Deck/sheathing: The surface, usually plywood or oriented strand board (OSB), to which roofing materials are applied.

Dormer: A small structure projecting from a sloped roof, usually with a window.

Drip edge: A pre-formed strip (usually metal) with a drip leg that is installed along roof edges to allow water run off to drip clear of the deck, eaves and siding.

Eave: The horizontal lower edge of a sloped roof.

Fascia: A flat board, band or face located at a cornice's outer edge.

Felt/underlayment: A sheet of asphalt-saturated material (often called tar paper) used as a final back-up layer of protection for the roof deck.

Fire rating: System for classifying the fire resistances of various materials. Roofing materials are rated Class A, B or C, with Class A materials having the highest resistance to fire originating outside the structure.

Flashing: a water impervious component used to 1) diverts water away from openings in- or vulnerable areas of- the enclosure, and/or 2) directs water from behind cladding in an assembly to the exterior.  In a roof assembly, flashing is oftern sheet metal or rubberized membrane material. In a roof, flashing is used around any intersection or projection in a roof system, such as vent pipes, chimneys, valleys and joints at vertical walls.

Louvers: Slatted devices installed in a gable or soffit (the underside of eaves) to ventilate the space below a roof deck and equalize air temperature and vent residual moisture.