Permeable pavements for flood resilience

Permeable pavements are an engineered approach to nature-based solutions. These surfaces allow stormwater to pass through the pavement into the underlying ground, reducing runoff and flood risk. They increase resilience by managing stormwater locally, improving water quality and decreasing stress on drainage infrastructure. For small and rural communities, permeable pavements provide a low-maintenance flood resilience strategy for roads, sidewalks, parking areas and public spaces.

This guidance outlines key steps, best practices, costing information and case studies to help municipalities plan and deliver permeable pavement projects.

Key steps for successful implementation

• Assess site suitability: Consider traffic volume, presence of utilities, slope, drainage and soil infiltration rates
• Consider the appropriate pavement surface type: Select the most suitable surface out of porous asphalt, pervious concrete or permeable interlocking concrete pavement (PICP)
• Get your paperwork in order: Seek required permits and approvals from environmental and municipal authorities

Best practices for design and delivery

• Take protective measures during installation: Preserve surface pore space during installation by minimizing compaction and restricting traffic for 24–48 hours post-installation
• Install a defensive layer: Incorporate underdrains or liners where soils have low infiltration to protect groundwater and utilities
• Design for winter¹ climates: Apply larger aggregates in pervious concrete to reduce freeze–thaw damage in cold climates; prevent clogging by choosing clean gravel instead of sand or salt for winter conditions
• Conduct routine maintenance²: Be consistent with sweeping and vacuuming to remove surface debris, and pressure washing for persistent clogging, to maintain the integrity of the pavement

Equity and community considerations

• Design pedestrian paths and parking areas to be accessible: Avoid uneven settlement of the pavement surface and limit large gaps, using contrasting colours to facilitate access for wheelchair users and people with mobility aids
• Consider safety in design: Ensure materials offer sufficient traction to avoid slips and falls, especially for older adults and people with mobility challenges
• Prioritize installation in areas with the greatest need: Reduce flood risk and polluted runoff in neighbourhoods with inadequate or aging stormwater systems, including low-income areas experiencing disproportionate impacts.

Costing and budgeting information

Permeable pavement projects can cost $50–$150 per square metre depending on site conditions and the permeable system chosen. Additional costs can arise when deeper bases, underdrains or liners are required to meet infiltration or structural needs.

Typical cost drivers include materials, subgrade preparation, drainage design and maintenance.

To help reduce overall costs:

• Prioritize small-scale pilot areas with lower costs before investing in larger deployment
• Plan for regular maintenance to prevent clogging and extend lifespan
• Enlist the help of residents and volunteer groups for routine maintenance (e.g., Adopt a Street programs), such as sweeping and removing trash and weeds

Case studies and lessons learned

Tailoring permeable pavement materials to site conditions (Vaughan, ON, 2015)

Researchers at the University of Guelph, in collaboration with the Sustainable Technologies Evaluation Program (STEP), monitored three permeable pavement types (pervious concrete and two types of permeable interlocking concrete pavers) in a parking lot to evaluate long-term runoff reduction, water quality improvements and thermal effects compared with traditional asphalt. Over three years, researchers assessed the performance and durability of each material under a variety of conditions, including winter weather and different maintenance practices.

The results revealed a variety of insights. For example, permeable interlocking concrete pavers require more frequent cleaning while pervious concretes may leach materials into stormwater outflow that are undesirable for aquatic ecosystems.

Lesson learned: Give careful consideration to the type of permeable pavement material selected for the project site. A thorough evaluation of the site’s drainage patterns, traffic use, surrounding vegetation, temperature extremes and cleaning practices can help communities determine the most appropriate materials for their context. This will enhance the pavement’s performance and lifespan.

Public engagement drives behavioural change for green infrastructure (Sackville, NB, 2024)

A de-paving project led by EOS Eco-Energy, a local non-profit, transformed a section of asphalt measuring 30 square metres into a permeable pavement area in a parking lot at a park. This allowed rainwater to infiltrate naturally while filtering pollutants before they could reach local waterways.

Leading up to and during the project, EOS implemented a communications strategy to educate the public and local municipalities about de-paving, stormwater management and low-impact development practices. The strategy combined media outreach, site tours, social media campaigns (#RainAsAResource) and hands-on workshops.

