The foundation determines the superstructure. Gain a deeper understanding of the selection of crushed stone, granite, and other base materials.
A stunning, long-lasting artificial turf installation starts with one non-negotiable element: a stable foundation built from the right sub-base materials. Even the highest-quality synthetic grass will fail to perform—developing bumps, drainage issues, or shifting over time—if laid on a poorly prepared base. The question what is the best base for artificial turf is one of the most critical for DIY enthusiasts and professional installers alike, as the base layer dictates the turf’s drainage, flatness, and overall durability for decades to come.
Turflory, a leading manufacturer of premium artificial turf for residential, commercial, and pet-specific use, has engineered its products to pair perfectly with science-backed base construction. In this guide, we’ll break down why grassroots preparation is make-or-break, the best sub-base materials for every application (including pet turf and high-traffic landscapes), common materials to avoid, standard thickness guidelines, and Turflory’s step-by-step grassroots construction process. Whether you’re installing a backyard lawn, a pet play area, or a commercial landscape, this guide will ensure your ground preparation is done right the first time.
Why is grassroots so important? (Drainage and flatness)
The grassroots layer of an artificial turf installation serves two core, irreplaceable functions: unimpeded drainage and perfect, long-term flatness—and both are essential for a turf that looks great and performs even better for years.
A well-constructed base acts as the primary drainage layer for your artificial turf, channeling rainwater, pet urine, and melting snow away from the turf’s backing and into the soil below. Poor drainage leads to standing water, which weakens the turf’s adhesive, breeds mold and mildew, and creates a slippery, unsafe surface—especially critical for pet-friendly spaces where quick drainage is non-negotiable. Turflory’s pet turf collection is designed with advanced drainage backing, and this performance is only maximized when paired with a properly built drainage base.
Flatness, on the other hand, ensures the turf lies smooth and seamless, with no bumps, dips, or uneven areas that cause wrinkling or premature wear. A flat base eliminates tripping hazards, keeps the turf’s fibers upright for a natural look, and ensures infill is distributed evenly. Over time, a poorly compacted or uneven base will settle, creating unsightly and unsafe dips—this is why professional ground preparation is not a step to skip.
Beyond drainage and flatness, a strong grassroots layer also prevents weed growth from below the turf, adds structural stability to resist shifting from foot traffic or wind, and provides a firm, supportive surface for the turf to adhere to. Simply put: the quality of your grassroots directly determines the lifespan of your artificial turf installation. For more landscape-specific base guidance, explore Turflory’s comprehensive landscape turf resources.
Best material recommendation: CMB and crushed granite
When it comes to answering what is the best base for artificial turf, two materials stand head and shoulders above the rest for residential, commercial, and pet applications: CMB (Crushed Miscellaneous Base) and crushed granite (including decomposed granite, or DG). These materials are the gold standard for artificial turf sub-bases because they compact tightly to form a hard, stable surface, feature angular particles that lock together (preventing shifting), and create a porous structure that enables exceptional drainage—solving the two core challenges of grassroots construction in one.
CMB, a blend of crushed stone, gravel, and fine stone dust, is the top choice for high-traffic areas, commercial landscapes, and pet play areas. Its dense, compacted structure offers unbeatable stability and drainage, making it ideal for spaces that see heavy use or require quick water runoff. Crushed granite, by contrast, is a lighter, more versatile option—perfect for residential lawns, patios, and low-traffic areas. Decomposed granite (DG), a fine, crushed form of granite, is a subset of this material that creates an ultra-smooth base surface, ideal for turf that demands a flawless, natural appearance.
Both CMB and crushed granite are superior to other base materials because they do not compact into a solid, non-porous layer—instead, their angular particles leave tiny voids that act as a natural drainage layer, while still locking together to form a firm, flat surface. This balance of stability and drainage is what makes them the go-to road base and turf base materials for professional installers worldwide, and Turflory exclusively recommends these materials for all its artificial turf products.
