high temp paint and ordered some welder gloves to sling them around. Seems to work pretty well.. holds a smoke around 225-250 F pretty consistently and have had a few great smokes. The colder, wetter weather is proving to be a challenge for sure when it comes to getting the smoke chamber up to temp vs on a nice, hot summer afternoon.

So the trick will be to fashion a door for the pizza oven that matches the smoker. I'd like the outside appearance to be the same stainless with handles on it.. I have a buddy who claims to have a plasma cutter so I'm guessing I can get another sheet and have him cut it down to fit my inner arch. How I go about insulating it is still in the works. I'm sure the forum will have plenty of ideas/feedback. I also need to finish off the chimney for the smoker, however I'll be cladding it in the same finish as the pizza oven. so that will get built up at the same time.

Attaching a few pics of the smoker / doors for your perusing. Someone on here built a pretty large pizza oven / smoker combo. It's a fascinating thread. And his build turned out quite great! Highly recommend the read...

[Neil.B]

I originally planned on a 36" but miscalculated the hearth/insulated walls, so scaled down to a 32".
The good thing about making it smaller is i only used one 25m roll of insulation to give two layers.

what doors are you planning for your smoker and what type of smoker are you building?

[Ope-dog]

Funny... it looked larger on paper for sure. Now I am thinking I will need to scale back to a 32" ID to be able to accommodate all the intended insulation and outside shell. But I don't expect a 32" down from a 36" will be too noticeable?

It's ironic how the pizza oven was an after-thought to compliment the smoker. The smoker was a last minute design to compliment the BBQ. And I had planned on a pizza oven that was small, simple, and able to fire a few 8" pies from time to time. Once I got into this site and saw how amazing the pompeii builds have been... just couldn't see doing it any other way. Makes me wonder what the next "compliment" will end up being to this growing monster. LOL!

[Neil.B]

Looks great, surprising how much bigger it looks.

[Ope-dog]

Concrete counter poured this last week. Hope to get going on the base later this week and setting bricks soon after!!!!

[Ope-dog]

Hello Forum... a home-brew question that perhaps someone can help out with:

A local pottery supplier in PDX has recommended "lincoln 60" as they fireclay when people call looking for it. She asked if I was building an oven or cob stove, so I figured this was a pretty safe bet. Any thoughts, or has anyone used this before? Many of their clays seem to contain sand, which I suspect would skew the ratio in unwanted ways. She claims this brand does not have sand in it.

Also, I have read in other places that the sand used in home-brew should be a fine grain, like a pure silica, (commonly found at a pool supply store ) and not beach sand or coarse sand. I've then read conflicting info that a builder's sand or mason's sand works fine as well. I can only surmise that a coarse sand wouldn't allow everything to mesh and bond as well, however I'd think all the edges and cavities on a coarser sand would help stuff grab. What is most desirable?



As always, I welcome any feedback!!!

[Ope-dog]

Mongo, I agree.. seems like coating the top of the cement pad, along with the sides of the insulation board would be all that is required to keep things dry. I will aim to do that prior to getting started with the build.

One more question at this stage... what type of saw did you use to cut your CalSi board? I plan to go with one layer of 2" board..which isn't as robust as yours but should do ok for my needs, I believe.

Thanks!

[mongota]

I was thinking to put red-guard down over my insulation board like you did on yours. Are you able to provide me with any feedback from this practice? Does it seem to work as intended... or not useful? I've heard when the CalSi board gets wet it is a bugger to get dry.. so the idea of "guarding" seems to make a lot of sense in theory.

Thanks again!

I put RedGard on the top surface of the dome slab, and then placed the 4" of board insulation on TOP of the RedGard coated slab. I then painted the exposed outside edge or perimeter of the Insulation, lapping it down on to the RedGard already on the slab, to seal that outside insulation/slab corner.

It has worked very well for me. My reasoning for this was that the "round footprint" of my finished and watertight dome sits on top of a much larger and non-waterproof square concrete slab. When the exposed surfaces of the slab that are not covered by the dome see rain or snow, the slab could absorb moisture and saturate, and I did not want moisture wicking up in to my floor insulation from the moist slab below. The RedGard acts as a protective barrier. I will say that since I've completed by shell, even when the slab has puddles of water or standing snow, the insulation has always stayed dry. So I'm happy using the product as I did. There are alternative methods, it's simply the one I chose.

