How drainage works on a slab
Artificial turf drains vertically through perforations in the backing. Over concrete, you need a vented separation layer so water can move horizontally to scuppers, trench drains, or perimeter exits. Drainage tiles or panels create this channel network under the turf and prevent water from getting trapped.
Site prep checklist
- Confirm slope: target at least 1 percent fall toward drains. That is roughly 1/8 inch per foot.
- Map exits: identify scuppers, trench drains, and low edges where water leaves.
- Fix birdbaths: fill low spots or saw-cut relief to a drain so water has a path.
- Clean the slab: remove grease, paint overspray, loose coatings, and debris.
- Dry fit the layout: plan turf roll direction, seams, and where tiles will terminate.
Recommended build-up assembly
1. Concrete substrate
Sound, clean, and sloped. Remove loose coatings and ensure drains are clear and accessible.
2. Drainage tiles or panels
Use interlocking vented tiles or high-flow panels designed for roof decks or sport surfaces. Install tight to drains and scuppers without blocking weeps. Leave manufacturer-specified expansion gaps at perimeter walls.
3. Optional shock pad
Add a rated pad where fall attenuation or extra comfort is required. Choose a pad that allows lateral water movement and is compatible with the tile layer.
4. Turf with perforated backing
Use a tufted, perforated product suited for rooftops, patios, or play areas. Lay rolls so the grain aligns and seams face away from the main sightline.
5. Seams and adhesive
Use turf seam tape and moisture-cured urethane adhesive. On concrete, perimeter-bond and seam-bond are common to allow drainage and thermal movement.
6. Perimeter restraint and transitions
Use low-profile edging, termination bars, or compatible metal trims. Do not seal all edges shut. Maintain clear outlets near drains and scuppers so water exits freely.
7. Infill
Top-dress with clean, rounded sand or coated mineral infill to ballast the turf, support fibers, and promote even drainage. Brush to settle.
Slope and water management
- Minimum slope: 1 percent is the practical baseline for reliable runoff on slabs.
- Measurement: use a 2 to 4 foot level and shims to verify fall. Adjust with patching compounds if needed.
- Outlets: never cover weep holes, scuppers, or drain grates. Cut clean openings in turf and tiles so water enters drains without restriction.
Step-by-step install
- Clean and dry the slab. Verify slope and drains.
- Lay drainage tiles or panels, locking them in place and trimming to fit. Keep paths open to drains.
- Dry fit turf, align pile, and trim to size with 2 to 3 inches extra at edges.
- Tape and glue seams. Roll to set. Remove squeeze-out.
- Perimeter-bond turf to concrete or termination bars where specified.
- Cut openings for drains and scuppers. Finish edges with trims that do not block water.
- Add infill and power brush to level and lift the fibers.
- Final rinse to confirm flow paths are clear.
Common mistakes to avoid
- Dead-flat slabs without a drainage layer. Always use tiles or panels if the surface lacks fall.
- Blocking scuppers or drain grates with turf or adhesive.
- Fully encapsulating the perimeter, trapping water under the system.
- Using infills that hold water or fines that can clog drains.
- Skipping expansion allowances at edges on sun-exposed decks.
Maintenance on concrete
- Keep drains and scuppers clear. Vacuum or blow debris away from outlets.
- Brush the turf as needed to redistribute infill and maintain surface evenness.
- For snow and ice, use a plastic shovel and a leaf blower. Avoid metal blades.
- Rinse periodically to move fine debris toward drains.
Use cases
- Rooftop amenity decks and balconies
- Patios, courtyards, and pool surrounds
- Converted sport or play areas built on slabs
Safety and code notes
- Rooftops and balconies: follow building, fire, and wind-uplift requirements. Use rated components where required and keep access to all roof drains.
- Guard any unprotected edges and penetrations per code. Confirm load capacity before adding system weight.
Material selection tips
- Turf: perforated backing, UV-stable yarn, and heat-tolerant construction for hardscape installs.
- Drainage layer: interlocking tiles or panels with multi-directional flow channels.
- Adhesive: moisture-cured urethane for seams and perimeter bonds on concrete.
- Infill: clean, rounded mineral infill that drains freely and provides ballast.
When to call a pro
Bring in a certified installer if you have ponding water, complex roof details, limited slope, or strict code conditions. A pro will tune the assembly to your site so water moves cleanly and the surface stays tight and safe.
