A roof form featuring one or more inclined surfaces rising to meet at a ridge, point, or wall surface. The number of surfaces and their pitch — steepness or angle of inclination — determine varied shapes and types of pitched roofs, such as gable or hipped roofs. Offering structural strength and highly effective in draining rainwater and shedding snow, they have been used across geographies since antiquity, from ancient Greek temples and medieval European churches and castles, to vernacular structures in tropical South and Southeast Asia. They have historically comprised a timber frame clad with materials such as clay or wood shingles, thatch, or skin; modern roofs use a variety of materials including concrete, steel and synthetic membranes. Colonial bungalows in tropical regions used pitched roofs to shade large, uninterrupted spaces and deep verandahs that kept the interiors cool; they became an important feature of the Tropical Modernist architecture pioneered by Sri Lankan architects such as Minnette de Silva and Geoffrey Bawa.