How to Do a Retaining Wall on Top of Concrete Footings

Ensure that the surface of the footing is roughed up so that the mortar for the wall will bond to the concrete of the footer. Scratch the surface of the footer with your hand trowel when it is curing to roughen the surface. Mar the surface with an angle grinder if it is already in place by running the blade across the surface at least half an inch deep in criss-crossing grooves.

Mix up some mortar in your wheelbarrow according to the instructions on the manufacturer’s container. Different sized bags have different requirements, so add water according to your particular brand and size. Stir it with a shovel for a few minutes until you achieve a thick, creamy consistency.

Shovel at least an inch of fresh concrete mortar on top of the footing where your base layer of stones, bricks or blocks will be installed. Place your material on top of this layer of mortar. Space the pieces slightly so you have at least a half inch of space between them. Put mortar between the pieces with the mason trowel. Tap them slightly against each other and down into the mortar layer with the mallet and level to create a solid, level first row.

Apply more mortar on top of the first row with the mason trowel. Ensure you have at least three quarters of an 3/4 inch of mud on top of the first row. Repeat the spacing, filling of the joints and the leveling/tapping into place with the mallet for each subsequent row. Keep at least three quarters of an inch of mud between rows. Also check the wall for plumb with your level, and use the level plus the mallet to help tap the blocks into proper positioning.

Let the wall set up for at least an hour so that the concrete mortar doesn’t fall out of the joints when you finish them. Smooth the joints down with your mason trowel for a flat finish or use the hand jointer tool to contour the joints across the entire installation.