Smoker below oven? How to build?

[mstang1988]

All,

I'm considering builing a dedicated smoker in the area under the hearth of the oven. The basic design I was considering was an offset reverse flow smoker with an arch ceiling for the smoking chamber. Basically I want to take the corner design like http://www.fornobravo.com/forum/phot...2828/1_005.JPG and replace the fireplace with a smoker. The firechamber and exhaust will be in the rear of the structure and the loading area for the meat will be where the fireplace front is. I will have a steel door etc. My question is what is going to be my best method for building the hearth and insulating the smoker?

layers as following:

OVEN
INSULATING CEMENT LAYER
CEMENT LAYER
INSULATING CEMENT LAYER
CURVED FIREBRICK ARCH
SMOKER CHAMBER
SMOKER FLOOR
INSULATING HEARTH LAYER
CEMENT HEARTH

How should I suport the arched firebrick layer when adding all the weight above? Will this be able to support the weight onces curred (I assume a lot of the stress will be removed with the addition of the Solid rebar reinforced cement hearth layer of the oven). Do I need to poor the oven layer first and then build the smoker layer later? I'm new to masonry but I learn quickly. I was thinking the smoker might resemble the oven in this video (YouTube - Woodfired bread/ pizza oven construction) when it's all said and done. Basically take that, and create an offset portion in the rear (basically make it lower) then add some reverse flow characteristics to even out smoker temp and ensure the proper smoke temps etc. Would you go with loose insulation for this layer?

[cvdukes]

Re: Smoker below oven? How to build?

All,

I'm considering builing a dedicated smoker in the area under the hearth of the oven. .... My question is what is going to be my best method for building the hearth and insulating the smoker?

How should I suport the arched firebrick layer when adding all the weight above? Will this be able to support the weight onces curred (I assume a lot of the stress will be removed with the addition of the Solid rebar reinforced cement hearth layer of the oven). Do I need to poor the oven layer first and then build the smoker layer later?

Mustang,
I'm not 100% certain I understand how you're planning to build this. The smoker under the oven will be a dome inside (at least at the top) and the oven hearth will sit on top of it?
If so, you really have less concerns about it being able to support the weight of the oven. An arch is a very strong structure...a compound arch like a dome is even stronger. Many of the ovens that are built with wood storage areas under them are built with flat ceilings, and they are strong enough to support the hearth without any additional support in the center. By putting a dome in the inside of the underneath (now a smoker), it could actually give an extra point of support under the middle of the hearth slab:

Generally, smokers dont have the insulation like a pizza oven because they aren't anywhere near the same temps. You could get away without any insulation around it with just a minimal loss of efficiency. If you chose that route, the oven hearth supporting slab could just rest on the top of the smoker dome.
If you want the insulation, the construction sequence would be to build from the bottom... build the smoker walls vertical up to the height where it begins to dome, then build the lower dome. Once you get it built, you'll continue the vertical walls up to the height where they will support the hearth slab.
You can fill the space between the top of the smoker dome and the vertical walls with loose vermiculite or perlite fill...however, to get the extra support of the bottom dome, you'll need to cast a peice of vermicrete (or other semi-hard insulation concrete) on the top of the smoker dome. I would suggest cutting the top & bottom off a 5 gallon bucket to use as a mold to sit right on top of the smoker dome. Make it about 6-8 inches tall and pour your vermicrete in it. Basically, you'll be making a vermicrete column sitting on top of the smioker dome... once it hardens just cut the bucket off and fill the rest with the loose fill. Or you can just fill it all with vermicrete...use as little portland as you can get away with to keep the insulation value high.
I would also suggest using corrugated concrete decking metal as the support for the hearth slab when you pour it...or concrete backer board. You can even get away with using cheap tin as long as you get enough wire & rebar in the concrete hearth pour. All it has to do is support the wet concrete til it sets.
After that, build the top oven as normal: an insulating slab, the fire hearth and the dome, etc.

[mstang1988]

Re: Smoker below oven? How to build?

