Retaining wall caps not only enhance the structural integrity of a wall but also provide a polished, professional appearance. Proper installation techniques, like cleaning blocks, using high-quality adhesive, and ensuring level placement, create a durable and visually appealing result.
Retaining wall caps have two purposes:
Retaining walls do not need a cap to function, however, the look of the wall when caps are installed far outweighs the cost of labor and materials to do this step.
Walls that are left “unfinished” and without a cap do not look as good as a finished wall.
If you ever see a retaining wall with caps that are out of alignment, falling off, or missing, this is a good indicator that when the caps were installed either the blocks were not cleaned off before caps were placed, not enough glue was used, no stringline was put up as a guide to ensure the caps are placed on straight, or each cap was glued and placed one at a time. (If this is done it is hard to go back and make changes to the caps if they need to be cut).
The first step to installing caps is to clean off the blocks and make sure that they are free of ice, snow, leaves and debris. Once the block is clean, all of the caps are placed on the wall before gluing to ensure that each cap will fit. If a cap needs to be cut, this is the time to do so. Then it is time to glue the caps on!
We like to use PL Premium glue because it gives us enough time to glue the caps, place them, and adjust the cap if needed to ensure that everything is even and straight. Once caps are placed, the wall is backfilled the next day to ensure that the glue has cured and that the caps do not move.
If you need the retaining wall cap to cure faster, a glue called Techniseal structure bond sets up in minutes. Just remember that once a cap is placed with this product there is no adjusting it.
Caps can be placed either forward for an overhang look, or can be pushed back (even with the front of the block).
A step that most contractors do not do when placing the retaining wall caps is using shims to get the top of the caps as flush as possible. When caps are made, they are not all the same thickness and shims help level the caps out, making them even. This step takes extra care and time, but makes a world of difference in the appearance of a retaining wall.
From a structural aspect, retaining wall blocks do not need to be glued together. Blocks are dry stacked on top of one another rather than glued because we want the wall to be flexible and move with the seasons (Frost).
The exception to this rule is corners and step downs. Corners are built using smaller blocks, so gluing the blocks together can prevent them from moving in time.
If a retaining wall has stepdowns (when the wall gets shorter in height), it is common for people to step/walk on the wall, so gluing the block can prevent it from moving and rotating and causing harm to the wall or a potential injury.
While retaining walls serve their purpose of retaining soil, they can add a stunning focal point to a yard, and all of these details of craftsmanship contribute to a wall that can do just that.