What is the difference between ledge rock and grindstone?

• Both ledge rock and grindstone are types of sedimentary rock, but ledge rock is far more dense than grindstone.  Grindstone was a very popular choice for natural looking retaining walls about 10 years ago.  Unfortunately it was discovered that grindstone did not weather our Michigan winters very well.  It is too soft and deteriorates too quickly, so we do not recommend the use of grindstone to our customers.  Ledge rock is a very popular and durable alternative.

What is an engineered modular concrete wall?

• When the purpose of a modular concrete retaining wall is to support a heavy load [a parking lot or driveway on top of the wall] or when the wall needs to be exceptionally high, it must be engineered.  Engineering assures that such walls will remain structurally sound attractive for years to come.
• Unilock, our preferred supplier of modular concrete products, has structural engineers on staff to provide our staff with necessary plans for any engineered walls we build. 
  • They evaluate:
    • Your soil type
    • Your soil's level of compaction
    • The load your wall must bear
  • They then specify the type of backfill the wall requires and the location of any Geo-grid that should be utilized.  [Geo-grid is a special plastic mesh product that provides critical lateral support for certain retaining walls.