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Wood Retaining Walls

A wood retaining wall often doesn't get noticed until it begins to topple.

Wood retaining walls are considered temporary, but their life expectancy can be improved by keeping the wood as dry as possible. To keep your retaining wall dry:

  • Dig a 6- to 12-inch-wide trench between the retaining wall and the hill it supports.

The trench should go to the bottom of the retaining wall.

  • Line the bottom and both sides of the trench with burlap cloth.
  • Place 6 inches of drain rock over the burlap in the bottom of the trench.
  • Install a 4-inch perforated drainpipe (perforations down) over the first layer of rock.

The drainpipe should daylight at some point beyond the end of the retaining wall. If possible, extend the pipe so that it drains directly into the public storm drain system.

  • Fill the rest of the trench with drain rock to within 6 inches of the top of the dirt being retained.
  • Cover the rock with a layer or two of burlap and cover that with 6 inches of soil.

Make sure that the support posts are not in unnecessary contact with any soil and that the surrounding earth is graded to shed water away from the posts and retaining boards.

Clean the wall and post annually with soap and water, and every year or so apply a fresh coat of oil-base wood preservative.