A concrete block barbecue is a great outdoor addition that can provide an easy-to-use grilling and food preparation area. The removable grill and counterboard of the design allow for easy cleaning, and the open pit nature of the project enables you to slide a coal tray right into the structure, grilling over an open fire. Construction of a concrete block barbecue takes basic bricklaying skills, as well as some experience with pouring a concrete slab. The design is versatile enough that you can size it to fit your needs.
Choose a grill and counterboard that you wish to use as your barbecue surfaces. The counterboard is the surface your food can be prepared on, or sit on for easy reach. Choose a counterboard made of a tough durable material, such as wood or laminated pressed fiberboard. Measure both items noting down the measurements.
Dig the foundation area for your block barbecue. Excavate a space that's the combined size of your grill and counterboard plus 24 inches in length and eight inches in width. Make the foundation hole four inches deep.
Mix the concrete according to the manufacturer's instructions in a wheelbarrow using a spade. Pour the concrete into the foundation hole to act as a footer for your barbecue. Level the poured concrete out by dragging a wooden screed stick across the surface. Go over the surface of the concrete with a concrete float to smooth the surface and drag some of the moisture in the concrete to the top. Cure the concrete for three days, wetting it daily to prevent it from drying out too quickly, while allowing it to harden enough to lay the blocks.
Arrange the first layer of blocks on the surface of the concrete to find the best placement pattern. Lay the blocks so that they form an "E" shape on the foundation, with a single row of blocks on each end of the barbecue and a row in the center to separate the grill pit from the countertop surface. The open end of the "E" for the grill pit should be large enough to place your grill while the end of the "E" that will contain your countertop should be large enough for the board. Leave at least two inches on the concrete foundation surrounding the block placement. Mark the block placement and then remove the test layer.
Mix the mortar and lay a 1/2-inch layer of the mortar on the foundation along the chosen block line. Lay the blocks, beginning at the corners of the barbecue, and stagger all vertical joints to a half-brick width. Tap the blocks into the mortar bed to place them, and check the level of the first layer of blocks using a carpenter's level.
Place additional layers of blocks. Use a trowel to spread mortar in the layer between blocks and the joint between the blocks. Check the level of the block placements for each layer. Tap the blocks with the end of the trowel to level them in the mortar. Continue laying the blocks until you've reached the height at which you wish to place the grill and the counterboard.
Install the grill and counterboard supports by placing galvanized lag bolts into the mortar with an exposed inch extending into the center of the barbecue. Place a bolt every five inches surrounding the area for the grill and counterboard. Continue to place blocks atop the bolts, holding the bolts in place with the combination of the mortar and the block placements. Lay the blocks until you've reached the desired barbecue height.
Allow the mortar to dry completely according to manufacturer's suggestions. Place the grill and counterboard in place atop the lag bolts to complete the build.