Pitched Roof By 131170106063 PATEL ANKITKUMAR H

INTRODUCTION A roof may be defined as the uppermost part of the building, provided as a structural covering, to protect the building from weather (i.e. from rain, sun, wind etc). A roof consists of structural elements which support roof coverings. The structural elements may be trusses, portals, beams, slabs(with or without beams), shells or domes. The roof coverings may be A.C sheets, G.I sheets, wooden shingle, tiles, slates or slab itself.

REQUIREMENTS OF A ROOF It should have adequate strength and stability to carry the super-imposed dead and live loads. It should effectively protect the building against rain, sun, wind, etc. and it should be durable against the adverse effects of these agencies. It should be waterproof and should have efficient drainage arrangements. It should provide adequate thermal insulation. It should be fire resistant. It should provide adequate insulation against sound. Most forms of roof construction provide for majority of buildings an adequate insulation against sound from external sources.

TYPES OF ROOFS Roofs may be divided into three categories: Pitched or sloping roofs Flat roofs or terraced roofs Curved roofs The selection of the type of roof depends upon The shape or plan of the building & Importance of the building Climatic conditions of the area and Type of constructional materials available

ELEMENTS OF PITCHED ROOF SPAN: It is the clear distance between the supports of an arch, beam or roof truss. RISE: It is the vertical distance between the top of the ridge and the wall plate. PITCH: It is the inclination of the sides of a roof to the horizontal plane. It is expressed either in terms of degrees(angle) or as a ratio of rise to span. RIDGE: It is defined as the apex line of the sloping roof. It is the apex of the angle formed by the termination of the inclined surfaces at the top of a slope . EAVES: The lower edge of the inclined roof surface is called eaves. From the lower edge(eaves), the rain water from the roof surface drops down.

HIP: It is the ridge formed by the intersection of two sloping surfaces, where the exterior angle is greater than 180 degrees. VALLEY: It is a reverse of a hip. It is formed by the intersection of two roof surfaces, making an external angle less than 180 degrees. HIPPED END: It is the sloped triangular surface formed at the end of a roof. VERGE: The edge of a gable, running between the eaves and ridge, is known as a verge. RIDGE PIECE, RIDGE BEAM OR RIDGE BOARD: It is the horizontal wooden member, in the form of a beam or board, which is provided at the apex of a roof truss. It supports the common rafters fixed to it. PURLINS: These are horizontal wooden or steel members, used to support common rafters of a roof when span is large. Purlins are supported on trusses or walls .

RAFTERS: COMMON RAFTERS OR SPARS: These are inclined wooden members running from the ridge to the eaves. They are bevelled against the ridge beam at the head, and are fixed to purlins at intermediate point. They support the battens or boarding to support the roof coverings. Depending upon the roof covering material, the rafters are spaced 30 to 45 cm centre to centre HIP RAFTERS: These are the sloping rafters which form the hip of a sloped roof. They run diagonally from the ridge to the corners of the walls to support roof coverings. They receive the ends of the purlins and ends of jack rafters. JACK RAFTERS: Any rafter which is shorter than a common rafter is known as a jack rafter. PRINCIPAL RAFTER: These are inclined member of a truss.

EAVES BOARD OR FACIA BOARD: It is a wooden plank or board fixed to the feet of the common rafters at the eaves. It is usually 25 mm thick and 25 mm wide. The ends of lower most roof covering material rest upon it. The eaves gutter, if any, can also be secured against it. BARGE BOARD: It is a timber board used to hold the common rafter forming verge. WALL PLATES: These are long wooden members, which are provided on the top of stone or brick wall, for the purpose of fixing the feet of the common rafters. These are embedded from sides and bottom in masonry of the walls, almost at the centre of their thickness. Wall plates actually connect the walls to the roof. JACK RAFTERS: These are the rafters shorter in length, which run from hip or valley to the eaves.

BATTENS: These are thin strips of wood, called scantlings, which are nailed to the rafters for lying roof materials above. BOARDINGS: They act similar to battens and are nailed to common rafter to support the roofing material. TEMPLATE: This is a square or rectangular block of stone or concrete placed under a beam or truss, to spread the load over a larger area of the wall. CLEATS: These are short sections of wood or steal (angle iron), which are fixed on the principal rafters or trusses to support the purlins. TRUSS: A roof truss is a frame work, usually of triangles, designed to support the roof covering or ceiling over rooms.

PITCHED ROOFS A roof with sloping surface is known as a pitched roof. They are basically of the following forms: lean-to-roof Gable roof Hip roof Gambrel roof Mansard or curb roof Deck roof

LEAN-TO-ROOF: This is the simplest type of sloping roof, provided either for a room of small span, or for the verandah. It has slope only one side. GABLE ROOF: This is the common type of sloping roof which slopes in two directions. The two slopes meet at the ridge. At the end face, a vertical triangle is formed.

HIP ROOF: This roof is formed by four sloping surfaces in four directions. At the end faces, sloped triangles are formed. GAMBREL ROOF: This roof, like gable roof, slopes in two directions, but there is a break in each slope. At each end, vertical face is formed.

MANSARD ROOF: This roof, like a hip roof, slopes in four directions, but each slope has a break. Thus, sloping ends are obtained. DECK ROOF: A deck roof has slopes in all four directions, like a hip roof, but a deck or plane surface is formed at the top.