What is the best retaining wall base?

This is a difficult question to answer due to the nature of retaining walls and their function in different parts of the country and even the world. There are a few different styles of stone that could serve as a great base material for your wall. You need to consider what is going to be the best option with water management being a key factor in deciding which base to use. The two base materials that we enjoy using in Tennessee is Crush n Run and a 3/4 inch clean angular stone, also known as washed 57’s. 

The way water is managed around your retaining wall is going to be crucial in your base material decision. How do we want that water to exit our wall system? We can direct water to exit our wall through the face of our wall. We can guide the water to exit through the base of our wall. 

If we are building our retaining wall on a slope, this is the optimal time to guide all the water behind our wall to daylight through the base material. In this case we are going to place a washed 3/4 inch clean angular stone. We use this type of stone as our base for a retaining wall because it is an open grade aggregate that allows water to drain through it freely. 

If we are building our retaining wall on a fairly level ground, this is a great opportunity to utilize a dense grade aggregate like crush n run. when you build with this crushed stone, it will compact so tight the surface will become nearly impermeable. When you place your daylight drain in the face of the wall the water will be able to build up in your drain pipes and exit through the face of the wall. This prevents water from sitting in the base which could create a soft spots in you subsoil and induce excess settling in some areas of your wall. 

Understanding the damage that water can cause to your wall and how to manage the water is key. If your going to install your wall drain pipe in the base and daylight through a hillside washed 57’s is the way to go. If your on fairly level ground then crush n run is going to be your best option. Always keep water management in mind when choosing the best retaining wall base for your project.