Can I Put a Grass Driveway System in on Grass Already There?

Subgrade for Hard Surfaces

• Soil movement creates settling and subsequent cracking and shifting of concrete or pavers. For paved surfaces, it's important to have well-drained, compacted gravel for the base. Grass pavers, also called turf stone, are installed to reduce impervious surfaces with a system of concrete blocks to provide a strong structural surface for the driveway, with grass seed planted in the voids. Site preparation for grass pavers is essentially the same as for other paved material for driveways.

Topsoil Properties

• Grass requires the opposite qualities in a sub-base as hard surfaces do. Plants need oxygen and water to thrive; topsoil is composed of particles of different sizes and pore spaces that permit water and oxygen to enter. The moisture-holding capacity of topsoil is valuable for storing water for plant growth. Compaction is detrimental to growth; it compresses soil particles close together so that water and oxygen can't circulate. Aeration is conducted regularly to amend compaction in lawns.

Grass Pavers Subgrade

• Grass is seeded on a base of topsoil. Made up primarily of organic matter, the soil contains moisture and lacks the uniformity that hard surfaces require. It also settles at different rates. The subgrade for grass pavers is prepared by removing organic matter and soft soils and replacing it with 6 inches of crushed gravel; the gravel is compacted. Bedding sand is applied on top of the gravel to a depth of 1 to 1 1/2 inches.

Grass Pavers

• Grass pavers are set on the bedding sand and compacted to lock them into place. Topsoil and grass seed is spread across the voids and the surface compacted again. The voids in the pavers are 3 1/2 inches deep, which is adequate for cultivating grass seed. They retain moisture and warmth, creating a hospitable environment for the grass. The compacted subgrade material maintains the structural stability of the paving.