Permeable Pavers and Sustainable Hardscaping in Ontario
Much of my work focuses on native planting and ecological restoration because planting design has an enormous impact on biodiversity and environmental health. But landscapes also need to function for people. Patios, walkways, driveways, seating areas, and gathering spaces are often essential parts of how we use outdoor environments.
In my experience, the most successful landscapes tend to minimize hardscaped areas to what is genuinely functional. This usually leads not only to better ecological performance, but also to better aesthetics. Oversized patios, excessively wide walkways, or large expanses of unused paving often feel visually heavy and disconnected from the surrounding landscape. They also require significant material, labour, and environmental resources to construct.
Every hardscape material carries an ecological footprint, both in terms of embodied carbon — the emissions associated with extracting, manufacturing, and transporting materials — and in terms of how it affects water movement through a site.
In Ontario, the most common hardscape materials include concrete, asphalt, natural stone, pre-cast concrete pavers, brick pavers, and loose aggregates such as gravel or crushed granite. These materials vary dramatically in both environmental impact and performance.
Generally speaking, conventional concrete tends to have one of the highest embodied carbon footprints. Cement production is extremely energy intensive and releases large amounts of carbon dioxide during manufacturing. Concrete is durable and versatile, which is why it is so widely used for foundations, sidewalks, and structural paving, but it is also one of the least permeable materials when poured as a continuous surface.
Asphalt also carries a relatively high environmental cost because it is a petroleum product derived from oil refining. However, it remains popular because it is relatively inexpensive, fast to install, and practical for large driveways or commercial surfaces.
Pre-cast concrete pavers and manufactured slabs occupy something of a middle ground. They still rely on cement production, but because they are modular systems rather than continuous slabs, they can often be repaired, lifted, or reconfigured more easily over time. They also create opportunities for permeability when installed properly.
Brick pavers generally have a somewhat lower carbon footprint than concrete products, though they still require high-temperature kiln firing during manufacturing. They bring warmth and texture to landscapes and are often well suited for traditional or historic contexts.
Natural stone typically has lower embodied carbon than manufactured paving products because it is quarried rather than chemically manufactured. The environmental impact depends heavily on transportation distance and quarrying practices. Locally sourced stone can be a relatively durable and lower-impact option with exceptional longevity and aesthetic richness.
Loose aggregate materials such as gravel, crushed limestone, or crushed granite are often among the lowest-impact hardscape options available. They require comparatively little processing and remain fully permeable. They are also generally among the most affordable materials. Aggregates work particularly well for informal paths, secondary walkways, seating areas, and low-traffic spaces.
This brings us to one of the most important concepts in contemporary landscape design: permeability.
Permeability refers to how easily water can move through a surface and infiltrate into the soil below. In natural landscapes, rainwater is absorbed into the ground where it replenishes groundwater reserves, supports plant roots, and slowly moves through ecological systems. In heavily urbanized environments dominated by roofs, roads, and paving, water instead runs rapidly across surfaces into storm drains and sewer infrastructure. This creates several problems.
First, excessive stormwater runoff can overwhelm municipal infrastructure during heavy rainfall events. As climate change increases the frequency and intensity of storms, many cities are struggling with flooding and overloaded stormwater systems.
Second, impermeable surfaces interrupt the natural hydrological cycle. Water that could have infiltrated into the soil instead leaves the site immediately. This reduces groundwater recharge and leaves landscapes more vulnerable during periods of drought.
Third, permeable landscapes help moderate temperature. Water stored in soil and vegetation slowly evaporates during hot weather, cooling surrounding areas through evapotranspiration. Large expanses of asphalt and concrete, by contrast, absorb and radiate heat, contributing to urban heat island effects.
For these reasons, municipalities increasingly regulate the percentage of hardscape permitted on private properties. Zoning by-laws often distinguish between impermeable hardscape and permeable “softscape” areas such as gardens and lawns.
At one end of the permeability spectrum is soft landscaping itself — gardens, planting beds, meadows, and lawns — which allow the highest degree of infiltration. Loose aggregates are also highly permeable because water can move between the particles and into the ground below.
Traditional poured concrete and asphalt are essentially impermeable. Water remains on the surface and must be directed elsewhere through grading and drainage systems.
Pavers and flagstone systems exist somewhere in between. Their permeability depends largely on how they are installed. The wider the joints between individual units, the more opportunity there is for water infiltration. Equally important is the base beneath the paving. A permeable paving system requires an open aggregate base that allows water to move downward into the soil below.
Some contractors prefer installing pavers on concrete bases for stability and durability, particularly in freeze-thaw climates like Ontario. In certain situations, this may be appropriate. But it also reduces permeability significantly. There are trade-offs between durability, maintenance, cost, permeability, and aesthetics.
In recent years, manufacturers have developed specialized permeable paver systems specifically engineered to address these concerns. These products typically include larger joint spaces or integrated voids that allow water infiltration while still maintaining structural stability and interlock strength. When properly installed over an engineered aggregate base, permeable pavers can significantly reduce stormwater runoff while still providing durable and attractive surfaces.
Ultimately, there is no single “best” hardscape material for every project. The right choice depends on site conditions, budget, intended use, aesthetics, maintenance expectations, and environmental priorities.
Part of good landscape design is understanding how these materials perform over time, not only visually, but ecologically.
