Backerboard: A flat material used on the face of the house, between the studs and the siding, to provide a nailable surface for the siding.

Buttlock: The bottom edge of a siding or soffit panel, or accessory piece, opposite the nailing slots, which locks onto the preceding panel.

Camber: The straightness of a vinyl siding panel.

Capstock: A thin protective layer of acrylic added to some vinyl siding products to improve weatherability and color retention.

Channel: The area of the accessory trim or corner post where siding or soffit panels are inserted. Channels also refer to the trim itself, and are named for the letters of the alphabet they resemble, i.e., J-channel, F-channel, etc.

Course: A row of panels, one panel wide, running the length of the house from one side to the other, or, in the case of vertical siding, from top to bottom.

Double Channel Lineal: A siding accessory that joins two soffit panels.

Drip Cap/Head Flashing: An accessory installed with vertical siding to ensure that water drips away from panels and does not infiltrate them; it is also used as a vertical base.

Extrusion: A manufacturing technique that forces vinyl compound through a die to create long panels or strips in various shapes and sizes. This process is used to manufacture vinyl siding panels, corner posts, soffit and other accessories, as well as other vinyl products like PVC pipes and window frames.

Face: The portion of a siding or soffit panel that is showing once the panel has been installed.

Fascia Board: A board attached to the ends of the rafters between the roofing material and the soffit overhang. Fascia cap is the covering around that board.

Flashing: A thin, flat material, usually aluminum, positioned under or behind J-channels, corner posts, windows, etc., to keep draining water from penetrating the home or building.

Furring/Furring Strip: A wooden or steel framing material, usually 1" x 3", used to provide an even nailing base. To "fur" a surface means to apply these strips.

Lap: To overlap the ends of two siding panels or accessory pieces to allow for expansion and contraction of the vinyl product.

Nailing Hem (or Flange): The section of siding or accessories where the nailing slots are located.

Soffit: Material used to enclose the horizontal underside of an eave, cornice or overhang.

Starter Strip: An accessory applied directly to the surface of the building and used to secure the first course of siding to the home.

Underlayment: Weather-resistant material placed under vinyl siding panels.

Weep Holes: Openings cut into siding or accessories to allow for water runoff.