Weatherization is the practice of protecting a building and its interior from outside elements, such as sunlight, precipitation, and wind, and modifying a building to reduce energy consumption and optimize energy efficiency.

Typical weatherization procedures include:

• Sealing recessed lighting fixtures which leak large amounts of air into unconditioned attic space.
• Sealing bypasses--cracks, gaps, and holes-- around doors, windows, pipes and wiring that penetrates the ceiling and floor, as well as other areas with a high-potential for heat loss. Typical materials used are caulk, foam sealant, weather-stripping, window film, door sweeps, or electrical receptacle gaskets.
• Sealing air ducts using reinforced mastic. Air ducts account for 20% of heat loss.
• Protecting pipes from corrosion and freezing.
• Installing or replacing dampers in exhaust ducts. This prevents outside air from entering the house when the exhaust fan or clothes dryer is not in use.
• Providing proper ventilation to unconditioned spaces to protect a building from the effects of condensation.
• Installing footing drains, foundation waterproofing membranes, interior perimeter drains, sump pump, gutters, downspout extensions, downward-sloping grading, swales, or French drains. This protects a building from both surface water and ground water.
• Installing storm doors and storm windows.
• Installing roofing, building wrap, siding, flashing,, skylights or solar tubes, and making sure they are in good condition on an existing building.
• Installing insulation in walls, floors, and ceilings, around ducts and pipes, around water heaters, and near the foundation and sill.
• Replacing older windows with low-energy, double-glazed windows.
• Replacing old drafty doors with tightly-sealing, foam-core doors.