Lesson learned: Integrating public outreach and education into infrastructure projects can catalyze community awareness, behavioural change and adoption of green infrastructure practices, amplifying the impact of small-scale pilot projects beyond their physical footprint.

Revitalizing underused spaces through permeable surfaces (London, ON, 2024)

Fanshawe College transformed its underused Arts Courtyard by removing 118 square metres of asphalt and creating a naturalized area with permeable surfaces and native plantings, including a rain and pollinator garden. The college recycled the removed asphalt and incorporated permeable materials made from recycled tires. The project reduced runoff, improved stormwater infiltration and restored habitat for native wildlife.

Lesson learned: De-paving and greening neglected or underutilized areas can simultaneously restore natural hydrology, enhance biodiversity, and create community spaces that are accessible and functional. This demonstrates revitalization’s value in terms of both ecological and social benefits.

*Note: The case studies included on this page are for informational purposes and were not supported by the Green Municipal Fund.

Additional resources

Permeable pavement site sustainability evaluation tool (Applied Research Associates) –This Excel-based tool helps users evaluate and rank up to six potential sites for permeable pavement based on feasibility and suitability. The tool generates scores categorizing sites as amenable, marginal or unsuitable, supporting informed decision-making for project scoping.

Design guidelines for low-impact development permeable pavement (City of Calgary) –This technical guidance document supports the design of permeable pavement systems for residential and commercial developments. Appendix A includes a detailed design checklist covering site feasibility, system selection, hydrology and structural design. Appendix B provides an example.

Stormwater manual (City of Seattle) – Appendix G of this manual provides technical guidance on inspection, maintenance and operational requirements for permeable pavement. It outlines recommended inspection frequency, common defects, maintenance triggers and expected outcomes to ensure long-term performance of permeable pavement..

Explore more flood resilience activities

Learn about other flood resilience project types and how they can support your community:

• Wetland restoration or construction
• Stormwater ponds

Return to the Flood Resilience Toolkit for Municipalities

Related toolkits

GMF offers additional toolkits to support municipalities facing different climate risks. 

• Heat Resilience Toolkit
• Wildfire Resilience Toolkit
• Community Facilities Toolkit

Glossary

Aggregate: Crushed stone or gravel used in the base or surface of permeable pavements to provide structural support and facilitate water infiltration

Drainage: The controlled movement of stormwater through and away from a site, often managed through permeable pavement layers, underdrains or surface channels

Hydrology: The study of water movement, distribution and quality in a given area, including rainfall, runoff and groundwater flow

Permeable interlocking concrete pavement (PICP): A type of pavement made of interlocking blocks with void spaces that allow water to infiltrate, often filled with gravel or soil

Permeable pavements: Engineered surfaces designed to allow stormwater to pass through, reducing runoff and flood risk while improving water quality

Pervious concrete: Concrete mix with reduced fine aggregates to create a porous matrix that allows water infiltration

Porous asphalt: Asphalt mix with reduced fine aggregates to allow water to pass through the surface into underlying layers

Runoff: Water that flows over surfaces instead of infiltrating, often carrying pollutants into stormwater systems or natural waterways

Soil infiltration rate: The speed at which water can soak into the soil, influencing how quickly permeable pavements can drain stormwater

Stormwater management: Practices that control the quantity and quality of runoff from rain or snow, often to reduce flooding and improve water quality

Subgrade: The native soil or prepared layer beneath the pavement base that provides structural support for the pavement system

Surface pore space: The small voids or openings on the pavement surface that allow water to pass through into underlying layers

Underdrains: Perforated pipes installed beneath permeable pavements to facilitate drainage where soils have low infiltration rates or where water must be directed to an outlet to the underlying ground, reducing runoff and flood risk. They increase resilience by managing stormwater locally, improving water quality and decreasing stress on drainage infrastructure. For small and rural communities, permeable pavements provide a low-maintenance flood resilience strategy for roads, sidewalks, parking areas and public spaces.

Select resources

1. LID - Permeable Pavements Factsheet

2. Permeable-Pavement-Fact-Sheet.pdf