Were I enclosing my dome in an enclosed house-like structure with roof overhead, I'd think the RedGard unnecessary. But for my design, I felt it good insurance.

I ran tests the first year the oven was in use, the RedGard underneath the insulation never saw temps higher than the upper 90'sF. I think the highest measured was 98F.

For clarification, I would NOT put RedGard on TOP of my floor insulation, between the floor insulation and the firebrick. It would see much too high temperatures and degrade, and likely stink the place up.

[Ope-dog]

Hi Mongo... this is GREAT information. Exactly the tips and tricks I was hoping to get back from the forum. Thank you for taking the time to give me your perspective and lessons learned.

I am with you on idea of waiting for a warmer day to hit it hard. That is certainly the intent. And building the foam box is actually a pretty novel thought. I just may look into that vs. the blankets and plastic. A 50 degree day is fine for pouring cement (like I had yesterday..) but when you're not moving too much and working with wet mortar in one spot, it can become a bit more obnoxious, I've found. My goal is to do as much prep under cover (and in comfort) like you suggested and hope the weather stays pretty tame over the next month.

I was thinking to put red-guard down over my insulation board like you did on yours. Are you able to provide me with any feedback from this practice? Does it seem to work as intended... or not useful? I've heard when the CalSi board gets wet it is a bugger to get dry.. so the idea of "guarding" seems to make a lot of sense in theory.

Thanks again!

[mongota]

Does the home-brew do ok in temps ranging from 40-55 degrees F?

As you know, hydration and cure times are lengthened, and early strength is reduced, as temperatures go lower. Below 40, I don't recommend any DIY mortar work. Above 40 is okay. Above 50 would obviously be better.

If it were me?

I'd watch the weather and try to kick arse on a warmer day. Use the too cold days for prep; cutting your next set of tapered bricks, etc, in preparation for the next warm day and not-so-cold night.

A couple of ideas, if you bring your bricks and home brew ingredients inside (or at least that day's use of materials) so they are warmer, at room temp, versus 45 degrees, that can help. A little. Try to do your work earlier in the day so the first few hours of curing are in the warm afternoon. At night, an easy DIY thing is to cover the dome with several thicknesses of moving blankets and sheet plastic. The cover will help insulate and retain the warmth from your heating light, the plastic will prevent the cold night breeze from air washing through the moving blankets. Do monitor the interior dome temps. You may be surprised at how high the temp inside a dome can go just from the heat of an incandescent or halogen work light or light bulb.

I helped a friend through the same issue, we used a few sheets of 2" XPS to build a big foam box to go over the project when it wasn't being worked on.

Bond strength is slower to develop in colder weather. It's not something to be afraid of, you just need to acknowledge it and be careful you don't knock an already set brick loose when setting later ones.

[Ope-dog]

So.. after much time passed I was all geared up to pour my counter slab yesterday. Unfortunately, I had a few mates over to first pour a larger slab for my tractor implements. More cement got used than I anticipated for that project, and.. well.. I didn't have enough on hand to pour the counter. So now I'm delayed yet another week until I can get that poured. My insulation board and blankets arrived from FB on Friday and I'm anxious to get going on this build.

I have a few questions moving forward that maybe some folks can help out on...

Living in the NW, we are pretty much into the cold, rainy season. I've resigned to the fact that I'll need to build a canopy over the build site and that's ok. But with high temps now not getting out of the 50s, and low temps will soon be flirting with mid 30's, I was curious if anyone has continued to build in such weather conditions? I can cover the dome as I build and keep a light in there at night to keep mortar joints from freezing. Does the home-brew do ok in temps ranging from 40-55 degrees F?

It will be very disappointing if I'm unable to make any progress on this beast before next April. No real snow or heavy freezes happen up here.. but it's a long, wet, cold slog for sure.

[mongota]

Scott, yes, carrying the buttress down to the slab is what I was offering as an option so the weight of the chimney would bear on the slab and not the insulation.

