I’m having a hard time leveling the first row of blocks on the base layer of gravel on my retaining wall. One piece of gravel can throw the blocks off. Can I use sand instead of gravel to level the blocks? -Kevin

To keep the blocks on your retaining wall level and structurally sound, you need a base layer of several inches of well compacted, sharp gravel. A handheld tamping tool can really help in getting the gravel level, but you’re right – one stray stone can throw off the entire operation!

Some block manufacturers recommend spreading a 1/2″ to 1” layer of sand on top of the gravel layer, to help with leveling. Be sure to use coarse builder’s sand, and tamp it down firmly to keep the sand from shifting and settling after the wall is built.

If you can’t get the sand tamped firmly enough, try putting a thin layer of fine (1/4” to 3/8” diameter) gravel on top of the coarse gravel instead. Fine gravel is more stable than sand but easier to level than the larger gravel underneath.

Further Information

• How to Build a Stackable Block Retaining Wall (article)
• Types of Retaining Walls for Your Yard (video)
• How to Cut and Install Retaining Wall Topper Stones (article)
• How to Build Retaining Wall Corners (article)
• How to Align Blocks in a Curved Retaining Wall (article)

Tags: , concrete block, gravel, retaining, sand, walls