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How To Build a Retaining Wall

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Retaining walls are a versatile and flexible system to create functional and scalable landscape features. Retaining walls are effective for dealing with steep slopes, adding decorative rings around trees or creating a raised or terraced garden bed. Retaining walls can be built with or without mortar but one benefit of building a dry stack retaining wall is that they are less likely to heave and topple from the freeze and thaw cycle that is typical for Edmonton’s climate. Here’s how to build a retaining wall:

Tools Required

  • twine or mason’s string
  • stakes
  • chalk or marking paint
  • measuring tape
  • line level and level
  • wheelbarrow
  • spade and shovel
  • rake
  • plate and hand tamper
  • 2”X4”
  • stone cutter
  • rubber mallet and sledge hammer
  • chisel

Landscaping Materials Required

  • angular gravel
  • masonry sand
  • concrete stones
  • gravel


Planning & Design

  • When building a retaining wall, consider the space, location and length.
  • Sketch the retaining wall beforehand to get an idea of the overall design and placement in your yard.
  • Use the sketch to map out the space in the yard using a measuring tape.
  • Write down exact measurements on your sketch. Use a line level, stakes and mason string to mark the desired wall height.
  • Decide which landscaping products you will use to build a retaining wall. Rockland offers concrete stones in a variety of colours and sizes from Expocrete and Barkman.
  • Do an estimate of concrete stones required based on the desired wall height and size of hardscape material.
  • Determine the amount of landscaping materials required for the base. We recommend at least 1 inch of base material for every 8 inches of wall you intend to build.

Rockland Landscaping Supplies has a Materials Volume Calculator and knowledgeable staff to help you determine the required amount of landscaping supplies.

 Calculator


Excavation & Base Preparation

  • Before digging a trench, always remember to contact the utility company serving you in the Edmonton Area to ensure it’s safe.
  • To estimate the correct depth for excavation, consider the height of the retaining wall:
    • For walls that are 3 stack stones or less, dig a trench 3 inches deep.
    • For taller walls that use more than 3 stack stones, dig the trench 8 inches deep. Note: You will need to bury one row of stones below ground level.
  • The width of the trench should be approx. 12 inches wide depending on the stone landscaping products being used.
  • Remove sod and soil using a spade/shovel and wheelbarrow to haul away debris.
  • Use your measuring tape frequently to check the depth.
  • Use a vibrating plate compactor or hand tamper across the trench to provide a level surface to lay the stack stones.
  • Apply 2-4 inches of angular gravel using a rake to spread it evenly in the excavation site. Ask our staff at Rockland to verify how much landscaping materials should be used.
  • Use a plate tamper or hand tamper to compact into a solid base.
  • Apply 1-2 inches of masonry sand depending on the height of your wall.
  • Use a 2”X4” to smooth and level the surface using your level.
  • Tamp again until you have achieved uniformity right to the edges and proper elevation.

Retaining Wall Installation

  • If the retaining wall will be built on a slope, start at the lowest point.
  • Use your mason’s string and stakes as a guide to start placing stones side by side.
  • Use a level and rubber mallet to ensure stones are securely in place.
  • To cut stones to fit your space, mark the stone where it needs to be cut and score the stone with a line using a chisel and sledge hammer. Then pound the score line with the chisel and sledge hammer until the stone gently breaks a part.
  • Once the first row is complete, stack the second row by staggering the placement of the concrete stones to ensure the joints do not line up creating an interlocking pattern.
  • Optional: Apply landscaping adhesive or mortar to each level of stones until you reach the desired height.
  • Use a strong adhesive on the cap stone to prevent shifting.

Installation Completion

  • There will be an empty cavity behind the wall that will require back fill.
  • For walls that are less than 3 bricks in height, use the soil used during excavation and compact in 4-inch increments.
  • For taller walls, backfill with 6 inches of gravel for better drainage and top off with soil.
  • Spread sod or grass seed across the soil.
  • Your DIY retaining wall is complete!

Rockland has a large selection of concrete stones from Expocrete and Barkman plus Edmonton landscaping supplies and equipment rentals for your garden projects.


Please contact us if you have any questions and join our Facebook Group to get advice from our knowledgeable staff and landscape experts! Ask questions, share your experiences and your garden photos with us!