How to Fix a Cinder Block Retaining Wall

building a cinder block retaining wall
  • 2-4 hours
  • Intermediate
  • 75-125
What You'll Need
Putty knife
Stiff-bristled or wire brush
Mixing adapter
Bolt cutters
Cinder block

A cinder block retaining wall is often a better choice than a solid concrete wall, but it is not without their imperfections. When a concrete retaining wall settles, cracks can form, and the same is true with a cinder block retaining wall. The blocks are, after all, made out of concrete, but when they crack, it is usually the mortar. Over time, in the elements, the blocks that make up the cinder block retaining wall can deteriorate due to harsh weather conditions. This means that you will need to repair cracks and possibly replace entire cinder blocks. Follow the simple steps below to effectively repair a cinder block wall.

Step 1 - Out with the Old

To repair the cinder block retaining wall, you need to remove the damage. For a crack, use the brush to remove loose pieces of concrete and mortar. You want the site to be as clean as possible. If you need to remove an entire cinder block, the job is a little harder. Use the chisel and begin chipping away at the center of the damaged block. Remove as much as you can, and then carefully chip off the mortar from the surrounding blocks.

Step 2 - Remove Metal

rebar sticking out a concrete block wall

Once the cinder block has been effectively chipped away, you will notice rebar in the void that holds the retaining wall in place and held sturdy. This makes it impossible to place another cinder block and so you have to remove it. Cut the rebar as close to the top and bottom of the cinder block you just removed. This will not harm the stability of the cinder block retaining wall because the rebar is throughout the entire wall.

Step 3 - Cinder Block Retaining Wall Repairs

Consult the bag of mortar you choose to use for the manufacturer's mixing instructions and mix the mortar in the bucket. Use the drill and mixing attachment to mix the mortar. You want it to be the consistency of peanut butter. If you are fixing cracks, then place the mortar in a pastry bag and then fill the cracks with it. Use the trowel to remove the mortar that overflows.

If you are replacing an entire cinder block, you will need much more mortar. Use the trowel to place mortar inside the hole where the cinder block used to be. Make sure you cover every inch inside. Lift up the new cinder block, slide it in place and push it in hard. Mortar will flow out of the space. When this happens, use a putty knife to smooth it over the face of the new block. You can also fill the gaps with mortar using the pastry bag technique. If there is a lot of excess mortar coming out of the sides, remove it with a trowel.