Artificial grass performs only as well as what lies beneath it. The infill, base preparation, and drainage system determine whether your turf will stay level and dry, resist odor, and last for years without settling or pooling. This guide walks through each layer of a proper installation: the infill materials available, how much you need, what base rock does, how drainage works, and the finishing details that separate a real installation from a quick lay-down on bare dirt. Whether you are installing residential artificial grass, a pet turf area, or a pool surround, the principles are the same.
Modesto's flat terrain, clay hardpan on the west side, sandy loam to the east, and hot dry summers create specific challenges. Water sits where it is not drained away, and heat can stress turf that has not been properly installed. Understanding these layers helps you ask the right questions and verify that any installer, including us, is building your yard to last.
Turf Infill Options: Silica, Coated Sand, Zeolite and Envirofill
Infill is the material that sits inside and on top of the turf fibres. It serves multiple purposes: it props the grass blades upright so they look natural and feel firm underfoot, it protects the backing from ultraviolet light, it adds weight to keep the turf from shifting, and it plays a role in drainage and odor control. The main infill families are silica sand, coated sand, zeolite, and specialty antimicrobial or cooling products.
Silica sand is the foundational choice. It is inexpensive, widely available, and effective at ballasting turf. Silica comes in different grades, from fine to coarse. Fine silica can compact over time and reduce drainage, so coarser grades are often preferred. Coated sand is silica that has been treated with a polymer or mineral coating. The coating makes the grains rounder and smoother, which is gentler on the turf fibres and on bare feet. Coated sand also resists compaction and can be coloured to match the turf or blend with the landscape. Zeolite is a porous mineral that absorbs moisture and odor-causing compounds. It is often blended with sand, particularly in pet turf installations, where odor control is essential. Zeolite does not eliminate odor on its own, but it reduces it and works best when combined with regular rinsing and cleaning. Antimicrobial and cooling coated infills, such as Envirofill and similar products sold under various names, are engineered to inhibit bacterial growth and reduce surface temperature. These are more expensive than standard infills but can be valuable in high-traffic pet areas or in yards where heat is a concern. Crumb rubber, made from recycled tires, is a sports-field infill used on athletic courts and synthetic turf fields where impact absorption is critical; it is not typically used in residential yards.
How Much Infill Artificial Grass Needs, and Why
Infill quantity is specified in pounds per square foot, and it varies depending on the turf product, pile height, and intended use. A typical residential installation uses between 1.5 and 3 pounds per square foot of infill, with pet areas and high-traffic zones often at the higher end. The infill amount matters because too little leaves the fibres standing loosely, makes the turf feel thin and unstable underfoot, and exposes the backing to UV damage. Too much infill can oversaturate the turf and slow drainage. The right amount is a balance, and it should be specified in writing before installation begins.
Cheap installations often cut corners by using less infill than the product requires. This saves money upfront but results in turf that looks flat, feels thin, settles unevenly, and ages faster. When you request a free estimate, ask the installer to specify the infill type and the exact pounds per square foot they will install. This figure should appear in your written specification, not as a promise but as the measured standard for your yard and your product. If an installer cannot or will not name the infill amount in advance, that is a red flag.
What to Put Under Artificial Grass for Drainage
The foundation of artificial grass begins before the turf is laid. The first step is removal: existing lawn, old turf, roots, and debris must be cleared away. Once the area is bare, the ground is excavated to the depth needed for base preparation, typically three to four inches. This excavation also allows you to regrade the yard so water flows away from the house and away from any pool or patio. After excavation, a weed barrier fabric is often laid down. This barrier prevents weeds from growing up through the turf, though it is not always necessary in every situation; your installer will advise based on your soil and yard history.
Next comes the base material, usually decomposed granite or crushed base rock. This material is spread in layers and compacted firmly with a plate compactor so it becomes a stable, level surface. The compacted base prevents settling, which would create dips and soft spots in the turf. Once the base is solid, an optional draining underlay or pad may be installed. For patios, balconies, and hard surfaces, an underlay is essential to allow water to drain away from the slab and prevent pooling. For pet areas, an underlay adds comfort and improves drainage, which is critical for odor control. On concrete or existing paving, turf should never be glued flat to the surface; water will trap underneath and cause odor, mold, and backing failure. Finally, the turf is unrolled, seamed, and secured.
Base Prep on Modesto Soil: Excavation, Base Rock and Compaction
Modesto's soil varies by location. The east side tends toward sandy loam, which drains reasonably well, while the west side and areas closer to the valley floor often sit on clay hardpan, which sheds water rather than absorbing it. Hardpan is dense, compacted clay that has formed over time and blocks drainage. When artificial grass is installed over poor-draining soil without proper base preparation, water pools under the turf, causing odor, soft spots, and premature backing failure. This is the most common failure in yards with clay soil.
