A ventilation system utilizing ventilators installed in openings in the attic and properly positioned to take advantage of natural air flow to draw hot summer or moist winter air out and replace it with fresh outside air.

A method of reroofing with new asphalt shingles over old shingles in which the top edge of the new shingle is butted against the bottom edge of the existing shingle tab.

Area unobstructed by screens, louvers or other materials.

Shingles consisting of a single, solid tab with no cutouts.

Any wood-based panel that does not contain veneer and carries an APA span rating, such as wafer board or oriented strand board.

Method of installing asphalt shingles on roof slopes between 4 inches and 21 inches per foot.