Ground sealing & stormwater management: field solutions for compliant projects in 2026

Understanding ground: permeability, runoff, and job-site risks

What makes ground permeability vary (clay, sand, fill, compaction)

Ground permeability first depends on its texture. Clay soil lets water through slowly. Sandy soil infiltrates faster. Fill material is often heterogeneous, with layers that block water. Compaction by machinery closes up the pores and can turn decent ground into a nearly impermeable zone.

Spotting signs of runoff and stormwater pooling

On site, look for runoff paths. Rills after rain, soil displaced at the bottom of a slope, washed-out gravel. Puddles that persist for more than 24 hours, mud that sticks, or areas that stay green near downspouts indicate pooling. Also watch for moisture marks on foundation walls.

Simply measuring infiltration before starting (tests and points of attention)

Before excavating, run a simple infiltration test. Dig a hole about 30 cm deep, moisten the sides, then fill it with water and time how fast the level drops. Repeat at 2 or 3 points. If water stays for a long time, adjust your phasing, plan for stormwater management, and avoid further compaction in wet weather.

Choosing the right strategy: sealing or favoring stormwater infiltration

When ground sealing is justified (constraints, uses, safety)

You seal ground when the use requires it. Vehicle access, storage areas, accessibility ramps, or surroundings where runoff needs to stay under control. It's also relevant if the water risks carrying pollutants (oils, sludge) or if the plot infiltrates very poorly (clay, nearby water table). The goal remains simple: prevent degradation and accidents.

When to favor permeable ground (stability, drainage, comfort of use)

Permeable ground limits puddles, eases the load on networks, and improves comfort during rainy periods. Permeable pavers, stabilized gravel, grass pavers, or swales create gentle infiltration. This also helps reduce surface heating in summer, especially in courtyards and driveways.

Combining a mixed solution: sealed zones + infiltration zones

The best option is often a mixed solution. You keep sealed strips where vehicles drive and turn. You reserve the rest for infiltration. Drainage trenches, aggregate beds, rain gardens, or planted strips at the bottom of a slope. Think about slopes. Water needs to move away from walls and toward the planned zones.

Techniques and materials suited to ground: from drainage to finishing

Preparing the ground: excavation, sub-base layer, geotextile, slope management

Everything starts with proper excavation, down to stable ground. A sub-base layer (aggregate) is then applied in several passes, with careful compaction to avoid settling. A geotextile between the ground and the aggregate limits fines from rising and keeps the structure clean. Finally, levels are set with a simple, continuous slope, often around 1 to 2%, to guide the water.

Stormwater drainage systems: gutters, drains, infiltration trenches

Depending on ground permeability, you combine gutters (at the base of facades, in front of garages) and perimeter drains to capture water before it pools. Infiltration trenches are sized case by case, with gravel, geotextile, and an inspection chamber. A regular slope and accessible collection points simplify maintenance.

Surfaces and solutions: asphalt, concrete, permeable pavers, stabilized gravel, pedestal-mounted slabs

Asphalt and concrete hold up well to traffic, but they require a proper drainage layout. To let the ground breathe, permeable pavers and stabilized gravel offer more permeable solutions, provided the base is properly calibrated. Pedestal-mounted slabs suit terraces, let water through, and make later modifications easier.

Sizing and securing stormwater management in 2026

Calculating contributing surfaces and slopes: avoiding overflow

Start by adding up all the surfaces that drain to the same point (roof, terrace, driveways), then apply a coefficient based on the surface type. Then check the site's elevation. A continuous slope of 1 to 2% toward a catch basin, gutter, or swale limits standing water and water entry at thresholds. Consistent slope, no reverse slope.

Anticipating heavy rain: overflow, buffer storage, protecting buildings

Heavy rain is managed with two layers of security. Buffer storage (tank, basin, swale, trench) absorbs the peak, and an overflow directs the excess to a safe area or the network, without running near foundations. Add protection at low points (thresholds, window wells) and, where connected, a backflow valve. Secured overflow.

Maintenance and warranties: how to avoid callbacks related to ground and stormwater

Most callbacks come from clogging and silt. Plan for accessible inspection chambers, a pre-filter, and a water test at the end of the job. Provide a simple maintenance guide (clearing, checking after leaf fall). On sensitive ground, stabilize traffic areas and protect structures with geotextile to prevent settling and erosion.

Compliance points and best practices for your files and your clients

Local framework: zoning plan, on-site management, network discharge, and permits

Before proposing any works, check the local zoning plan, the stormwater zoning, and the sanitation regulations. Some municipalities require on-site management of rainwater. Infiltration, swales, permeable surfaces. Depending on the nature of the ground, a permeability test may be requested, and a network discharge agreement may be required.

Job-site traceability: plans, photos, material data sheets, and installation specifications

A clear file avoids callbacks. Keep a site plan, cross-sections, treated surface areas, and dated photos before, during, and after. Add product guides, technical data sheets, technical approvals when they exist, and installation specifications. Thickness, slope, drainage layer, network protections, and management of excavated soil.

Client talking points: comfort, ground durability, flood reduction, and property value

With the client, talk about comfort of use and maintenance. More permeable ground limits puddles and runoff, reduces overflow during storms, and protects structures over time. It's also a plus for property value, especially in areas exposed to heavy rainfall.