How to Install a Cap on a Curved Retaining Wall

Building a retaining wall in your garden or around your landscape serves multiple purposes, providing a decorative addition, an efficient border that keeps soil in place while allowing moisture to drain through, and even additional seating around your patio or barbecue area.

Capping off these retaining walls helps to add a decorative finish, as well as prevent weed growth through the wall and a stable support system in case someone does sit or stand on the wall. The caps can be tricky to install on a curved wall, however, as the cap pieces are generally stone blocks, but careful cutting will ensure a firm and decorative top to your wall. .

Set a cap stone piece on one end of your retaining wall. Center the piece on the top of the wall. Because the wall is curved, the cap piece may overhang the wall in some areas.

Trace the outline of the wall onto the cap stone piece with a mason's crayon. Run the crayon along the bottom of the cap piece against the wall on both sides. This creates a tracing of the wall on which the cap has to sit for proper coverage.

Set the cap stone piece face down on the table of a diamond blade wet saw, so that the marked lines are facing upward. Line up one of the markings with the saw blade; this type of blade is specifically designed to cut through stone.

Don protective gloves, goggles and a dust mask when cutting stone to protect yourself from damage. Activate the saw and slowly cut through each marking line in turn, shaping your cap stone to the exact curve and shape of the wall. Continue until you have shaped the stone.

Use a chisel and hammer to shave off any sharp edges or to smooth out corners where the straight saw could not follow the curve of the wall. Carefully score and chisel along the edge of the cap stone to create the finer curves of the wall's shape.

Set the cap stone back onto the wall to check the fit. When you have the stone completely cut and chiseled to shape, remove the stone again.

Spread two thick beads of landscape block adhesive over the surface of the wall where the cap will sit. This will hold the cap in place and allow it to better support weight.

Place the cap back in place over the adhesive and gently wiggle it to help it bond to the landscape adhesive. Repeat the measuring, cutting, chiseling and gluing for each cap block until the wall is complete.

Things You Will Need

  • Cap stones
  • Mason's crayon
  • Diamond blade wet saw
  • Protective gloves, goggles and mask
  • Chisel and hammer
  • Landscape block adhesive


  • If you don't own a diamond blade wet saw, rent or purchase them from equipment providers or hardware stores.
  • For a different decorative touch, consider overlapping the edges of the caps by an inch on each edge. This is a design detail that is completely up to you.

About the Author

Samantha Volz has been involved in journalistic and informative writing for over eight years. She holds a bachelor's degree in English literature from Lycoming College, Williamsport, Pennsylvania, with a minor in European history. In college she was editor-in-chief of the student newspaper and completed a professional internship with the "Williamsport Sun-Gazette," serving as a full-time reporter. She resides in Horsham, Pennsylvania.