wood, metal, masonry, vinyl, and other materials. Shim -- a building material used to even a surface prior to installing vinyl siding. Soffit -- material used to enclose the horizontal underside of an eave, cornice, or overhang. Soffit is designed to be installed lengthwise from wall to fascia. Starter Trim -- an accessory applied directly to the surface of the building and used to secure the first course of siding to the home. Square -- a square represents an area of 10' by 10' (100 sq. ft.) and is generally the term used in the industry v when referring to the quantity of siding. Vinyl siding is measured in squares, i.e.: this house requires 20 squares of siding. Undersill Trim -- a piece of trim used any time the top lock has been removed from the siding, to secure a siding panel. Weep Holes -- openings cut into siding or accessories to allow for water runoff. Window/Door Drip Cap -- an accessory installed with vertical siding to ensure that water drips away from panels and does not infiltrate them. Outside and Inside Corner Posts -- Corner posts are used to provide a finished edge at an inside or outside -corner. The siding from adjoining walls fits neatly into the inside or outside corner post channels. Appropriate widths of channel openings are available to accommodate various configurations of siding. Important Notes Building Codes Installers need to be aware of building code requirements in the geographic areas where they are installing, and