Permeable Resin-Bound Surfacing in Raleigh, NC

UDO Article 9.2 and the Neuse nitrogen limit

Raleigh's stormwater rules sit in Article 9.2 of the Unified Development Ordinance, which requires stormwater control measures, watercourse buffers or both before land disturbance or subdivision. The code lists permeable pavement as a primary stormwater control measure, provided it is designed, built and maintained to the NCDEQ minimum design criteria. Section 9.2.2 caps nitrogen export from new development or expansion at 3.6 pounds per acre per year, allows the balance to be offset through payments to the state Riparian Buffer Restoration Fund or private mitigation banks, and holds peak runoff for the 2-year and 10-year storms to pre-development rates.

The City's Stormwater Design Manual and related UDO changes took effect on November 2, 2024. Parts of north Raleigh drain to Falls Lake, which has its own nutrient strategy on top of the Neuse rules, so confirm early which applies to the site.

Under the state criteria, the finished permeable surface must show an infiltration rate of at least 50 inches per hour, and any surface other than pavers, pervious concrete or porous asphalt must be backed by evidence of long-term hydraulic and structural performance.

Piedmont clay, sandier ground to the east and the stone reservoir

Raleigh sits near the eastern edge of the Piedmont, with clay subsoils across much of the city and sandier ground toward eastern Wake County. That range is why the state criteria require a site-specific soil investigation for any infiltrating design and at least two feet between the bottom of the subgrade and the seasonal high water table, reducible to one foot only with a hydrogeologic evaluation. If soils cannot drain the design volume within 72 hours, an underdrained detention design is the fallback.

Two more criteria often decide residential and small commercial jobs. The soil subgrade must be nearly flat, at 2 percent or less, so sloping drives in older neighborhoods may need terraces under the surface. Run-on from other hard surfaces is limited to a 1:1 ratio, so a permeable strip at the foot of a long concrete drive can only accept so much. Older commercial lots along corridors such as Capital Boulevard should be checked for contaminated fill before anyone plans infiltration.

Where it fits in Raleigh

• Homeowner driveways and walkways inside city limits, the uses Raleigh Rainwater Rewards names for permeable pavement.
• Downtown and Glenwood South patios and courtyards, where a primary SCM has to fit inside a small footprint.
• Nonprofit and place-of-worship driveways and walkways, which may fit the Rainwater Rewards subsidy track if City staff approve the design.
• Campus and government grounds with pedestrian plazas and a facilities team to handle sweeping.

Rainwater Rewards, permits and Resin Rock's role

For existing properties, Raleigh Rainwater Rewards lists permeable pavement for driveways and walkways among its eligible projects. The standard program pays 90 percent of project costs, and a subsidy track pays 100 percent for owners in underserved communities, nonprofits and places of worship. Properties must be inside city limits and pay the stormwater fee, and the process starts with a consultation request and a site visit. Whether a resin-bound design qualifies is the City's decision.

For development, permeable pavement is reviewed with the site's stormwater plan under Article 9.2 and the design manual. Resin Rock supplies binder, stone blends, trims and the Rock Crete permeable sub-base, publishes technical data sheets for the review package, and trains and approves installers; we do not install. To refinish existing concrete instead, see concrete resurfacing in Raleigh. For a permeable build, request an approved installer.