April 20, 2018

Does soil type matter when building a retaining wall and how do I tell what kind I have?

Written by: Danelle DeMartini
A retaining wall – no matter what type of material you plan to use, is designed with one main function in mind; to hold back the dirt.  Knowing exactly what kind of dirt you have makes ALL the difference in how you build that wall.  To figure out what type of dirt you are dealing with, try digging a handful of soil about a foot below the surface and form it into a ball. There are basically 3 types of soil to be able to identify when planning to construct a retaining wall:
·        Clay
·        Sandy
·        Organic

Clay type soils hold a lot of moisture, which adds additional weight to the soil, making the retaining wall’s job more difficult. You can identify a clay type soil popular type of soil and when in doubt – assume your dirt is a clay based soil.

Sandy type soils allow for water to pass through easily and are idea for building walls as they don’t add any extra weight to the soil. You can identify a sandy type soil if the dirt holds is grainy without fine particles, and falls apart when you try to make a ball.

Organic type soils like black dirt or top soil, stick together but will not hold together once you let go and should NEVER be used to build a wall.

Now that you know what type of dirt you have, designing your retaining wall for the right soil type will ensure your wall will withstand the test of time.  For more information on building a retaining wall, visit allanblock.com