Cinder Block (CMU) Offset Smoker

Intro: Cinder Block (CMU) Offset Smoker

For a small fraction the price of a heavy steel smoker, you can setup a large capacity cinder block version. Not only will it be cheaper it will be better insulated. Follow the instructions attached for a very effective, efficient and not bad looking unit.

STEP 1: Design & Dimension

Review design dimensions.

STEP 2: Clear Area

1. Clear appropriate sized area with offsets as needed.
2. Soften and level dirt or ad layer of sand.

STEP 3: Procure Cinder Blocks & Bricks

• Cinder Block: 8x8x16 (Qty. 60)
• Cinder Block (1/2): 8x8x8 (Qty. 15)
• Cinder Block (Caps): 8x2x16 (Qty. 16)
• Clay Brick: 4.5x9x1.75 (Qty. 24)

STEP 4: Base Layers

1. Place base layer of cinder blocks and use level to confirm flatness.
2. Alternate seem on each level.
3. Eliminate all air gaps.

STEP 5: Complete Firebox

1. Build firebox with rotated CMU bricks for air inlet and outlet as shown.

STEP 6: Complete Chimney Structure

1. With a chisel, break a 1/2 brick into half again so that the chimney has an opening as shown in picture.
2. Stack chimney to 3 blocks high for appropriate air draw.

STEP 7: Add Top Caps

1. Place top caps on alternating seems from cinder blocks underneath. (Top caps will ad a flat surface for lids to seal better)

STEP 8: Lid Construction

Lid Dimensions: 30.5" x 38" (Qty. 2)

1. Cut plywood to dimensions.
2. Procure Heat Shield Insulation (4 ft x 6 ft) and cut to same dimension as plywood.
3. Using a staple gun, apply insulation to bottom side of wood.
4. Fasten two lid pieces with hinges in middle and and handles.

STEP 9: Add Clay Bricks

1. Line the inner firebox with clay bricks for extra heat protection for the concrete blocks.

STEP 10: Rebar Grate Support

1. Measure off alignment for rebar supports. (3 places)
2. Using a 1/2 inch concrete drill bit, drill holes through only one side of blocks.
3. Insert 25" long, 3/8" rebar.
4. Procure or cut, 3/4" X 13 ga. flattened expanded metal sheet to 22" x 53"
5. Place expanded metal on top of rebar for a cook grate.

STEP 11: Fire Box Lid

1. Procure 29" x 31", 3/16" thick carbon steel plate.
2. Drill and bolt in handles for easier removal (not shown)

3/16 steel plate is necessary for firebox as temperature here will be too extreme for thinner materials

STEP 12: How to Use

Now you're ready to test it out!

• Use a left over block as a damper for your incoming fire vent. Slide back and forth to adjust heat.
• Leave stack vent open at all times.
• Add another expanded metal grate over the fire-pit if you would like the option to grill over the fire. (Good for tri-tip and chicken)

(This specific pit has about a 20 degree difference from one side to the other....which is actually very impressive.)

Comments

[johneriv70]

Would like to build this for a cooking surface that is 36x94. Looking to do some pop up and fundraising. Can you help me as far as calculating the materials needed?

[shsdawgs]

I built this smoker a month or so ago. There is a learning curve with fire management. Here are a few tips that I have discovered and feel are helpful:
1) Make sure the first layer of block is level and square.
2) If possible, have the metal shop weld on a couple of handles. It’s worth the extra couple of $$.
3) Invest in a good pair of welders gloves.
4) I found it was easier to get up to temp and control the temp by removing the top course of large blocks from the fire pit. This allows the heat to vent more efficiently into the cooking chamber and you will need a smaller fire.
5) For the cook box, get a couple of cheap oven thermometers (less than $5 each) and place them right on the grill. Much more accurate temp.

[joed33]

Anyone build this with mortar? I'd like to build this in a more permanent way. Thanks

[bradbraden4]

This type of smoker works like a champ!!! After making some small modifications to my first build it tore it down to use those blocks for a semi raised garden bed. I made it about a month and couldnt handle not having my smoker so today I picked up a truckload of nice, new block for the third, hopefully permanent, build! A couple modifications I made that may give some ideas to folks were, in addition to lining the sides, to dig out the firebox about 1ft. and lined the base with some spare red kiln fired brick. That gave me about 6in. more depth and really held temp. without burning through my wood. I also added supports close to the chimney to hold my lid upright when opened and installed a thermometer both toward the front and back. The most useful addition was to extend my cookng grate 8in. beyond the smoke chamber blocks on one side to give myself a nice shelf. As for the heat shield, I lined the underside of the plywood top with aluminum tape and it worked wonders. I love seeing ideas/builds like this and everyones tweaks that make them unique so keep 'em coming!

[chrisprras]

Has anyone sealed the inside with additional cement to slow smoke leakage? Additionally any rec on placing 2 temp gauges on the smoker side of the offset giving the 20 degree variability. Ty!

[scottcofield]

Where can I purchase the heat shield from?

[jason_5hundy]

I actually found the heat shield really wasn't that necessary, jut wood or metal lids are sufficient. But what I used was an automotive fire insulator. Most online auto stores sell it.

[bryangoodell]

I'd like to double the size for commercial output- Can you help me?

[jason_5hundy]

I'd be happy to. Email me at [e-mail] and let me know more about what you're thinking.

[Peterjohndendulk]

Here from south africa. I built this awsome desighn a bit more permanent. We have done everything from ribs to baking breads. This build is awsome ill he tiling it next week

[mikelandrum]

I am having a hard time finding the clay bricks in these dimensions. Any suggestions.

[natecrooks20]

these are standard size blocks at lowes home depot etc

[Haus2005]

I have been wanting to do this for a long time. Im just gonna have to figure out the math and scale this back a little. Definitely dont need one this big.
This is fantastic though!! Great work!!

[stephen.dobek]

What insulation should I look for? I wasn’t sure I was finding the right thing at Home Depot. Hard to tell if something is food safe or not.

[rathomas80]

I think he said clay bricks to help with insulation. unless you were talking about the insulation on the lid. I'm about to start mine how long did it take you to create your brick smoker?

[Rhk0862]

Hi I am almost finished with my smoker build. I am curious can I use any kind of insulating heat shield? Are there concerns that material like this might contaminate the food? Where would be the best place to get the material from Home Depot/Lowes or Auto parts store?

Rick

[amkucera]

Hey love your build. Building it this weekend. One question, where can pick up the thermometer you used? I looked all over Amazon and didn't see it. Thanks!!

[jason_5hundy]

It won't let me post the link on here, but look under "Remote Reading Panel-Mount Thermometers".

[amkucera]

Great! Thanks for the info. Much appreciated! Do you find they work well/accurate?

[jason_5hundy]

I bought it on Mcmaster-Carr a while ago.