Turf vs. concrete vs. gravel: how water actually moves
Drainage performance is about pathways and bottlenecks. Turf creates thousands of vertical flow channels through the backing into a free draining base, which spreads and moves water to an outlet. Concrete relies on surface slope to drains. Gravel can drain well, but only when it is clean and open graded.
- Artificial turf system: Water drops through the fibers and infill, passes the permeable backing, then flows through an open graded aggregate base to weep holes, perimeter drains, or daylight. Uniform flow reduces surface puddles.
- Standard concrete slab: Impermeable. Water must shed by slope into surface drains. Any birdbath or clogged drain becomes a puddle.
- Pervious concrete: Permeable by design, but prone to clogging without routine vacuuming and careful sediment control. It is a specialty option, not typical for lawns or play areas.
- Gravel: Clean, open graded stone drains well. Compacted road base with fines does not. Many gravel areas trap water because fines fill voids over time.
What controls drainage speed in a turf system
Surface and backing permeability
Perforated and fully permeable turf backings allow rapid vertical flow. Manufacturers often publish lab permeability figures in the hundreds of inches per hour for perforated backings and over a thousand inches per hour for fully permeable. Real performance is governed by the base, soil, slope, and outlet capacity.
Infill and pile height
Proper infill levels keep yarn upright and maintain open channels at the surface. Overfilled or contaminated infill can slow surface intake. Undersized pile or matted fibers can encourage sheet flow and edge puddles.
Base design and thickness
- Use an open graded aggregate base with high void content, not dense road base with fines.
- Typical landscape installs use 3 to 6 inches of open graded stone, thicker where soils are slow to drain.
- Include geotextile separation to prevent soil pumping into the base.
- Provide a positive outlet such as weep holes, French drain, or daylight.
Subgrade soil and water table
Clay soils and high water tables limit infiltration. In these cases, add underdrains or a drainage mat to move water laterally to a reliable outlet.
Slope and outlets
Base slope of 1 to 2 percent toward drains is a reliable starting point for most landscapes. On rooftops and slabs, use a drainage mat and follow the deck's designed fall to roof drains.
Design specs that keep water moving
- Choose permeable backing: Specify perforated or fully permeable turf. Confirm published permeability and warranty for your use.
- Open graded base: 3 to 6 inches of clean angular stone sized for your soil and loads. No fines.
- Separation layer: Nonwoven geotextile between soil and base to block sediment intrusion.
- Slope: 1 to 2 percent base fall toward a drain or daylight. Keep transitions smooth.
- Outlets: Perimeter weep holes, channel drains, French drains, or drain basins sized for local storm intensity.
- Edge details: Use edging that does not dam water. Add weep notches at intervals where needed.
- On concrete or rooftops: Install a drainage mat under turf and direct flow to existing surface drains.
Common mistakes that cause puddles
- Using dense road base with fines that choke voids.
- Zero slope or slope aimed away from the outlet.
- No separation fabric, allowing soil to migrate into the base.
- Trapping water with continuous edging and no weep paths.
- Undersized or clogged drain basins.
- Overcompaction of open graded base to the point of crushing stone and reducing voids.
Climate and use case notes
Heavy rain regions
Upsize outlets and base depth, and include redundant drain paths. Fully permeable backing helps clear intense downpours quickly.
Freeze and thaw
Open graded bases relieve hydrostatic pressure and reduce frost heave risk compared to ponding on slabs. Maintain outlets clear of ice and debris.
Pet areas
Permeable turf moves urine through the surface into the base. Add enzyme cleaners and ensure rapid outflow to minimize odor. A drainage mat over slabs helps airflow and drying.
Sports fields vs. lawns
Fields use engineered bases, underdrains, and laser graded slopes for predictable play and drainage. Residential and commercial lawns can adopt a simplified version of the same approach.
Rooftops and balconies
Pair turf with a high flow drain mat and respect the deck's slope to drains. Avoid adhesives that block water paths. Keep scuppers and strainers clean.
Quick decision guide
- Replacing a puddling concrete pad: Turf over drain mat with clear outlets will reduce standing water.
- Compacted gravel that stays muddy: Turf over an open graded base improves infiltration and keeps the surface clean.
- Already using pervious pavers with good maintenance: Performance is comparable. Turf may offer more uniform surface drainage.
- High water table or heavy clay: Add underdrains to move water to a reliable discharge point.
Installation checklist
- Assess soil infiltration and identify an outlet path.
- Excavate and proof roll. Install geotextile separation.
- Place and screed open graded aggregate to 3 to 6 inches. Compact to lock stone, not crush it.
- Shape 1 to 2 percent slope to drains or daylight.
- Install edging with weep gaps as needed.
- Lay turf, seam, and infill to specification. Brush to set fiber.
- Hose test. Verify flow to drains and no trapped water at edges.
Specs snapshot
- Backing permeability: Often hundreds of inches per hour for perforated, over a thousand for fully permeable. Field performance depends on base, soil, slope, and outlet.
- Base: Open graded stone, 3 to 6 inches for landscapes. Thicker or underdrains for slow soils.
- Slope: 1 to 2 percent toward drains.
- Outlets: Weep holes, basins, or daylight sized for local storm events.
