Step 1 - Base Preparation
Remove all surface vegetation. Starting at the lowest point, dig a base trench the length of the wall. Base trench for a gravity wall is at least 18" wide x 7" deep. The base trench for a reinforced wall should be a minimum of 24" wide x 12" deep. Place, level, and compact a layer of 1/4"-to-3/4" base rock to support the first course. Average amounts are 4" deep for gravity walls, and 6" for reinforced walls. Check the entire length for level and adjust as needed. If you are building into a hillside, continue to excavate into the slope creating step-ups until you have reached the top.
Step 2 - Base Course
Starting at the lowest point, place blocks close together on top of the compacted base with raised front lip facing up and forward, checking the level and alignment of each block. Use a rubber mallet to modify where necessary to ensure a straight and level base course.
Step 3 - Backfill
Fill the cores and 6" to 8" behind the blocks with drainage rock. Then use on-site soil to fill the area behind the drain field, and fill any gaps in front of the base blocks. Use a plate compactor or hand tamper to compact the wall, drain field and area behind the drain field. Compact parallel with the wall, with the first pass directly over the top of the blocks. Continue to compact until the soil no longer settles. Check for level and adjust where necessary. Remove all debris from the top of the blocks to prepare for the next course. If the wall requires reinforcement, go to Step 5. If not, continue installing additional courses until the desired height is acquired.
Step 4 - Additional Courses
install the next row of blocks with an offset (stagger) of at least 3" from the course below. The vertical seams of the blocks should be staggered and not directly line up. Check again for level and alignment, adjusting where necessary. Fill the cores and drain field with drainage rock, using on-site soil to fill behind the drain field. Compact the wall and the drain field as before, with the first pass directly over the top of the blocks. Check for level and alignment adjusting where necessary.
Step 5 - Reinforcement
A typical wall is reinforced every two courses. This process should be started just after the first row of blocks has been installed, filled, compacted, and adjusted for level. Roll out the reinforcement grid behind the wall with the edge against the lip of the block. When placing grid along curving walls, the grid should always follow the back of the lip. To accommodate curves, slit the grid and either overlap it for outside curves, or feather it out to follow inside curves. When placing grid at corners, lay grid into the corner and cut it to fit. Place the next course of block on top of the reinforcement grid. Pull on the back of the grid to remove any slack and stake it in place. Fill the hollow cores and drain field with drainage rock, and use on-site soil to fill behind the drain field as before. Compact the wall and the drain field, with the first pass directly over the top of the blocks. Check for level and alignment, adjusting where necessary. Stack and backfill another two courses of block. Compact thoroughly, and rollout the next layer of grid.