Firebrick splits are used for fireplaces all the time. I'd venture they could be used to create the flue liner for a chimney? Half the thickness, half the weight? And the dimensions lend nicely to a roughly 7-3/4" square flue. I'd let others chime in on that.

I certainly understand the desire for the exterior aesthetic to match the other features of your outdoor space.

[Ope-dog]

Hey Gang,

First off, I appreciate all your input. I know there's a lot of threads going on and a lot of builds to weigh in on ( covid has no doubt given a lot of people time to work on their WFOs, I suspect..) so I really appreciate your insight on my question. Certainly Gulf, your chimney is a force to be reckoned with and top notch, so it's good to have your opinion. And Ricky, you basically echoed my exact thoughts.. if the fire brick can handle a 700+ degree fire, I can't imagine the chimney would have any issues. But as you and Mongota bring up, ... the weight.

I'll be perfectly blunt... I like the look of a brick chimney better than a SS or metal flue. It's just a personal preference. And as I'm trying to tie in the look of this with my existing BBQ and smoker (which I still haven't finished the chimney on that yet, either..) the brick look is ideal. So.. it sounds like a few options are on the table..

1. Build the entire thing out of fire brick.. then clad with the matching brick veneer. = HEAVY!!!!
2. Use a metal flue pipe, then clad the metal flue pipe with brick veneer. = NOT so heavy.. maybe a bit more pricey
3. Mongota's idea..which is brilliant and one I had not considered! = a BIT heavier than option 2. MUCH more affordable. 3. More labor intensive and potential for the flues to crack and be back to options 1 or 2 anyway...

To address the weight issue on the isulation base, Mongota.. I hear what you're saying and that makes sense. I'm wondering if I were to buttress a bit on the sides as you're proposing, I could then tie in the 2 "columns" a few rows up which, in my mind, would thus lend support and weight distribution at the same time. Regardless of what above option I end up going with, I appreciate your suggestion as in my mind I'm thinking that will have a nice, robust look to the front of the oven. I've included a quick sketch-up and maybe you can let me know if that's what you were also suggesting?





So after reviewing the sketch, I guess the real question is how much weight I want to have on the front of my base stand? I know I want the finished product to be a brick that matches the existing BBQ. Those cannot be exposed directly to the heat of the chimney. I am thinking that there is no upside to sticking with the firebrick for the entire chimney. I believe between the weight and thickness, it will not be worth the $50 or so difference in buying a metal flue and covering it up.

Sounds like option #1 above is the least desirable after review. Any feedback from the forum is ALWAYS appreciated!


- Scott

ps. In case anyone is wondering, the above scale is 1 square = 1 foot, but it's all a ballpark mock-up for the sake of this chimney discussion... :-)

[mongota]

If I was going to incorporate a 100% masonry chimney with stone cladding on my build, the one significant thing I MIGHT have done differently is I would have CONSIDERED cutting away the 4" thickness of under-floor insulation that currently sits under my vent tunnel bricks (which support the chimney) so the bottom courses of vent tunnel brick, and thus the weight of the chimney itself, would bear directly on the concrete slab and not on the 4" thickness of floor insulation.

With a heavy masonry chimney built directly upon the board insulation I'd have been worried about potential insulation compression from the weight of a masonry chimney.

On the flip side, for a heavy masonry chimney the vent tunnel arch underneath a heavy masonry chimney may require buttressing to prevent lateral spreading and collapse of the landing tunnel. The bricks added by buttressing will increase the footprint of the arch tunnel that sit upon the insulation, and thus decrease the weight per square foot of the chimney on the insulation, reducing the potential of insulation compression. If sufficient, the floor insulation COULD be left intact and the masonry chimney with the larger footprint built directly on top of it.

All told? It's something I considered but did not pursue.

Tangent: If you really want to use the 8x16 flue on an outside oven, since you'd want a precise cut you could use an angle grinder with diamond blade to take an 8" wide strip out of each 16" wide side of the flue. Bring the two 8x4 "U" shaped remnants together for an 8"x8" split flue. Or cut a 9" strip for an 8"x7" flue. Etc. Homebrew mortar the flue joints as you build your chimney. If you use more than one length of flue liner while going vertical, offset the cuts by 90 degrees as you stack the liner.