Conical Roof (Turret Roof)

A conical roof, also called a cone roof, rises from a circular base to a single point. It is the natural roof for round buildings and towers, and appears in a remarkable range of traditions, from medieval castle turrets to vernacular dwellings.

Where it is found

• Turrets and towers: conical roofs, often steep and clad in slate or metal, crown castle towers in France, Scotland and Germany and the corner turrets of Queen Anne and Châteauesque houses in North America.
• Trulli of Apulia, Italy: small dry-stone huts with conical corbelled stone roofs.
• East Asia: conical roofs appear on some Chinese pavilions, for example at the Nanhai Academy in Taipei.
• Round huts: thatched conical roofs over circular walls are traditional in many parts of Africa and Asia, as well as in reconstructed prehistoric roundhouses in Europe.

Construction

Framed conical roofs use rafters radiating from a central point to a circular wall plate, sometimes with a central post. Masonry versions are corbelled, with each course projecting slightly inward. Coverings must be adapted to a surface that tapers to a point: slates and shingles are cut narrower toward the top, metal is laid in tapered gores or segments, and thatch is thinned and bound at the apex. A finial or cap usually seals the tip.

Practical notes

• The steep pitch sheds water and snow quickly.
• Gutters around a curved eave must be curved or segmental.
• The apex is the most difficult point to keep watertight and is often covered by a lead or copper cap.
• Ventilating the small space under a conical roof requires care.