How to Build a Footing for a Retaining Wall

Sloping sites in the landscape can make it difficult to establish and care for turf or ornamental plants and often lead to unsightly and environmentally-damaging erosion. One option is to install a retaining wall in the landscape. Retaining walls can control erosion while creating landscape interest. Homeowners can often construct short retaining walls of dry stone, timbers, blocks or bricks without professional expertise, but municipal codes often regulate wall construction. One key aspect of retaining wall construction is building the footing, which must support the weight of the wall. Dry-laid stone walls do not require a footing, but walls of block or brick do.

3/4-inch thick boards
Stakes
Nails
Hammer
Measuring tape
String or line
Spade
Shovel
Level
Concrete
Wheelbarrow or cement mixer
Trowel

Instructions

- 1
  Ensure that the site is suitable for footing and retaining wall construction. The soil surrounding the footing should be firm, well-drained and free of tree roots and drainpipes. If the wall could eventually be impacted by tree roots, consider installing a root barrier or deflector between the footing and the tree.
- 2
  Calculate the dimensions of the footing that will be required. The footing should be at least twice as wide as the planned wall with a depth at least equal to the wall width. The suggested minimum footing depth for walls less than 3 feet tall is 8 inches. The bottom of the footing should be below the frost line and at least a foot below ground level.
- 3
  Set up form boards, which can be made by nailing two wooden stakes into a thin board of lumber, at each end of the planned trench. The footing trench should extend a foot beyond the planned wall.
- 4
  Mark the width of the planned footing trench on the top of the form boards and drive nails where the front and back of the trench will be.
- 5
  Stretch a string or line between the nails. The string and form boards will mark the outline of the trench.
- 6
  Use a spade to mark the ground along the edges of the trench outlined by the string then remove the string.
- 7
  Excavate the trench with a shovel. Keep the sides as vertical as possible. The trench should be deep enough to accommodate the footing and at least a layer or two of the wall-building material.
- 8
  Check to make sure that the bottom of the trench is level with a long board and a level.
- 9
  Drive a wooden stake into the bottom of the trench near one end of it. Drive it in until the top of the stake marks the top of the footing.
- 10
  Drive in additional stakes in the same manner, every 3 feet or so. Check to make sure that the tops of the stakes are level.
- 11
  Mix up a batch of concrete in a wheelbarrow or portable cement mixer.
- 12
  Pour the concrete into the trench. Use a board or trowel to smooth the surface of the footing so that it is level with the top of all of the wooden stakes.
- 13
  Let the footing dry before setting the brick or block wall in place.

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