How to Build a Cinder-Block BBQ Pit

A cinder-block pit is the backyard pitmaster's secret weapon for big cooks: cheap, sturdy, quick to stack and easy to take apart. Here is how to plan, build and run one for a whole hog or a load of shoulders.

How a block pit works

A block pit is a rectangular box of concrete blocks stacked without mortar. The meat sits on a grate laid across the walls, and a cover holds in the heat. Coals are made separately, in a burn barrel or fire, and shoveled in through the bottom of the pit in small amounts. It is a direct-heat pit: the meat is above the coals, but far enough away and with so few coals that it cooks low and slow, not seared.

Before you build

  • Check the rules. Some towns, HOAs and landlords restrict open fires. Check burn bans in dry weather.
  • Pick a level, open site on bare ground, gravel or pavers, well away from buildings, fences, trees, shrubs, overhanging branches, and anything flammable. The USDA Food Safety and Inspection Service (FSIS) advises a well-lit, well-ventilated area away from trees, shrubs and buildings for smoking.
  • Measure what you are cooking. The inside of the pit should be a little larger than your hog or your grate load, with room to shovel coals around it.
  • Size your grate first. The grate determines the pit size. Build the walls to fit the grate, not the other way around.

Materials

  • Standard concrete blocks. Count how many you need for each course (layer) around your rectangle, then multiply by the number of courses. Buy a few spares; some will crack with heat.
  • A heavy grate large enough to span the walls, made of material intended for cooking. FSIS warns against cooking on galvanized metal and other materials not intended for cooking because of chemical residues. Expanded metal and plain steel rebar or grates sold for cooking are common choices; avoid galvanized or coated metal.
  • A second grate of the same size if you plan to flip a whole hog.
  • A cover: a sheet of plain steel, or a frame covered with heavy foil. Do not use galvanized sheet.
  • A burn barrel (a steel drum with holes and a grate partway up) or a separate fire area to make coals, plus a long-handled shovel.
  • Heat-resistant gloves, a pit thermometer, food thermometers, and water or a fire extinguisher.

Building the pit

  1. Lay out the footprint. Mark a rectangle slightly larger than your grate's inside span. Clear grass and debris; a layer of sand or gravel helps level the base.
  2. Lay the first course. Set blocks end to end around the rectangle with tight joints. Leave a gap of one block at the bottom on one or both long sides; these are your doors for shoveling in coals. You can close them with a loose block between feedings.
  3. Stagger the joints. Each course should overlap the joints of the course below, like brickwork, so the walls are stable.
  4. Build to height. Most block pits are three or four courses tall, putting the grate well above the coals. More height means gentler heat; less height means hotter, faster cooking. Pick a height that suits low and slow cooking.
  5. Set the grate. Lay the grate across the top course. Some builders set a few pieces of rebar or steel across the walls first to support the middle.
  6. Add a final course (optional). One more course above the grate creates a lip that helps hold a cover and keeps heat in.
  7. Test-fit the cover and make sure it can be lifted off safely with gloves.

Running the pit

  1. Make coals. Burn hardwood such as oak or hickory, or light charcoal, in the burn barrel until you have glowing coals. FSIS advises using only approved starters, never gasoline or paint thinner.
  2. Preheat. Shovel a layer of coals into the pit and let the blocks warm up.
  3. Load the meat. For a whole hog, lay it skin-side up. Put thick parts, shoulders and hams, where you will concentrate coals.
  4. Cover and monitor. Place a pit thermometer at grate level. FSIS recommends keeping the cooker between 225 and 300 °F for smoking.
  5. Feed little and often. Add a few shovels of coals at regular intervals rather than big loads. More coals under the thick ends, fewer under the middle.
  6. Watch for flare-ups. Fat dripping onto coals can flame. Move coals out from under heavy drips.
  7. Check doneness with a thermometer. FSIS lists 145 °F with at least a three-minute rest as the safe minimum for whole cuts of pork or beef; meat for pulling is cooked well past that until tender.

After the cook

  • Let coals burn out completely and drench them with water. Stir and drench again.
  • Let the blocks cool fully before handling; they hold heat for hours.
  • Scrape and wash the grates.
  • Stack the blocks for next time. Discard any that have cracked or spalled.

Tips from the pit

  • Concrete can crack or spall when heated, especially if wet. Keep the blocks dry and stay back when the pit is first heated.
  • Wind steals heat. Set the pit where a building or fence shields it, at a safe distance, or plan to use more coals on windy days.
  • A tarp over the cover is a fire hazard. If rain threatens, rig a shelter well above and away from the pit.
  • Keep a notebook: time, pit temperature, and coals added. Next time will be easier.

Next: roast a whole hog, try an in-ground pit, or read about wood and fuel.

Sources

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