Advice on a build - building a smoker inside a wall / hill side

onodle · Jul 7, 2017

Hi All

After a bit of advice I'm in the process of removing around 120ton of soil from my garden to create more of a usable space, to retain the top 3/4 of the garden I'm going to be adding a 2.1m high by 1.5m deep gabion basket retaining wall. I'm looking to make the most of that wall space as possible and I'll be building a pizza oven inside the wall / hill side and id like to add a hot smoker as well.

I know most of the builds I have seen on here and while researching all have vents at the back to allow air to come in, with mine id need to add an air event below the fire base do you think this would work or would I need to add another vent someplace? Only other thing I could think of was to add pipe along side that feeds below the fire with the vent above the high of the basket but not sure if this would draw enough air down? Or would it just act as another chimney?

So id be using fire brick and block with steel rebar to reinforce and then insulate around it and pack with cement around that would be hardcore with a blue pennant stone as the facing stone.

I'm just not sure the best way to draw air into the smoker or if I would just be wasting my time.

Happy to draw it up and provide photos :)

ahumadora · Jul 12, 2017

Draw a pic I am probably not the only one confused

onodle · Jul 13, 2017

Ahumadora said:
Draw a pic I am probably not the only one confused

Ok here you go so my idea is, to have a gabion basket retaining wall. I'll build a pizza oven and smoker inside that wall using steel and hollow blocks filled with rebar and concrete hardcore will go around them with a nice facing stone on the outside so my ovens are inside the baskets in effect making use of the 1.5m hillside rather than building into the patio area.

Rough sketch

rough plan.jpg

onodle
Jul 13, 2017

And for a visual of what I'm trying to do

for-visual.jpg

onodle
Jul 13, 2017

So I'm asking to get enough air in would I be fine with a front air vent as per my sketch or would I need to another another chimney at the top that draws air down into the fire place?

I'm not there yet in terms of getting ready to do this I'm about 40ton into a 120ton job

20170709_190311.jpg

onodle
Jul 13, 2017

20170709_190325.jpg

onodle
Jul 13, 2017

20170709_190351.jpg

onodle
Jul 13, 2017

Photo above is just me digging out the centre the left and right of the phot will be gone as well giving me 4.8m wide and a decking 8m deep rather than a uneven garden i can't use.

daveomak · Jul 13, 2017

Morning... I was just reading up on "hardcore"... It was suggested that no "lime rock", "limestone" be used as sulfating can occur... which can destroy your build...

Also, they are concerned with organic matter, any materials that may contain molds or mildew spores, rotted materials etc. as they will regrow with humidity and temperature sympathetic to their needed environment.... That "may"make any food stuff dangerous to ingest...

I would have those same concerns about the earthen material these "food ovens" would be surrounded in....

That being said, I really like the idea and the look it would afford.... Maybe a "waterproof vault" built into the area, that had ventilation where your ovens could slide in, with a façade, might provide the necessary precautions for food safety....

Dave

onodle · Jul 13, 2017

DaveOmak said:
Morning... I was just reading up on "hardcore"... It was suggested that no "lime rock", "limestone" be used as sulfating can occur... which can destroy your build...

Also, they are concerned with organic matter, any materials that may contain molds or mildew spores, rotted materials etc. as they will regrow with humidity and temperature sympathetic to their needed environment.... That "may"make any food stuff dangerous to ingest...

I would have those same concerns about the earthen material these "food ovens" would be surrounded in....

That being said, I really like the idea and the look it would afford.... Maybe a "waterproof vault" built into the area, that had ventilation where your ovens could slide in, with a façade, might provide the necessary precautions for food safety....

Dave

Thanks for the reply Dave, all the stone I'm backfilling with is Sandstone pulled from the very ground and planned on using sandstone again for the rest of the hardcore maybe with the od concrete block, brick and slab also. The internal oven build will have an outer hollow block skin with bat insulation around that and then heat bricks over the insulation. So in effect they get built inside the basket first with the back fill placed around them.

The baskets them selfs would be pours so water and id hope air could travel between them (or minimal air flow) to stop to build up of mildews etc (I've never seen it take shape on gabion walls - but there is always the first!) The lower basket will be 1.5m deep with the top basket 1.2m deep.

