In Southern Italy , the prevalent type of dwelling is the single-storey rural home. Very common in Campania, Basilicata and Calabria, this consists in a single ground-floor room, often above or below street level. The trullo or conical dwelling of Apulia is a descendant of the circular single-room day shelter with roof of stone slabs. In its most common form, the trullo is a single-storey independent building with a rectangular ground plan and a conical roof above each internal division. It is thus the outcome of the merging of a series of round buildings with tapering roofs designed to serve as living quarters or as farm buildings.
As a result of the abundance of sunshine in the south and the consequent desire for outdoor life, combined with the need to keep the house as cool as possible indoors, many houses are provided with porticoes, terraces, roof-gardens or pergolas. All of these features lend themselves to the essentially geometric shape.
Tufa is widely used in Naples and Bari. It may be suitably used for walling, within a framework of reinforced concrete, since the climate is mild, and snow and heavy rain are rare, the soil rests on a limestone deposit or is very permeable and of volcanic origin. In view of the existence of a dry season, especially in the south and on the island, the storage of water is a necessity. This explains the wide use of the typical flat or vaulted roof. Which is certainly a basic feature in the designing of these houses intended to allow of optimum adaptation to arid climatic conditions.