How to Repair a Crack in a Cinderblock Fence

Place the tip of a chisel at one side of the crack and tap it with a hammer to extend the edges of it out to a width of a quarter inch. Repeat the process along the entire length of the crack.

Brush the cracked area thoroughly, using a wire brush to remove any dirt and loose particles. Wipe the entire cracked area thoroughly with a rag soaked in paint thinner to remove all traces of grease or oil. If the cinder blocks are painted, apply paint stripper to remove the paint as instructed by the can.

Allow the wall to dry completely before proceeding with the repair. Any moisture inside the cinder blocks will interfere with the epoxy adhesion.

Mix the concrete epoxy repair mix as instructed by the packaging. The mix comes in two parts that must be applied in the proper proportions.

Mix sand into the epoxy, using a ratio of 5 parts sand for every 1 part epoxy. The sand makes the filler stiffer and works better for vertical cracks such as on cinder blocks walls.

Dip a trowel into the epoxy mix and scoop up an eighth of a cup. Start at the bottom of the crack and smooth the epoxy onto the surface of the cinder block until it fills the crack. Continue applying epoxy until the entire crack is filled. Smooth with the trowel and allow to dry according to instructions on the epoxy mix.