Most Allan Block retaining wall units have an average depth (front to back) of at least 10 in. (25 cm). The 10 in. (25 cm) minimum depth of facing unit is recommended because segmental retaining wall units of this depth or greater have a proven performance record while in service over many decades. This recommendation also recognizes that as the unit depth decreases, so does the stability of the facing, particularly overturning resistance during construction or while in service.
Smaller srw's, including smaller Allan Block products have a depth of less than 10 in. (25 cm). These blocks should be limited to walls not exceeding 10 ft (3 m) in total height, unless used in conjunction with larger blocks in a patterned wall. (ref. BP, Chapter 2.12)
Allan Block is working to achieve our industry initiative of Zero Wall Failures. With our Best Practices Manual and experience in the industry we are trying to expand the knowledge base for the design of segmental retaining walls (SRW's) by communicating and educating the professionals in the industry. To see the full Best Practices Manual, visit allanblock.com to download today and keep an eye out for more industry Best Practice recommendations here.