What drainage system is best under rooftop turf?

Why rooftop turf needs a dedicated drainage layer

Rooftops are low slope, not flat. Water must move quickly to drains without trapping moisture under the surface. A dedicated drainage layer creates open pathways for water and air so the roof membrane stays dry, the turf stays clean, and performance stays consistent after rain or cleaning.

• Protects the roof membrane by reducing hydrostatic pressure and trapped moisture.
• Speeds water to drains and scuppers to prevent puddling at seams and edges.
• Adds ventilation that helps the turf and infill dry faster, which supports hygiene and surface longevity.

Best options under rooftop turf

Free draining interlocking panels

Rigid panels snap together to form a continuous void space that moves water horizontally and vertically. The open grid also promotes airflow under the turf.

• Strength and stability for amenity decks with furniture and foot traffic.
• High flow capacity with multidirectional channels.
• Ventilation under the turf, which helps with heat release and faster dry times.
• Cleanable cavity for maintenance access near drains.

Dimple drain mats

Roll goods with molded dimples create a low profile air and water layer. They are light, flexible, and efficient in tight build ups.

• Lower height build up for doors and thresholds.
• Continuous pathways that move water to drains.
• Compatible with many roof protection sheets and shock pads.

Panels vs mats: how to choose

• Traffic and use: Choose panels for heavy use amenity spaces with furniture and events. Choose mats for lighter use terraces or space constrained edges.
• Build height: Use mats where every millimeter matters. Use panels where 0.75 to 1.25 inches of height is available.
• Ventilation and dry time: Panels generally circulate more air under the turf. That helps surfaces dry faster after rain or cleaning.
• Access to drains: Panels make it easier to create access paths and inspection points to roof drains.
• Budget: Mats are often lower material cost. Panels can reduce long term maintenance by improving dry time and access.

Installation essentials for rooftop assemblies

Protect the roof first

• Confirm the roof type and warranty requirements with the roofing manufacturer.
• Install an approved separation or protection sheet over the membrane before the drainage layer.
• Avoid penetrations. Use perimeter restraints designed for rooftop systems.

Promote flow to drains

• Lay panels or mats so channels run toward drains and scuppers.
• Keep drain inlets and cleanouts accessible with removable turf or access tiles.
• Feather transitions so water does not pond at panel edges or thresholds.

Edge and seam strategy

• Use perimeter edging that allows water and air to move while containing infill.
• Stagger panel seams and tape mat seams as specified to prevent vertical telegraphing.
• Do not block scuppers or overbuild at parapets.

Design and compliance checklist

• Roof slope: Verify positive slope to drains throughout the area.
• Fire performance: Use components with appropriate fire classification for roof decks.
• Wind uplift: Follow ballast or attachment guidelines for the climate zone and building height.
• Weight and loading: Confirm structural capacity for turf, infill, drainage layer, furniture, and occupants.
• Warranty alignment: Ensure every layer is approved by the roofing manufacturer.

Performance and maintenance

• Keep drains clear. Schedule routine inspections and debris removal.
• Rinse and sanitize as needed, especially in pet zones. The ventilation layer helps surfaces dry faster after cleaning.
• In snow regions, use plastic shovels or a snow blower with skids set high to protect the turf.

Common mistakes to avoid

• Skipping the drainage layer, which slows dry time and stresses the membrane.
• Using solid foam without engineered channels that allow lateral flow and ventilation.
• Blocking drain access with continuous base or perimeter build ups.
• Overfilling with fine infill that can migrate into channels. Choose clean, well graded infill and use geotextile where specified.

Typical rooftop turf build ups

• Turf with infill
• Free draining interlocking panels or dimple drain mat
• Protection sheet approved by roofing manufacturer
• Roof membrane
• Insulation or cover board as existing
• Structural deck

Cost overview

• Drainage layer materials: Dimple mats are typically lower cost per square foot than interlocking panels.
• Installed system: Total installed cost varies by access, height limits, edge details, and code requirements. Panels can reduce maintenance cost by improving dry time and access to drains.

How FusionTurf helps

We match your project goals to the right drainage layer, provide build up details the roofer will sign off on, and support your install team with clear, job ready instructions. Share your plans and we will specify a rooftop system that drains fast, dries quickly, and keeps Artificial turf looking and playing its best.