Types of roofs

The roofs classified into the following three categories;

(i) Pitched roofs

(ii) Flat roofs

(iii) Curved roofs

Pitched roofs: A sloping roof is known as pitched roof as

shown in the fig below. The technical terms in connection with

the pitched roof are given below

Flat Roofs: A roof which is nearly flat is known as flat roof. It should be noted that no roof can be laid perfectly level. The roof must slope in one direction or the other to cause rain water to

flow off rapidly and easily. The construction of flat roof is same

as that of floors except that the top surface is made slightly.

Curved roofs: These are the just the modifications of pitched roofs and are frequently employed in modern age to cover large areas shed/roofs and domes are the varieties of curved roofs. They are useful for big structures such as factories, monumental works etc curved roofs may be constructed of timber or R.C.C. the latter material being very common now-a-days. They are two common forms of a shell roof

Trussed roofs: When the span exceeds 4.8m and when there are no inside supporting walls or partitions for purlins, framed structure known as trusses are on the roof, position of cross walls, span and material of the truss. The spacing is 3m for wooden trusses. Trusses carry the ridge piece and purlins on which the common rafters rest. Some of the usual forms of roof truss are given below.

a) King-post trussb) Queen post trussc) Mansard trussd) Truncated trusse) Bel-fast trussf) Steel trussesg) Composite trusses