weather-resistant barrier

a material layer or coating on the exterior of a house that repells and drains water, keeping it from entering the house. The building codes require that exterior walls be provided with a weather-resistant barrier. The barrier is installed behind the exterior veneer or cladding material. The barrier system may include flashing, sealants, water-resistant paper, and house wrap. This continuous barrier causes rain water to flow down and out. Also called "water-resistant barrier" or "water-resistant envelope."