Civil-grade permeable pavement for municipal pedestrian routes

Lift selection guide

Lift thickness affects load tolerance, base preparation requirements, and installed cost. Choose based on route type and expected traffic — not just budget.

Lift thickness does not substitute for base preparation. All three lifts require a properly graded open-graded aggregate base. Base depth is specified per project based on soil conditions and drainage requirements. See installation guidelines in the spec pack.

CP uses standardized neutral aggregate blends. For curated stone palettes and design-led environments, see AP series →

Specifier FAQ

Questions from municipal engineers, parks departments, and landscape architects before the spec is written.

• How does CP compare to asphalt on a cost-per-SF basis?+
  CP's installed cost is typically $14–$20/SF, compared to $8–$14/SF for asphalt and $12–$20/SF for concrete. CP costs more per square foot than asphalt — that's honest. The case for CP is not cost parity; it's what you avoid: stormwater infrastructure, long-term maintenance, and ADA remediation on a surface that degrades at grade transitions. For routes where permeability is required by code or preferred by the program, CP eliminates the need for separate drainage infrastructure, which often changes the total project cost picture. Request a budget estimate for your specific project scope.
• Is CP approved for use on ADA-required accessible routes?+
  CP is designed to be firm and stable when properly installed, which are the ADA surface requirements for accessible routes. The permeable system does not compromise surface stability. Cross-slope must not exceed 2% and running slope must comply with applicable accessibility standards — these are field conditions, not material properties. The specifier and contractor are responsible for verifying that the installed system meets local ADA requirements for the specific route. Slip resistance (ASTM E303) is completed and included in the spec pack.
• How does CP perform in freeze-thaw climates?+
  The permeable system drains vertically, which removes the subsurface water that causes freeze-thaw heave in conventional impervious pavement. Because water doesn't pond beneath the surface, the primary freeze-thaw failure mode for asphalt and concrete is largely eliminated. The SBR rubber component also provides flexibility that accommodates minor substrate movement without cracking. That said, Flexus is manufactured in Atlanta and our installed base is concentrated in the Southeast — we are honest that we have limited long-term field data in harsh freeze-thaw climates. Consult with us before specifying in Zone 5 or colder environments.
• Can CP be used on a multi-use path shared by cyclists?+
  CP is designed and tested for pedestrian routes only. Shared-use paths that include cyclists, particularly at higher volumes or speeds, introduce loads and surface wear patterns outside our tested parameters. We do not recommend specifying CP as the primary surface for a high-volume multi-use path. Low-frequency cycling on a path that is primarily pedestrian — a nature trail where cyclists occasionally ride — is a different condition and can be discussed on a project-specific basis. Contact us with your project details before specifying for mixed-use applications.
• What is the maintenance requirement after installation?+
  CP requires minimal routine maintenance compared to gravel or asphalt. There is no migration to redistribute, no crack sealing, and no patching of thermal expansion joints. Routine maintenance consists of clearing debris that could accumulate in the open aggregate surface (leaves, silt in high-runoff areas) and periodic inspection of edge restraints. In areas with heavy leaf fall or silt-laden runoff, surface permeability can decline over time — low-pressure rinsing or light surface agitation restores drainage. A maintenance protocol is included in the installation guidelines.
• What is the expected service life?+
  We design for a service life of 15–20 years in properly installed and maintained pedestrian applications. Actual longevity depends on traffic load, base stability, climate, and maintenance practices. This projection is based on binder system performance data, comparable installations, and accelerated UV testing (ASTM G154) — not decade-long field data from this specific product. Flexus is a new product in a new category. We will publish updated service life data as installed projects age and we build a field record.
• Is Flexus CP available with a CSI specification?+
  Yes. CSI-formatted specification language for CP is available as part of the full spec pack, on request. Formatted for Division 32. Editable for project-specific requirements including lift selection, base specification, and edge restraint conditions. The spec pack also includes product overview, installation guidelines, cross-section details, and all ASTM and EPA testing reports. Request through the Resources page or contact us directly.