How to Lay Concrete Block in an Old Retaining Wall

Although concrete block walls are actually sturdy, sometimes accidents and natural forces may damage them. Retaining walls are among the most exposed to these factors due to the fact they have to bear huge pressures from the load that they need to hold in place.

Landscape Retaining Wall
Concrete Block Retaining Wall

In fact, the weak point of these retaining walls is mortar that holds together concrete blocks. When an excessive force is applied to a retaining wall, mortar layer breaks and concrete blocks can be displaced out of their place. The good thing is, repairing a retaining wall is not too difficult and requires no skills or special experience.

Material & Tools

  • – Hammer; Chisel; Wheelbarrow (Bucket); Masonry Trowel;
  • – Measuring Tape; Level; Hoe;
  • – Concrete Blocks; Mortar Mix;


1| First check carefully the concrete block wall and see where are gaps and take out any concrete block that may overhang these gaps where the missing concrete blocks were once. Use your hammer and chisel to break and remove the mortar layer that holds them in place. Every concrete wall row must have a wider gap than the one that is below it. In this way, you will have the possibility to work quite comfortably and also you will have enough room to apply a proper mortar layer to the joint.

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2| Mix up a small load of mortar with water according to the label directions, to a gel consistency. Mix the mortar manually into a wheelbarrow or bucket using a hoe. Do not use a cement mixer. For small batches such as those needed to repair your retaining wall, a cement mixer is not really worth the costs and all the trouble.

3| Using a masonry trowel spread a 1 inch thick mortar layer on top of the blocks placed at the bottom of the wall gap. Then start the top row setting the block into the layer of mortar on the right side of the wall gap, almost 3/8-inches to the left of the bottom block. If needed tap gently with your hammer into the concrete block until it has settled well and remove away the mortar excess with your masonry trowel. Use a level and make sure the concrete block is in line.

4| Apply mortar between the blocks and lay another one to the left. Proceed the same, laying concrete blocks along the wall gap bottom until you reach the left side of the hole. Then start another row on top continuing the same procedure, until the wall gap is filled.

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