Artificial grass installed on a poor base or inadequate drainage will fail within a few years, no matter how good the turf itself is. This guide walks you through the hidden half of a turf installation: what goes underneath, how water moves through it, how to specify it in writing, and what separates a careful installer from one cutting corners. Whether you are converting a bare patch in your Chattanooga yard, preparing a dog run that stays dry and odor-free, or installing turf around a pool deck or patio, the base and drainage system determine whether your investment lasts.
Chattanooga's sticky red clay, afternoon thunderstorms, and shaded backyards create real drainage challenges. This guide explains the options, the local soil conditions you will encounter, and the questions to ask any turf installer, including how much infill your turf needs, what materials go under it, and what a professional specification should include in writing.
Turf Infill Options: Silica, Coated Sand, Zeolite and Envirofill
Infill is the granular material spread into the turf after installation. It serves multiple purposes: it props the synthetic fibres upright so they feel and perform like real grass, it protects the backing from UV damage, it adds weight to keep the turf in place, and it plays a role in how quickly water drains through the system. The type and amount of infill you choose depends on the application, the local climate, and whether pets will use the area.
Silica sand is the most common and least expensive infill. It is a natural mineral ballast that does its job well in most residential settings. Coated sand consists of silica grains rounded and coated with a thin layer of material, often colored. Coated sand is gentler on the turf fibre, may reduce dust in dry conditions, and feels slightly softer underfoot than sharp silica. Zeolite is a porous mineral that absorbs and neutralizes ammonia and other odors, making it a popular choice for pet turf and dog runs. It costs more than silica but can be worth it if odor control is a priority. Antimicrobial and cooling coated infills, such as products sold under the name Envirofill, are engineered to reduce bacterial growth, lower surface temperature in intense sun, and manage odor. These are premium options that cost more but may extend the life of the turf and improve comfort in Chattanooga's hot, humid summers.
Crumb rubber (recycled tire material) is used primarily on sports fields and playgrounds where impact absorption and drainage under heavy use are critical. It is not typically recommended for residential yards or pet areas, and many HOAs restrict or prohibit it. Always check your HOA rules before selecting any infill type.
How Much Infill Artificial Grass Needs, and Why
Infill quantity is specified in pounds per square foot, and it is one of the most commonly overlooked details in a cheap installation. Too little infill is a quick way to cut costs and cut corners. When infill is sparse, the turf fibres do not stand upright properly, the backing is exposed to UV and degrades faster, and the turf feels thin and lifeless underfoot. In rainy climates like Chattanooga, inadequate infill also means water does not distribute evenly, leading to muddy spots and odor problems in pet areas.
Typical residential turf requires between 1.5 and 2.5 pounds of infill per square foot, depending on the pile height, fibre type, and backing. Pet turf and play areas often call for slightly more. A professional installer will specify the exact amount in writing before work begins, and you should ask for this figure and hold them to it. If an estimate does not name the infill weight, ask why. The difference between a properly filled installation and an under-filled one shows within a season, especially in a yard that gets heavy use or heavy rain.
What to Put Under Artificial Grass for Drainage
The sequence of layers under artificial grass matters as much as the turf itself. Start by removing the existing lawn, old turf, and roots down to bare soil. If there is old turf that is lifting, melting, or failing, it must come out completely; laying new turf over bad turf is a recipe for future problems. Once the area is cleared, excavate to the depth required by your base specification, usually three to four inches for residential yards in Chattanooga.
Next, install a weed barrier if appropriate for your site. In areas where weeds are a concern and drainage allows, a permeable landscape fabric prevents roots from growing up through the base and into the turf. On sites with severe drainage problems or heavy clay, a weed barrier may not be necessary and can sometimes trap water, so discuss this with your installer. After the weed barrier (if used), lay and compact a free-draining base of decomposed granite or crushed base rock. This material is compacted in thin lifts, typically two to three inches at a time, using a plate compactor or similar equipment. Proper compaction is essential; loose base material will settle unevenly, causing dips and puddles.
For patios, balconies, pool decks, and other hard surfaces, or for pet areas where extra cushioning and drainage are desired, an optional draining underlay or pad goes down next. These products are permeable, add comfort, and help water move away from the surface. Finally, the turf is laid over the prepared base. On concrete or sealed surfaces where water cannot drain into the ground, a draining underlay is not optional; it is essential. Never glue turf flat to a concrete slab without a draining layer underneath, as water will pool and the turf will fail.
Base Prep on Chattanooga Soil: Excavation, Base Rock and Compaction
Chattanooga sits on sticky red clay over limestone and chert, and this soil drains poorly, especially after the afternoon thunderstorms that bring heavy rain in summer and fall. A base that is not properly prepared will settle unevenly, trap water, and create muddy spots and odor problems within months. The goal of base prep is to create a firm, level, well-draining platform that sheds water away from the house and pool and into the ground or drainage system.
