Excavate the area to the depth recommended by the engineer’s design section. Complete all over-excavation and re-compaction as required by the soils engineer.
Where permeability of the subgrade is important, excavation is in native strong soils, and site conditions permit, compaction of the subgrade may be limited to trimming. A qualified engineer should approve the subgrade before placement of base materials.
If required for site specific conditions and the engineer, install filter fabric over prepared subgrade.
If required, install any sub-drains / irrigation approved by local jurisdiction.
Install Base Materials
Backfill, level, and compact the required base materials (see Drivable Grass® master specification).
Install edge restraints if required. In some cases, these are installed before the base for structural support.
Install Bedding Layer
Install a minimum 2” thick bedding layer soil mix of 75% clean sharp sand and 25% fine ground compost for planted applications (see Drivable Grass® master specification and contact your local material supplier).
Moisture condition and lightly compact with a plate compactor or by screeding to get a uniform level surface to place the Drivable Grass® mats on.
For non-planted applications, the bedding layer is to be 1/2” nominal clean sharp sand (ASTM C33) for leveling.
Install the Drivable Grass® mats
Place the mats, working in one axial direction at a time, securely butting mats up against each other and leave no significant gaps. Trying to install Drivable Grass® in more than one axis at a time could result in a significant alignment problem. Make sure to check the alignment in both directions and make minor adjustments to ensure straight lines. It is recommended to install the Drivable Grass® mats in a “running bond” pattern.
The grid inside the Drivable Grass® mats can be cut with a utility knife or chisel to fit site conditions. At terminating edges or curved installations, the mats can also be cut with a masonry blade. Where possible, partial mats should be limited to edges where driving is limited. Also, no significant gaps should be left between the edge restraint and the mats.
Lightly compact the finished surface with a mechanical compactor, before the infill. To protect the concrete, cover the steel plate of your compactor with a fabric. This is absolutely necessary for non-planted proposed driving installations or installations that require light rubber wheel access before grass establishment.
For non-planted applications, staking of the Drivable Grass® is recommended. Please see typical staking detail. (http://soilretention.com/drivable-grass/professional/drawings/).
Infill and Seed
Fill the installed mats with the same soil mix as used for the bedding layer. Use a push broom to spread the soil mix evenly, recessing the mix at least ¼-inch below the mat surface. For best results the infill should not be saturated.
Broadcast seed over the installation area at the ratio prescribed by the seed provider / drawings. Sweep or lightly water excess seeds off the mat and into the soil mix.
Cover the seeded soil mix with a topper / seed cover to help retain moisture.
To lay sod, infill the soil mix about 1/4” above the mat surface, install the sod and roll to settle.
For non-planted applications, first sweep/infill the first 1/2″ of the mats with sand (ASTM C33) to fill in joints between mat edges. This can be achieved with a drop spreader and blower. Then add gravel infill to mats above sand infill.
If you are interested in artificial grass, see link below to our Drivable TurfTM video. (http://soilretention.com/media-coverage/)
Keep the soil evenly moist to promote germination. During germination, it is common to water for a short duration at intervals throughout the day. After germination, treat the new grass like a typical new turf lawn. Mow when it reaches 2-3 inches above the surface. Driving on Drivable Grass® can typically begin after the second mowing.
Tip: For areas that will receive limited or no traffic and a quick finished grass look is desired, consider laying sod over Drivable Grass®. Sod with a sand or well-draining backing is recommended.