What is Impervious?

Impervious refers to a material, surface, or layer through which water, moisture, or other liquids cannot pass.

Definition

An impervious surface is a surface that prevents water from touching the soil underneath. If it rains on these surfaces, the water will not be absorbed by the soil and will runoff across the surface. This property of impervious materials can be beneficial in several construction applications where protection from moisture or durability and/or structural stability are required.

Purpose

The main use of impervious surfaces is to prevent unwanted water from entering. This prevents moisture-related damage, erosion, and deterioration to buildings, roads, foundations, and other structures.

For site planning, the knowledge of impervious surface covering is crucial for drainage design, stormwater control, environmental compliance and land development approvals. Many municipalities regulate the amount of impervious area allowed on a property to help reduce flooding and manage runoff.

Examples of Use

Impervious surfaces and materials are commonly used in:

Building roofs and waterproofing systems
Parking lots and roadways
Sidewalks and pedestrian pathways
Concrete slabs and foundations
Drainage and stormwater management planning
Site development and land-use assessments
Commercial, industrial, and residential construction projects

Related Terms

Stability

:

Stability is the ability to stay unchanged and remain in its position even when exposed to forces that could cause movement or change.

Usury

:

Usury is the act of charging interest on a loan at rates that are considered excessively high or unfair, often crossing the legal maximum.

Acid Rain

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Acid rain is a phenomenon that happens when air pollution mixes with rain, snow, or other moisture before falling to the ground.

Notes

Common impervious surfaces include asphalt, concrete, rooftops, metal, and paved parking areas.
Excessive impervious surface coverage can increase stormwater runoff and drainage challenges.
Site designers often measure impervious coverage when planning land development projects.

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