These retaining walls are falling down in Oakland Township, Michigan. Even the short walls are leaning and seperating.
Why?
1) The blocks used to construct these walls are not retaining wall blocks. They are planter retention wall blocks and can only be used in walls up to 16″ high and that is only under optimal conditions . These walls are 48″ high. The builder should have used something like Unilock’s Pisa II block, or Anchor Wall (Versalock).
2) All the blocks of these walls do not have glue to hold them together and some blocks had only a dab of glue.
3) Improper drainage behind the walls.
4) I suspect an improper base was used due to the shorter walls leaning and seperating. Proper base for walls of these height is 8″ – 12″ deep of compacted gravel and the base should be wider than the wall. A 12″ wall should have a minimum 18″ wide base.
These walls were only 7 to 8 years old. Properly built walls, using appropriate materials, should stand straight and tall for twenty years without any issues for the homeowner. We do not recommend attempting to repair these walls.
It is vital that when you shop for a landscape contractor, you do not only choose your contractor based upon price. There are a lot of guys with a truck and a shovel, make sure they can build your landscape project to stand the test of time.
