Cinder Block (CMU) Offset Smoker

26,864

257

34

Posted

Introduction: Cinder Block (CMU) Offset Smoker

First Time Author Contest

Second Prize in the
First Time Author Contest

Home Improvement Contest 2017

Third Prize in the
Home Improvement Contest 2017

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.)

Share

Recommendations

  • Microcontroller Contest

    Microcontroller Contest
  • Science of Cooking

    Science of Cooking
  • Pocket-Sized Contest

    Pocket-Sized Contest
user

We have a be nice policy.
Please be positive and constructive.

Tips

Questions

26 Comments

I might have missed it... But what is the overall cost of this? Considering how much of a surface area this gives and how much room it takes up... If the cost is low this could be something everyone should do.

Craigslist is an excellent resource for cheap cinder blocks. Some people give them away for free even.

hahahah I didnt even think of that. hahahah Great build

It can definitely be done for cheaper if you have better resources and do a little more shopping around. But it cost me right around $330 total. The blocks themselves cost about $125. Having the expanded metal and steel plate lid cut to size were a large part of the expenses as well.

F.Y.I. ... you need to "season" any exposed cinderblocks; i.e. do several pre-burns to coat and seal their surfaces, BECAUSE the cinderblock material is toxic, and you don't want THAT on your meat. Just sayin' ...

Question: Are you burning the wood directly on the ground in the firebox?

Would there be any benefit to raising the fire up using a heavy grate or a rebar mesh in order to allow the ash to fall below?

Also, how do you dispose of the ash accumulation? Through the vent hole seems labor intensive in addition to digging out your sand with it?

I'm burning wood directly on the ground. I start with a bed of hot charcoal and ad the splits on top. I've found no need for grates as the fire burns nice and even.

I just use a an ash shovel to scoop out from the top (with the lid firebox lid removed). Takes about 5 minutes if that. It's hard packed dirt underneath. No problems at all.

A great tutorial! I'm going to drill a couple more heights for rebar holes so I can try that "whole pig" thing.

Now you just have to add a pizza oven on the end with a additional fire box and you have it all. :-)

Good day, very cool. My son and I are making plans to do this while my wife is on vacation with her sisters. No need to explain why this is the preferred time is there!