Excavation begins by removing the existing lawn and roots, then digging to the depth specified in your turf plan, typically three to four inches. Once excavated, the base area should be graded with a slight fall away from the house, pool, deck, or any structure that could be damaged by standing water. This slope does not have to be steep; a gentle grade is enough. The base is then filled with decomposed granite or crushed base rock, which is a coarse, angular mineral aggregate that compacts firmly and allows water to percolate. This material is compacted in lifts using a plate compactor or walk-behind compactor, typically two to three inches at a time. Each lift is compacted firmly before the next is added. Proper compaction prevents settling, which causes dips and puddles where water collects and odor builds up.
If your yard has a history of water pooling, soggy ground after rain, or surface runoff that does not drain away, the base prep alone may not solve the problem. In cases where drainage is severely compromised, a subsurface drain line, grading work, or other site-specific solutions may be necessary before turf installation makes sense. If drainage cannot be addressed, the installation should be declined rather than attempted on a failing base.
Artificial Grass Drainage and Underlay: Perforated vs Fully Permeable
Artificial grass itself is permeable; water passes through the turf fibre and the backing into the base below. However, the rate at which water drains is critical, and it is measured in gallons per hour per square foot. A typical residential turf backing allows 20 to 40 gallons per hour per square foot to pass through. This sounds like a lot, but in Chattanooga's heavy afternoon thunderstorms, with several inches of rain falling in an hour, the turf and base together have to move that water quickly or it backs up and pools.
Perforated backing has small holes punched through it, which speeds drainage. Fully permeable backing allows water to pass through the entire material. Both are effective, but the difference is most noticeable in heavy downpours and in pet areas where urine concentration is high. In a pet run or a yard with poor base drainage, a fully permeable backing and a well-compacted base are worth the extra cost. Always ask your installer to name the drainage rate of the turf backing in writing. If they cannot or will not, that is a red flag.
Underlays and pads designed for drainage are used under turf on hard surfaces like concrete, patios, and balconies. These products are permeable and allow water to flow away from the surface rather than pooling under the turf. On a solid surface, an underlay is not optional; it is the only way to prevent water from being trapped. Even with a fast-draining turf and a draining underlay, however, a poorly compacted or impermeable base will cause failure. Drainage is a system; no single layer does the job alone.
Seams, Nails, Edging and Power Brooming
The finishing details of a turf installation reveal whether the work was done carefully or rushed. Seams are where two pieces of turf meet, and they are the most visible weak point of any installation. A professional seam is joined with a seam tape and a flexible polyurethane adhesive applied to the tape and the backing of both pieces. The grain of the turf (the direction the fibres are combed) must be aligned so the seam is not visible or is minimized. A visible seam, a gap between pieces, or a seam that lifts or separates within the first year indicates the work was not done to standard.
Nails or staples secure the turf perimeter and hold seams in place while the adhesive cures. They should be spaced every 6 to 8 inches around the edge and at seams, driven flush with the backing so they do not catch feet or equipment. Edging is the perimeter finish. Bender board (flexible wood edging) or metal edging secures the turf edge, prevents unraveling, and creates a clean line. Edges should be tight against pavers, decks, and hardscape, with no gaps or loose material. Around a pool or on a cool deck, turf is cut to fit snugly against the edge so there is no trip hazard or place for water to pool.
Power brooming is the final step. After infill is spread, the turf is brushed with a power broom or similar equipment to stand the fibres upright and distribute the infill evenly. This step makes the turf look and feel full, hides seams, and ensures infill is not clumped in one area. A turf that looks flat or matted, or where seams are obviously visible and raised, was either not power broomed or was broomed too lightly.
What a Written Turf Spec Should Include
Before any work begins, ask your turf installer for a written specification that includes every detail of the job. This document protects you and holds the installer accountable. A complete spec should name the turf product and fibre type (for example, polyethylene or nylon), the face weight (ounces per square yard), the pile height (length of the fibre), the backing type and drainage rate (gallons per hour per square foot), the infill type and pounds per square foot, the base depth, base material, and compaction method, whether a weed barrier will be used, the seam method and location, the edging type and perimeter details, and cleanup and haul-off. The spec should also state the workmanship warranty period, which covers the installation labor and seams, typically one to three years.
A written spec is your proof of what was promised. If the installer balks at providing one, or if they provide an estimate with vague language like "quality turf" and "standard base" without naming the product, face weight, infill, or base depth, you do not have enough information to judge the quality or to enforce it later. Chattanooga Turf Installation provides a written turf spec for every job. If you are getting estimates from multiple installers, use the spec as your comparison tool. Ask each one to fill in the same details so you can see exactly what you are paying for. For a free estimate and a written spec tailored to your yard, contact us for an on-site measurement, or visit our pricing page to understand the range of options available.