To lay a block wall, install the footing, mix the mortar and lay out the blocks, allowing 3/8 inch between each block. Snap a chalk line on the wall to use as a guide, and apply a layer of mortar on the footing. Apply mortar to the inside edge of the first block, place the block at the corner and set the second block in place at the opposite end of the wall. Continue laying blocks to finish the row.
The footing is typically a concrete slab that is installed below the frost line and is twice the width of the blocks. Refer to local building codes to ensure the footer and wall meet local regulations. When setting the block in place, apply a 3/8-inch thick layer of mortar on the end of the block, and a 1-inch thick layer of mortar between each layer of block. Fill the centers of the blocks with core fill grout.
To set the second row, apply a layer of mortar to the supporting block, and set the first block of the second row into place using the same process as with the first block in the first row. At the end of the second row, install a half-block.
Throughout the process, remove excess mortar with the trowel, and make sure each block is straight and level. After the mortar hardens slightly, use a jointing tool to smooth it.