Lowe's Home Improvement

Planning for a Block Retaining Wall

Install Retaining Walls

Retaining walls are a great do-it-yourself project to prevent soil erosion, stabilize slopes or create a beautiful terraced landscape. With just a few simple steps, calculate how many blocks you'll need to build a retaining wall.

Calculating Your Project

1. Estimate the number of courses of block in your finished wall. For walls under 24 inches high, bury half of the first course. For walls over 24 inches high, bury the first full course.

Number of block layers = Desired wall height ÷ Block height

2. Determine the number of blocks needed by multiplying the total number of blocks per course times the number of courses.

Length of wall in inches _____ x Height of wall in inches _____ = Total square inches _____ Total square inches ÷ 144 = ______

3. Determine the total cubic feet of paver base needed by multiplying the number of linear feet of wall by .2 cubic foot.
This will give you a 2-inch-deep base, 16 inches wide. Please refer to specific product information for the recommended base depth.

Total linear feet of wall ____ x .2 Cubic foot = _____ Total cubic feet of drainage

Example: 10 Linear feet of wall x .2 Cubic foot = 2 Cubic feet of paver base needed (1 Cubic foot = 120 Pounds)

4. Calculate the amount of drainage aggregate that you’ll need behind the wall.

Total number of blocks ____ x .2 Cubic foot = _____ Total cubic feet of drainage aggregate needed

This will give you 6 inches of drainage aggregate behind the wall. 
Example: 35 Total blocks x .2 Cubic foot = 7 Cubic feet of drainage aggregate needed behind the wall (1 Cubic foot = 120 Pounds)