How we worked it out
Updated as you change the numbers.
- Courses = height ÷ block height (+1 buried). Blocks per course = length ÷ block length.
- Base = length × 2 ft × 0.5 ft. Drainage stone = length × 1 ft × wall height.
Method and assumptions
Block manufacturers typically call for a compacted gravel base about 6 in deep and twice the block depth wide, with the first course buried, and clean drainage stone behind the wall with a perforated drain pipe at the bottom. Follow your block maker’s guide for setback and geogrid.
Questions
How many blocks for a 30 ft wall, 2.5 ft high, with 4 × 12 in blocks?
270 blocks: 9 courses (8 above ground plus 1 buried) of 30.
Sources
Method and figures checked on . Every worked answer on this page is covered by an automated test. Found a mistake? Tell us.