This is part 1 of a 3 part series that will describe in detail how to install artificial grass. This first part discusses sub-base preparation and the steps involved in securing a proper sub base. These first steps include excavation and choosing, among other things, a sub base material, weed barrier, perimeter board and base compaction. And be sure to check back to see parts 2 and 3 in the next week or so.
And for a comprehensive guide on how to install artificial grass on your own, download the DIY Easy Install Guide.
A good sub-base is the foundation for a lasting, beautiful install. Starting with excavation, a good rule of thumb is that you should excavate down to three inches below finished grade which varies based on your particular application and the type of native soil.
Soils that are sandy, silty or contain a lot of clay will require additional excavation (perhaps four to six inches below finished grade.) Firm soils, or soils that are rocky or similar in composition to decomposed granite, you may be able to get by with a little less (perhaps two inches.)
That being said, we always recommend a minimum of at least three inches to ensure a solid sub-base foundation. We also recommend the use of a geo-textile fabric between your native soil and our sub-base to prevent base contamination if you have soils with a high concentration of clay.
The Bend-A-Board to be used here is distinct from a landscaping Bend-A-Board or a Wonder Edge product that are used mostly for aesthetic purposes. The sub-grade Bend-A-Board in artificial grass serves a structural purpose – as a nail board along the perimeter of your project to provide a more robust installation.
The use of a sub-grade, composite Bend-A-Board enables you to secure the artificial grass using a pneumatic staple gun rather than putting nails through the artificial turf into your sub-base. The Bend-A-Board is secured in place with 12-inch composite redwood stakes set approximately every three feet.
The composite stakes are screwed into the Bend-A-Board. This holds the Bend-A-Board in place and at the proper elevation. The top of your Bend-A-Board should be even with the top of your sub-base.
When installing the Bend-A-Board, leave a half inch gap between the Bend-A-Board and any constructed restraints (sidewalks, patios, walkways, etc.).
In addition, we recommend that the top of your Bend-A-Board and the top of your sub-base should be about a half-inch below any adjacent sidewalks, patios, and walkways. You want to maximize the amount of pile height that is above adjacent flat work for the most realistic appearance.
Adding the Bend-A-Board step in the installation process usually adds about $0.30 per square foot to the total job cost.
Spread and Compact Base
Your base is usually one of the following:
- class II road base
- crushed, miscellaneous base
- cement-treated base
- decomposed granite
Road base compacts better and is less expensive than decomposed granite, but it’s harder to obtain a really smooth surface and doesn’t drain as well.
Decomposed granite, on the other hand, drains better and provides for a very smooth surface, but is more expensive.
As a general rule, road base is used for landscaping applications and decomposed granite is used for putting greens. Oftentimes though on putting greens people opt to do the bottom two inches in road base and the top one inch in decomposed granite for cost considerations.
This is a critical step in the installation process. The primary reason you removed three inches of native soil and replaced it with base material was to replace an expansive sub-base (soil) with one that will not expand.
If you install artificial grass over an expansive soil, over the course of time (and weather variations) the soil will expand and contract. As it expands it will pull or push on the artificial grass, and as it contracts you will be left with bubbles and buckling in the surface of your grass that will make it look like carpet that needs to be stretched out.
This is why it’s vital to get a good compaction on your sub-base. This is typically done with a vibratory-plate compactor, roller, and a hand tamper to get those hard-to-reach areas and tight corners. Be sure to wet down your base as you’re compacting it to help remove any voids or air spaces.
We recommend that you incorporate minor grade changes to provide the most realistic look. Crowning the middle is always an excellent option. Also, be sure that you are accounting for water runoff. Like most flat work installations, you want a one to two percent fall and give consideration to where and when drain lines are necessary or appropriate.
Installation of a Commercial-grade Weed Barrier
It’s unlikely that you’ll get weeds coming up through your artificial grass, but that doesn’t mean it never happens. If you didn’t do enough excavation, or your sub-base is contaminated, you may get weeds that grow through drainage holes. For these reasons, a weed barrier can be used as an added layer of protection.
This concludes part one of the artificial grass installation tips series. Look out for parts two and three to be published here to the Purchase Green blog over the next two weeks. And for a comprehensive guide on how to install artificial grass on your own, download the DIY Easy Install Guide.