Permeable Gravel Base Guide

Why Choose a Permeable Gravel Base

Permeable gravel bases solve the problems concrete and asphalt can't:

• HOA-friendly - No "impervious surface" violations.
• Permit-friendly - Often classified as a removable improvement.
• Stormwater-compliant - Water drains straight through.
• Removable - Lift the tiles and the gravel can stay or be repurposed.
• Lower upfront cost - Typically the least expensive court base.

Recommended Specifications

The system uses three permeable fabric layers for separation, filtration, and protection:

• Fabric Layer #1 - Subgrade separator (mandatory): Non-woven permeable geotextile placed on the excavated subgrade, with 12" overlaps at seams. Keeps subsoil from migrating up into the stone base.
• Optional stabilizing fabric: Permeable woven geogrid or paver-grid placed on top of Fabric #1 - recommended for extra court stability on softer soils.
• Bottom layer (aggregate base): 4" of compacted #57 / Class 5 crushed stone (about ¾"–1" clean, angular crushed stone - ask your stone yard for "#57") placed in 2" lifts.
• Fabric Layer #2 - Intermediate separator (mandatory): Non-woven permeable geotextile between the #57 stone and the choker chip. Prevents the fine chip from migrating down into the larger stone voids.
• Choker / leveling layer: 1" of clean #8 or #9 angular stone (≈⅜" angular "chip", also called "choker stone"), screeded flat.
• Fabric Layer #3 - Top separator (mandatory): Non-woven permeable geotextile between the choker chip and the GTC tiles. Protects the underside of the tiles and keeps the chip in place.
• Edge restraint: Aluminum, steel, or PVC paver edging anchored every 12".
• Compaction: Plate compactor on each lift, finishing with the leveling chip.
• Slope: 1% (1/8" per foot) in one direction (optional - surface drains vertically).
• Flatness tolerance: 3/8" deviation over 10' straightedge.

*Permeability is officially confirmed by what your local town ordinances accept as permeable. The system described above is generally considered permeable. All fabrics specified must be permeable.

Step-by-Step Build

1. Excavate to firm, undisturbed subgrade (depth determined on-site by your contractor based on soil conditions and finished tile elevation).
2. Lay Permeable Fabric #1 - non-woven geotextile across the full footprint, lapped 12" at seams.
3. Optional - install a permeable stabilizing geogrid / paver-grid on top of Fabric #1 for extra court stability before any stone is placed.
4. Install perimeter edge restraint set to finished grade.
5. Place 4" of #57 crushed stone (¾"–1" clean angular stone) as the bottom layer, in 2" lifts, plate-compacting each lift.
6. Lay Permeable Fabric #2 - non-woven geotextile across the compacted #57 stone, lapped 12" at seams.
7. Spread the leveling chip on top of Fabric #2 - #8 / #9 stone (≈⅜" angular chip) 1" deep, screeded flat to the design slope.
8. Roll or plate-compact lightly until the surface is firm under foot.
9. Lay Permeable Fabric #3 - non-woven geotextile across the screeded chip, lapped 12" at seams.
10. Install GTC tiles directly on top of Fabric #3 - no cure time required, no rubber mat required.

Common Mistakes to Avoid

• Skipping the geotextile fabric - soil migrates up and the base settles.
• Using rounded "pea gravel" - it doesn't lock and shifts under load.
• Skipping edge restraint - the perimeter spreads and the surface collapses inward.
• Compacting in one big lift - leaves voids and causes long-term settling.
• No stabilizing grid - surface is more prone to ruts and depressions.

Cost note: Base pricing varies widely by region, site prep, accessibility, and contractor. Request quotes from local licensed contractors for an accurate estimate.