Sub-base. What is it? Who needs it? Well, if you’re installing artificial grass, you do, my friend.
Sub-base goes where your natural grass was once you’ve excavated down a few inches and before you install the grass. Its primary job is to prevent the natural expansion and contraction of your yard’s native soil from affecting the turf, thus preventing wrinkles from popping up.
In most professional installations, it’s one of three things:
- crushed miscellaneous base – CMB,
- class II road base, or
- decomposed granite.
Decomposed granite is considered the best of the three due to its superior drainage and ability to render a consistently flat surface. Certain types of installations, like putting greens, need decomposed granite sub-base more in order to perform and last. The problem with decomposed granite is it’s expensive.
Is there a workaround?
In most cases, you can get good performance and longevity out of artificial grass with the use of only a small amount of decomposed granite. In fact, only the top few inches of sub-base need to be decomposed granite in order to get good drainage and overall performance. This means you can fill most of your excavated area with inexpensive class II or CMB, then just spread a few inches of decomposed granite on the surface. This will bring down the cost considerably and produce fair results.
That being said, there are some installations for which we never recommend skimping on decomposed granite subbase. If you receive lots of rainfall, or already have drainage issues in your yard, this strategy isn’t likely to work out. Be sure to discuss your project’s particulars with our turf experts for more guidance.
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