Impermeable means that a substance does not allow another substance to pass through it. It can refer to preventing a fluid, gas or solid from passing through.
Types of Impermeability
A hole in a wall is permeable; air, water and flies can get through. A screen is semipermeable; flies are too big to get through but air and water can. A closed window is impermeable, because glass keeps out rain and hot or cold air.
Impermeability can affect building material, allergy treatments, how your body functions and the environment.
Impermeability in Building
Vapor barriers prevent moisture condensation in walls, basements, ceilings and crawl spaces. According to the U.S. Department of Energy, vapor barriers should be on the “warm side” to make insulation more effective.
Impermeable Bed Coverings
Impermeable bed coverings keep dust mite allergens inside pillows or mattresses, although people with allergies should also use other treatments to prevent allergy symptoms, according to the New England Journal of Medicine.
Oxygen in blood passes through permeable capillaries but not impermeable arteries and veins. Cell membranes are permeable to oxygen, slightly permeable to water and impermeable to glucose.
According to the Institute of Water Research, impermeable rocks prevent ground water flow and change the beds of rivers and streams.(See References 4.)