Artificial grass, commonly known as synthetic turf, is a surface material made from synthetic fibers designed to replicate the look of a natural lawn. While the term “waterproof” implies blocking water, artificial turf is actually highly permeable. It is specifically engineered to allow water to pass through it, which is the opposite of a waterproof barrier. This distinction is important because the effective management of water is a core design feature of any modern artificial turf system.
The Material: Permeability of Artificial Turf
The synthetic grass fibers themselves, typically made from polyethylene, polypropylene, or nylon, are non-absorbent and do not retain moisture. However, the turf’s ability to manage water is determined by the backing material that holds these fibers in place. Most landscape turf utilizes a backing made of polyurethane or latex, which is perforated with small, evenly spaced drainage holes.
These perforations allow water to pass rapidly through the turf and into the prepared ground below. Standard perforated backings are often designed to handle significant rainfall, with drainage rates that can exceed 30 inches of water per hour. Some advanced turf products feature a 100% permeable, non-perforated woven backing, which allows water to drain uniformly across the entire surface at even higher rates.
Ensuring Effective Drainage: Sub-Base and Installation
The permeability of the turf itself is only the first step; the entire drainage system relies on proper ground preparation and sub-base construction. Water that passes through the turf’s backing must continue to drain away effectively to prevent pooling and saturation. A professional installation requires the removal of existing topsoil, which is often dense and poorly draining, particularly if it contains a high percentage of clay.
The excavated area is then filled with a sub-base layer, typically 3 to 4 inches deep, composed of crushed aggregate materials like crushed stone, gravel, or decomposed granite. These materials are chosen because they compact tightly to provide a stable foundation but remain highly porous, allowing water to filter through rapidly. The aggregate base prevents the underlying native soil from shifting or expanding, which could lead to an uneven surface over time.
Another necessary step is grading the underlying soil and the sub-base material to create a slight slope, often a minimum of 1-2%. This gradient directs the water flow away from structures and towards designated runoff areas. Without this integrated system of permeable turf, porous sub-base, and proper grading, the water would become trapped between the turf and the ground, leading to issues.
Managing Moisture: Cleaning and Water-Related Issues
Water is not only managed by the turf system but is also a component of routine long-term maintenance. For instance, rinsing the surface with a hose is the primary method for cleaning debris and pet waste, requiring the drainage system to function correctly. Effective drainage is also the mechanism that prevents common water-related problems, such as the formation of mold, mildew, and unpleasant odors.
The infill material, usually silica sand or a specialized rubber blend spread between the synthetic fibers, plays an additional role in moisture management. Infill helps to keep the turf blades upright, which facilitates the flow of water down to the backing and sub-base. If infill is not maintained, it can become compacted over time, which reduces the turf’s overall drainage capacity and can lead to water buildup on the surface. Specialized infill materials with antimicrobial properties can further inhibit the growth of bacteria and mold that thrive in moist environments.