Laying artificial grass directly on existing grass is not recommended for a long-lasting and aesthetically pleasing result. Proper preparation is crucial. Here’s a breakdown of the recommended process:
Why Not Directly on Grass?
Putting artificial grass directly on natural grass will lead to several problems:
- Poor Drainage: Natural grass retains moisture, which can lead to mold and mildew growth beneath the artificial turf, creating unpleasant odors and potential health hazards.
- Uneven Surface: Existing grass creates an uneven base, resulting in an artificial lawn that appears bumpy and unnatural.
- Weed Growth: Weeds can grow through the artificial grass.
- Compaction: The decaying grass underneath will compact over time, further distorting the surface.
The Correct Method: Preparing the Ground
Instead of laying the artificial grass directly on grass, the following steps are required to create a stable and long-lasting base:
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Remove Existing Grass and Topsoil: Use a turf cutter or spade to remove all existing grass and approximately 2-4 inches of topsoil. This creates space for the sub-base.
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Install Edging (Optional): Install edging around the perimeter of the area. This provides a neat finish and helps to contain the sub-base. Edging can be made from wood, plastic, or metal.
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Lay a Sub-Base: A well-compacted sub-base is essential for drainage and stability.
- Use crushed aggregate, such as MOT Type 1 (a mix of crushed stone and smaller particles), to a depth of 2-4 inches.
- Spread the aggregate evenly and compact it thoroughly using a plate compactor. This creates a firm and level surface.
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Leveling and Smoothing: Use a screed board or rake to create a perfectly level surface on top of the compacted sub-base.
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Weed Membrane: Lay a weed membrane over the entire area. This prevents weeds from growing through the artificial grass.
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Sand Layer (Optional): Some installers recommend a thin layer of sharp sand (approximately 1 inch) over the weed membrane. This helps to create an even smoother surface and allows for better drainage. Compact the sand lightly.
Installing the Artificial Grass
Once the sub-base is prepared, you can install the artificial grass:
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Unroll and Position: Unroll the artificial grass and position it over the prepared base. Allow it to settle for a few hours or overnight to acclimatize to the temperature.
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Cut and Shape: Use a sharp utility knife to trim the artificial grass to fit the area, leaving a slight overhang for final adjustments.
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Join Seams (If Necessary): If you need to join multiple pieces of artificial grass, use joining tape and adhesive specifically designed for artificial turf.
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Secure the Edges: Secure the edges of the artificial grass to the edging using galvanized nails or staples. Space them evenly to ensure a secure fit.
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Infill (Optional): Apply infill material, such as silica sand, to the artificial grass. This helps to keep the blades upright, provides cushioning, and adds weight for stability. Brush the infill into the fibers using a stiff brush or broom.
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Brush and Groom: Brush the artificial grass against the grain to help the fibers stand upright and create a natural look.
Summary
While it might seem tempting to lay artificial grass directly on existing grass, it's a shortcut that will lead to problems. Proper ground preparation involving removing the existing grass, installing a compacted sub-base, and using a weed membrane is vital for a long-lasting and beautiful artificial lawn.