Mustang,
I'm not 100% certain I understand how you're planning to build this. The smoker under the oven will be a dome inside (at least at the top) and the oven hearth will sit on top of it?
If so, you really have less concerns about it being able to support the weight of the oven. An arch is a very strong structure...a compound arch like a dome is even stronger. Many of the ovens that are built with wood storage areas under them are built with flat ceilings, and they are strong enough to support the hearth without any additional support in the center. By putting a dome in the inside of the underneath (now a smoker), it could actually give an extra point of support under the middle of the hearth slab:

Generally, smokers dont have the insulation like a pizza oven because they aren't anywhere near the same temps. You could get away without any insulation around it with just a minimal loss of efficiency. If you chose that route, the oven hearth supporting slab could just rest on the top of the smoker dome.
If you want the insulation, the construction sequence would be to build from the bottom... build the smoker walls vertical up to the height where it begins to dome, then build the lower dome. Once you get it built, you'll continue the vertical walls up to the height where they will support the hearth slab.
You can fill the space between the top of the smoker dome and the vertical walls with loose vermiculite or perlite fill...however, to get the extra support of the bottom dome, you'll need to cast a peice of vermicrete (or other semi-hard insulation concrete) on the top of the smoker dome. I would suggest cutting the top & bottom off a 5 gallon bucket to use as a mold to sit right on top of the smoker dome. Make it about 6-8 inches tall and pour your vermicrete in it. Basically, you'll be making a vermicrete column sitting on top of the smioker dome... once it hardens just cut the bucket off and fill the rest with the loose fill. Or you can just fill it all with vermicrete...use as little portland as you can get away with to keep the insulation value high.
I would also suggest using corrugated concrete decking metal as the support for the hearth slab when you pour it...or concrete backer board. You can even get away with using cheap tin as long as you get enough wire & rebar in the concrete hearth pour. All it has to do is support the wet concrete til it sets.
After that, build the top oven as normal: an insulating slab, the fire hearth and the dome, etc.

Sorry for my bad writting before, was in a hurry like I am now. Seems like you got the gist of the idea though and yes, I am planning build a arched dome like the other non-pompeii bread ovens plans floating around. I'll just modify the design to my needs and build. My biggest question was typically the ovens call for using plywood forms for the bottom of the hearth while curing etc. How do I do this and support it with the structure(smoker) I have below? I can't use 2x4's like other builds so how do I redistribute the weight to the ground? Is it safe to put all that weight on my smoker dome or is that a disaster waiting to happen? Thanks again!

[cvdukes]

Re: Smoker below oven? How to build?

Mustang
Also throwing out a few pictures of my oven complex.

The pizza oven is at the top over the main smoker oven. The smoker oven has a fire box at the bottom in case I want to do hot smoking...build a fire below and it gets up around 350 degrees . The chimney for the smoker oven is off to the rear left side of the pizza oven. The ceiling of the smoker oven is flat...I don't have the skills or patience to try doming.
Further to the left, there is the big oyster roaster (the metal drum topped affair). It has 2 firebox doors. The big one just lifts off for the initial firing and after that, I just keep the heat going by feeding into the bottom fire box.
Smoke and heat from the oyster roaster circulate around the little flue pipe in the middle of the oven complex. I have a plug door that fits in the flue... its gets about 500 degrees in there...perfect for warming up french bread during oyster roasts. The heat also warms a metal plate under the roof overhang (where the spray bottle is sitting in pic 1)... I can keep a couple of pots of chowder warm up there. There is concrete board cover that normally covers the metal plate (I found its too easy to sit my hand up there without it)

The smoke from the oyster roaster also goes up the same chimney as the smoker oven, but I have a series of dampers in place so that I can shunt the smoke into the smoker oven first with the idea that I could do cold smoking. We tested this last time we fired up the oyster cooker to see if the smoke pattern actually works like I designed...the oven was about 180 degrees an smokey as the dickens...so now I just have to figure out how to manuver 2-300 pounds of pig into there ...(sort of tenatively planning that for Memorial day)

You'll notice that the pizza oven hearth is up very high...it actually hits me about shoulder height. It had to be that tall in order to accomodate the smoker oven. I like being able to see in it without bending over...but I've had to lift the shorter wives of friends so they can appreciate the pizzas cooking. Of course, the shorter guys are on their own to figure out how to look in.

The doors are all made of metal framed vermicrete with wood veneer exterior skin.

[cvdukes]

Re: Smoker below oven? How to build?

Sorry for my bad writting before, was in a hurry like I am now. Seems like you got the gist of the idea though and yes, I am planning build a arched dome like the other non-pompeii bread ovens plans floating around. I'll just modify the design to my needs and build. My biggest question was typically the ovens call for using plywood forms for the bottom of the hearth while curing etc. How do I do this and support it with the structure(smoker) I have below? I can't use 2x4's like other builds so how do I redistribute the weight to the ground? Is it safe to put all that weight on my smoker dome or is that a disaster waiting to happen? Thanks again!

Just figure that whatever you use fro the forms will stay in place...metal or concrete board. And using a dome suppurting the middle of the hearth will make that thing strong enough that you could roast an elephant.