For asphalt foundations, contractors should pay particular attention to:

• Aggregate gradation
• Asphalt mix
• Layer thickness
• Compaction
• Surface flatness
• Drainage slope
• Temperature during installation
• Long-term deformation

A high-quality asphalt surface can provide a suitable foundation for artificial turf, but the asphalt must be properly compacted and sufficiently stable before turf installation.

Again, a generic “95% compaction” figure should not replace the project’s engineering specification and testing requirements.

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8. Flatness Is One of the Most Important Acceptance Criteria

For non-infill turf, flatness deserves particular attention.

A commonly referenced project tolerance may be around:

3 mm over a specified straightedge length

but the exact requirement varies by sport, country, and project specification.

For professional football facilities, the applicable FIFA requirements and project documentation should take precedence over a generic internet specification.

The important principle is:

Measure the base before installing the turf—not after problems become visible.

Areas that exceed the permitted tolerance should be corrected through appropriate grinding, leveling, patching, or reconstruction before turf installation.