Installation Instructions
43
RETAINING WALLS
Before calculating, keep in mind the following.
1. The base course should be a minimum of 24 inches wide and 6 inches deep.
2. Always core ll the Denver, Clifton and Corner Units.
3. In the Drainage Zone directly behind the blocks, install a 6 to 12 inch layer of aggregate. In
the calculations below we used a 12-inch drainage zone.
A. Base Course Formula
Length of the wall x the height of the wall x the width of back ll = cubic ft. divided by 27 = cubic
yards x 1.4 = tons of aggregate needed. For a base course 100 ft. long, 6 inches deep and 2 ft. wide
your calculations would be as follows:
100 x .5 x 2 = 100 cubic ft. / 27 = 3.7 cubic yards x 1.4 = 5.18 tons of aggregate in the base course.
The .5 equates to 6 inches of base. (6 / 12 = .5)
B. Core Fill Formula
Denver Blocks need 37 pounds of rock to ll their cores.
Beveled-faced with 500 sq. ft. wall we will need 715 units. (500 x 1.43 = 715 x 37 lbs = 26,455 /
2000 = 13.22 tons of core ll.)
Straight-faced with 500 sq. ft. wall we will need 665 units. (500 x 1.33 = 665 x 37 lbs = 24,605 /
2000 = 12.3 tons of core ll.)
Clifton Blocks need 50 pounds of rock to ll their cores.
Beveled-faced with 500 sq. ft. wall we will need 535 units. (500 x 1.07 = 535 x 50 lbs = 26,750 /
2000 = 13.38 tons of core ll.)
Straight-faced with 500 sq. ft. wall we will need 500 units. (500 x 1 = 500 x 50 lbs = 25,000 / 2000
= 12.5 tons of core ll.)
C. Drainage Zone Formula
For the drainage zone on a wall 100 feet long and 5 feet tall with one foot of topsoil above the
drainage zone your calculations would be as follows:
100 x 4 = 400 x 1 ft. of backll = 400 cubic ft. / 27 = 16.81 cubic yards x 1.4 = 20.74 tons of
aggregate behind the wall. Remember, we used 4 feet as the height because we are planning to
install 1 foot of soil above the drainage zone. It is common to install 8 to 12 inches of topsoil above
the drainage zone when planting softscape material.
D. Add the totals of A, B and C together = Total Aggregate for a 500 sq. ft. wall.
Denver Beveled Faced = 5.18 for base + 13.22 for core ll + 20.74 for drainage zone = 39.14 Tons
Denver Straight Faced = 5.18 for base + 12.30 for core ll + 20.74 for drainage zone = 38.22 Tons
Clifton Beveled Faced = 5.18 for base + 13.3 for core ll + 20.74 for drainage zone = 39.30 Tons
Clifton Straight Faced = 5.18 for base + 12.50 for core ll + 20.74 for drainage zone = 38.42 Tons
AGGREGATE ESTIMATES FOR THE BASE COURSE, CORE FILL AND DRAINAGE ZONE