The success of CMB and crushed granite as sub-base materials hinges on correct particle size—too large, and the base will never compact flat; too fine, and it will lose its drainage capabilities and turn muddy when wet. Turflory’s professional installation team recommends a blended particle size for both CMB and crushed granite, with a mix of coarse, medium, and fine particles to create the perfect balance of compaction, stability, and drainage.
For the primary sub-base layer (the thickest layer of your grassroots), use a 1–2 inch (2.5–5cm) particle size of CMB or crushed granite—this coarse mix forms the structural foundation and main drainage layer. For the top base layer (a thin finishing layer), use decomposed granite or fine crushed granite with a particle size of ¼ inch (0.6cm) or less—this fine layer smooths out the coarse sub-base, creating a perfectly flat surface for laying the turf and preventing sharp stones from damaging the turf’s backing.
Avoid single-size particles at all costs: a base made of only large stones will never compact flat, while a base of only fine dust will become waterlogged and unstable. The blended particle size is the key to a base that is both rock-solid and highly drainable.
Avoid using materials such as topsoil or round stones
While CMB and crushed granite are the ideal sub-base materials, there are several common materials that should never be used for artificial turf grassroots construction—they fail to meet the core requirements of stability, compaction, and drainage, and will lead to a failed installation in the short or long term. The two most problematic offenders are topsoil and round stones (river rock, pea gravel), and understanding why they don’t work is critical for avoiding costly mistakes.
Topsoil, a staple of natural grass landscaping, is a disaster for artificial turf bases. It is organic, prone to settling and erosion, and compacts into a non-porous layer that eliminates drainage entirely. Standing water will pool on top of a topsoil base, weakening the turf’s backing and causing mold growth. Additionally, topsoil is a breeding ground for weeds, which will push through the turf’s backing and ruin the seamless look of your installation. Even mixing topsoil with stone will compromise the base’s stability and drainage—this is a step to avoid at all costs.
Round stones, such as river rock or pea gravel, are equally unsuitable. Unlike the angular particles of CMB and crushed granite, round stones do not lock together when compacted—they simply roll against one another, creating an unstable, shifting surface that will settle and form dips over time. While round stones are porous and offer drainage, their lack of structural stability makes them a poor choice for a turf base; the turf will shift, wrinkle, and develop uneven areas, and infill will sink into the gaps between the stones.
Other materials to avoid include clay, sand (on its own), and organic mulch—all suffer from the same flaws: poor compaction, poor drainage, or instability. Stick to CMB and crushed granite for a base that will stand the test of time.
Thickness standard for laying base layer
The ideal thickness of your artificial turf base layer is not a one-size-fits-all number—it depends on the intended use of the turf (residential, commercial, pet, high-traffic) and the native soil of your installation site (clay, sand, loam). However, Turflory has established universal thickness standards that work for 95% of installations, with minor adjustments for high-traffic or pet-specific spaces. These standards ensure the base has enough structural stability to resist settling and enough depth to act as an effective drainage layer.
For standard residential installations (backyards, patios, low-traffic landscapes) on well-draining native soil (sand or loam), Turflory recommends a total base thickness of 4–6 inches (10–15cm), split into two layers: a 3–4 inch (7.5–10cm) coarse sub-base layer (CMB or crushed granite) and a 1–2 inch (2.5–5cm) fine top base layer (decomposed granite). This thickness provides ample stability and drainage for everyday use.
For high-traffic areas (commercial plazas, playgrounds, sports fields) and pet turf installations (where quick drainage is critical), increase the total base thickness to 6–8 inches (15–20cm), with a 4–5 inch (10–12.5cm) coarse sub-base and a 2–3 inch (5–7.5cm) fine top base. The extra depth enhances drainage and compaction, making the base resistant to heavy use and quick to channel away pet urine or rainwater—perfect for Turflory’s pet turf with its advanced drainage backing.