IF I could pull it off (i.e the build) do you think 1 air vent to the smoker below the fire would be enough or should I work out a way to add another? I'm considering a 10inch x 3inch intake vent and then a 6inch twin wall pipe for the chimney - I hope that would give it enough pull and draw to get the air moving inside?

onodle · Jul 13, 2017

Hopefully this helps also, so looking top down at it. Obviously I hope my mortar joins are a bit closer than that ;) ha

build-plan-2.jpg

onodle
Jul 13, 2017

kam59 · Jul 13, 2017

To answer your question on intake air. Yes the intake air under the coal base will work most vertical smokers are set up this way. Just allow yourself ample air intake, exhaust and opening into the cooking portion and she will be able to draft properly.

daveomak · Jul 13, 2017

Sounds like it would work.... About the air flow through the smoker.....

Because it is built into the earth, the interior of the smoker will "probably" be colder than the ambient air.... That will make the smoker not "draw"... You will need to heat the smoker above ambient for it to draw properly.... Easily done with a heat source... May take awhile to get it up to temp so it will draw, but worth it for the effect you will have...

onodle · Jul 13, 2017

Thanks both :) Yeah figured it would be ok and would need to get it going before it starts to work correctly! Just wanted to be sure before I start building as once its made it's not going to be that easy to get back at it not without pulling a few ton of stone away!

Few more weeks / months of digging and once work starts ill document and share. Can't get a mini excavator on site so it's all done by hand and on my own!

kam59 · Jul 13, 2017

Glad to help onodle. :)

I do not have a lot of experience in the earthen cookers like some here but I know what it takes to make a cooker draw. I look at an earthen cooker much like a steel cooker in the winter you have to let the steel heat up to get her to draw. Like Dave mentioned the cooker being the earth will take a bit to get up and may even sweat some during warm up so plan on maybe having a drip rail on the lower portion of the door to keep it inside and not on your stone.

onodle · Jul 13, 2017

kam59 said:
Glad to help onodle. :)

I do not have a lot of experience in the earthen cookers like some here but I know what it takes to make a cooker draw. I look at an earthen cooker much like a steel cooker in the winter you have to let the steel heat up to get her to draw. Like Dave mentioned the cooker being the earth will take a bit to get up and may even sweat some during warm up so plan on maybe having a drip rail on the lower portion of the door to keep it inside and not on your stone.

Oh nice tip thanks :)

Yeah I figured would need a fair bit to get it warm and started. I was concerned having all but one face more or less buried it would work.

Cheers

Gerry

ab canuck · Jul 13, 2017

This sounds like a fantastic plan / build, Really looking forward to how this will progress and workout. Great idea.....

ahumadora · Jul 13, 2017

For me a 10x3" intake would be fine. Thats about the size I run on my double door vertical smokers.

I usually leave the cooking chamber door open when lighting the fire and once the fire gets going well close it.

All that big cold steel does not want to draw, but after 15 mins it gets going and up to temp.

I would be more concerned out it rusting out in the dampness of the rock and dirt.

Maybe give it a few coats of red oxide( Get the brand that kills kids and dolphins)

onodle · Jul 14, 2017

Ahumadora said:
For me a 10x3" intake would be fine. Thats about the size I run on my double door vertical smokers.

I usually leave the cooking chamber door open when lighting the fire and once the fire gets going well close it.

All that big cold steel does not want to draw, but after 15 mins it gets going and up to temp.

I would be more concerned out it rusting out in the dampness of the rock and dirt.

Maybe give it a few coats of red oxide( Get the brand stuff kills kids and dolphins)

Thanks for the reply, no steel will be used on rebar to reinforce the concrete :)

onodle · Dec 30, 2017

Hi Guys

Making progress on this, after a run of bad health and weather I'm now 2.5m down in the main section (the deepest part) I'm about to dig back now where the smoker and pizza oven will sit. Quick question what is the most common 'internal' size for a smoker? IF there is such a thing?

I know I need to allow for my blocks, insulation and heat bricks and what's left is the internal section.

Insulation should I be going for 100mm bat? or would 50mm be OK or would you suggest a wool or some kind? I have soil back fill which I hope will help with heat loss.

Internal finish then are people using heat bricks or clay bricks?

I'm hoping to get it all dug out by end of Jan for the first foundation pour.

Thanks for the help :)

Progress photos to follow!

ahumadora · Dec 31, 2017

I wouldn't bother with mineral wool, maybe only for your main door. Lots of rock, brick then firebrick. Make sure you have ample drainage. Maybe dig a canal above it in the hillside to run off excess water.

Advice on a build - building a smoker inside a wall / hill side

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