Retaining Walls Suffer From Moisture Problems
Whether you're driving down the road, or through a
neighborhood and you notice a retaining wall, that has large cracks in
it, or is severely discolored, or one that has white calcium deposits
from moisture, covering the entire wall, you've got problems with
The retaining wall is designed to hold the dirt back, that's its sole purpose. It's not going to hold any moisture back, unless someone has installed a waterproofing membrane to separate the soil from the concrete block wall. If the soil isn't ever going to get wet, then you probably don't need to waterproof the retaining wall.
However that's normally not going to be the case. So we need to waterproof the interior of our retaining walls to eliminate future moisture problems that could eventually, deteriorate as moisture starts to accumulate, inside of our block wall for a longer periods of time.
If you don't know anything about waterproofing, I would suggest that you hire a waterproofing expert. Waterproofing looks easier than it actually is, and might be out of your scope of work.
I'm not going to suggest that you use waterproofing paints, because I haven't seen great results with these products. However, if you're not that concerned about your retaining wall and are looking for a cheaper way to apply any waterproofing materials, these paints might not be a bad idea. Sometimes, Something is better than nothing.
If you live in a relatively dry climate, it might not be necessary to waterproof your retaining walls. But if you live in a damp or moist area, especially an area where the ground is moist all year round or more than six months out of the year, I would suggest that you waterproof the back of your retaining walls.