For installation sites with poor native drainage (clay soil), add a 2-inch (5cm) layer of coarse gravel below the CMB/crushed granite sub-base to create an extra drainage layer, and stick to the 6–8 inch total base thickness for all applications. This extra gravel layer ensures water does not pool in the clay soil below the base.
In all cases, the base layer should be compacted to 95% compaction density (a professional standard) to prevent settling—this is non-negotiable for long-term flatness and stability.
Turflory's suggested grassroots construction steps
Turflory’s grassroots construction process is honed from over 10 years of manufacturing and installing high-quality artificial turf, and it is designed to be straightforward for DIY enthusiasts and professional installers alike. This step-by-step process ensures proper compaction, perfect flatness, and unimpeded drainage—applying to all Turflory products, from residential landscape turf to heavy-duty pet and commercial turf. For additional installation and maintenance guides, visit Turflory’s solution center for expert tips and troubleshooting.
Step 1: Complete site excavation and clearing
First, excavate the installation site to the depth of your intended total base thickness (4–8 inches, per the standards above). Remove all native soil, grass, weeds, roots, and debris—ensuring the excavation is level and follows a gentle 1–2% slope for additional drainage (toward natural water sources or drains). For pet turf, the slope is especially critical to speed up the drainage of pet urine and rainwater.
Step 2: Lay the optional drainage gravel layer (for clay soil)
If your native soil is clay or has poor drainage, spread a 2-inch layer of 1–2 inch coarse gravel over the excavated site and compact it lightly with a plate compactor. This creates an extra drainage layer to prevent water from pooling in the clay below.
Step 3: Install and compact the coarse sub-base layer (CMB/crushed granite)
Spread the 3–5 inch layer of 1–2 inch particle size CMB or crushed granite over the site (or gravel layer, if used). Use a landscape rake to spread the material evenly, then compact it to 95% density with a plate compactor—make multiple overlapping passes to ensure even compaction across the entire site. Check for flatness with a spirit level and add/remove material as needed to fix high or low spots.
Step 4: Add and compact the fine top base layer (decomposed granite)
Spread the 1–3 inch layer of fine decomposed granite or crushed granite (¼ inch particle size or less) over the compacted coarse sub-base. Rake it smooth to create a flawless, even surface, then compact it again to 95% density with the plate compactor—this fine layer will be the final base for laying your artificial turf, so perfection is key here.
Step 5: Final flatness and drainage check
Do a final walkthrough of the compacted base, checking for any bumps, dips, or loose areas with a spirit level and a straight 2x4 board (run the board across the base to spot unevenness). Fix any issues by adding/removing fine base material and re-compacting. Confirm the 1–2% drainage slope is still in place, and clear any debris from the base surface. Your grassroots is now complete—ready for turf laying, seaming, and infill application.
The answer to what is the best base for artificial turf is clear: a compacted layer of CMB or crushed granite, with the correct particle size, thickness, and compaction density. This base material combination delivers the perfect balance of stable foundation, unimpeded drainage, and long-term flatness—the three pillars of a successful artificial turf installation. Cutting corners on the base layer is the single biggest mistake you can make when installing synthetic grass, as it will lead to costly repairs, premature wear, and a turf that fails to live up to its potential.
Turflory’s artificial turf products—from residential landscape turf to heavy-duty pet turf—are engineered to perform at their best when paired with this science-backed base construction process. By following the guidelines in this guide, prioritizing proper ground preparation and compaction, and using the right sub-base materials, you’ll create an artificial turf installation that is not only stunning to look at but also durable, safe, and low-maintenance for 10–15 years or more.
Whether you’re a DIY enthusiast tackling a backyard project or a professional installer working on a commercial landscape, Turflory has the resources, products, and expertise to ensure your grassroots construction is done right. Explore our full range of artificial turf products, visit the solution center for more installation guides, or reach out to Turflory’s expert team for personalized base preparation advice—your perfect, long-lasting artificial turf starts with a great base.
