Roof Ridge

The ridge is the highest horizontal edge of a pitched roof, formed where two slopes rise to meet. Every gable, hip or similar roof has at least one ridge; complex roofs may have several at different heights. The term covers both the external line of the roof and, loosely, the framing member beneath it.

Structure

Beneath the ridge, opposing rafters meet against a ridge board or ridge beam, or the top chords of trusses meet at the apex. Historic roofs might have a ridge piece carried by a king post, or no ridge timber at all.

Covering the ridge

Because the roof covering cannot simply be lapped over the apex, the ridge is finished with a separate cap:

• Ridge tiles: half-round, angled or decorative tiles used on clay, concrete and slate roofs. Traditionally bedded in mortar; modern UK practice increasingly uses dry-fix ridge systems in which the tiles are mechanically fixed.
• Ridge cap shingles: cut or purpose-made shingles bent over the ridge and nailed, each lapping the next, on asphalt shingle roofs.
• Metal ridge caps: formed sheet metal over metal roofs, sealed with closures that match the panel profile.
• Thatch ridges: a separate layer of thatch, often decoratively patterned, on thatched roofs.

Ventilation at the ridge

The ridge is the natural outlet for warm, moist air rising in a roof space, so it is a preferred location for exhaust vents. Continuous ridge vents cut a slot along the deck and cover it with a vented cap. US code allows a reduced total vent area where between 40% and 50% of the ventilation is placed in the upper part of the roof, within 3 ft (914 mm) of the ridge, with the rest at the eaves. UK cold roof guidance often calls for high-level ventilation equivalent to a 5 mm continuous slot at the ridge.

Terminology

The ends of a ridge meet gables or hips. In Britain, the decorative pieces at ridge ends are finials or ridge ends.