Should You Put Weed Barrier Down Before or After Installing a Base Layer?

First, let’s go over why you need a base layer. The base layer creates a level platform and provides drainage for artificial turf. When installing a synthetic grass base layer, excavate 3 to 4 inches of topsoil. The best materials for the base layer are 3 inches of class II road base followed by an inch of decomposed granite (also known as granite dust). 

You can lay weed barrier fabric under the base layer, over the base layer, or both.

Lay the landscaping fabric under the base layer to prevent contamination and provide a ground stabilization membrane.

If the native soil is hard (as opposed to clay-like), there is no need to install weed barrier fabric under the base material. Simply lay the weed suppressant membrane over the base.