Base preparation begins with excavation to remove the top layer of poor soil and create a level grade. The excavated area is then filled with decomposed granite or crushed base rock, a free-draining material that allows water to move through it. This base material is spread in lifts (typically two-inch layers) and compacted firmly with a plate compactor. Each lift is compacted before the next is added, so the finished base is stable and will not settle under foot traffic or weight. The base is graded with a gentle slope away from the house, the pool, and any low areas where water might collect. A properly compacted three- to four-inch base is standard for residential installations. Without compaction, even the best turf will develop dips, divots, and areas where infill settles, creating uneven wear and exposed seams. If your yard has a genuine water problem, such as a high water table, poor site drainage, or a history of standing water, that issue must be addressed before turf is installed. In those cases, a more extensive drainage solution may be needed, or the turf installation may be declined until drainage is resolved.
Artificial Grass Drainage and Underlay: Perforated vs Fully Permeable
Artificial grass itself is permeable, but the rate at which water passes through varies by product. Drainage is measured in gallons per hour per square foot (GPH/SF). Turf with a perforated backing allows water to drain through the holes in the backing layer, while fully permeable backing allows water to flow through the material itself. Both can work well, but the actual drainage rate depends on the backing design and the infill you use. A high-drainage-rate turf (4 to 6 GPH/SF or higher) is essential in areas that receive heavy water exposure, such as pet areas, playgrounds, and areas around pools where splashing and rinsing are frequent.
However, even fast-draining turf will fail on a base that does not drain. If the base is compacted clay or uncompacted soil, water pools underneath regardless of the turf's drainage rate. This is why base preparation and site grading are as critical as the turf itself. For hard surfaces such as patios and balconies, an underlay or drainage pad is installed between the turf and the concrete or paving. The underlay allows water to flow to the edges and drain away, preventing pooling and odor. On sloped surfaces, edge drainage should be installed to direct water away from the slab. When you review a turf spec, ask for the drainage rate in writing and confirm that the base will be properly excavated and compacted. If the installer cannot explain how water will drain from your specific yard, that is a reason to ask more questions.
Seams, Nails, Edging and Power Brooming
The finishing details of an installation reveal whether the work was done carefully or rushed. Seams are joined using seam tape and a flexible adhesive designed for synthetic turf. A proper seam is aligned so the grain of the turf on both sides runs in the same direction, creating an invisible or nearly invisible line. Seams that are visible, wrinkled, or peeling indicate poor technique or inadequate adhesive. The turf is secured to the ground using nails or staples spaced at the correct intervals (typically 6 to 12 inches apart, depending on the product and conditions). Nails should be driven flush so they do not catch feet or mowers, and they should be placed where they will be covered by infill or hidden by edging.
Edges are finished with bender board, metal edging, or a similar perimeter material that holds the turf in place and creates a clean line between the turf and the surrounding landscape or hardscape. Turf cut tight to pavers, pool decks, or patios prevents water from pooling at the edge and keeps the installation looking finished. After the turf is secured and the seams are set, the entire area is power broomed. Power brooming stands the turf fibres upright and spreads the infill evenly across the surface. Without power brooming, the turf looks flat and matted, and infill distribution is uneven. A visible seam, lifted edges, loose nails, or uneven infill are signs that the installation was not finished properly. When you inspect a completed installation, walk the entire perimeter, press on seams, and run your hand across the surface to feel whether the fibres are standing up and the infill is evenly distributed.
What a Written Turf Spec Should Include
Before any work begins, every installation should be backed by a written specification that names the exact materials and methods that will be used. This spec is your guarantee and your reference if questions arise later. The spec should include the turf product name and fibre type, the face weight in ounces per square yard, the pile height in millimeters, the backing type and drainage rate in gallons per hour per square foot, the infill type and the pounds per square foot that will be installed, the base material and depth (typically 3 to 4 inches), the base compaction method, whether a weed barrier will be used, the seam method and adhesive type, the edging material and method, cleanup and haul-off of old material, and the workmanship warranty period. A one- to three-year workmanship warranty on the installation is standard; this covers the quality of the work, not the turf product itself.
A written spec protects both you and the installer. It prevents misunderstandings about what will be installed, ensures that shortcuts are not taken, and gives you a clear reference if any issue arises after installation. When you request a free estimate, ask for a detailed spec in writing before you commit. If an installer is unwilling to name the product, face weight, infill amount, base depth, and compaction method in advance, you have no assurance of the quality of the work. Visit the pricing page to understand how estimates are measured and what to expect, and call us at (209) 882-9634 if you have questions about what a proper spec includes.