ROOF FUNCTION To keep out rain, wind, snow & dust To prevent excessive heat loss in winter To keep the interior building cool in summer Designed to accommodate all stresses encountered Designed to accept movement due to changes in temperature & moisture content To provide lateral restraint & stability to adjacent walls To resist penetration of fire & spread of flame from external sources TYPES OF ROOF Flat Roof Its not perfectly flat Must have a slight slope for drainage Shed Roof A single slope Gable Roof 2 slope meeting at ridge. 2 walls extends to the ridge Hip Roof 2 gable, pyramid should be considered as a hip roof Gambrel Roof 4 slopes in one direction, the typical barn roof Mansard Roof 2 gambrels Basically is to the gambrel what the hip is to gable Pitched Roof drains water insulates main area of heat loss support snow load Shed roof Hip Roof Flat Roof & Pitched Roof Mansard Roof Gambrel Roof FLAT ROOF Its not perfectly flat, slightly slope which is less than 10°. This roof is been used in hot climates where water accumulation is not a problem. (less rain) PITCHED ROOF Roof whose angle of slope to the horizontal lies between 10° - 70°. Construction cost for pitched roof is higher than flat roof and more material is needed. There’s bigger space below the roof than flat roof can be made as attic. PITCHED ROOF DESIGN The slope for pitched roof depends on the rain (how heavy the rain is, frequency of the rain) in a year. In Malaysia, the roof built at West Coast Malaysia & East Coast Malaysia is different due to the factor of wind and rain. This are the names of some of the pitched roof elements which been labeled on previous slide 1. Asphalt Shingles 2. Rafter 3. Ridge 4. Valley Rafter 5. Collar Beam Ridge - spine of the roof - A pitching plate for the rafters that are nailed to each other through the ridge board Collars - Its an extra ties to give additional strength & are placed at purlins level Eaves - Eaves of a roof is the lowest edge that overhangs the wall, thus giving the wall a degree of protection - Also provides the fixing medium for the rainwater gutter. PITCHED ROOF STRUCTURE Depends on different types roof structure system, roof structure can also include the followings: a) Purlins b) Rafter c) Trusses d) Beams e) Girders Beam - member that span across the openings & support structure or loading above them. - Beam usually in timber, steel & reinforced concrete. Purlins - Act as a beam reducing the span of the rafter enabling an economic section to be used Girder - A main horizontal or near horizontal structural member that supports vertical loads. - It may consists several pieces. Rafter - One of the series of structure of a roof designed to support roof loads. - Roof structural failure usually begin with rafter deflection or rafter spread. Beams In Roof Structure Purlins In Roof Structure GIRDER Girder RAFTER TRUSS Roof structures can be formed very simply using trussed rafters. These are made from small section timber and comprise the rafters on the roof slopes, a horizontal to support the ceiling, and various combinations of cross members to form a frame or truss. RAFTER COLLAR TIE The members are usually fixed together using metal plate connectors. The trusses are designed and produced by the manufacturer to suit the span and profile of a roof. They are a very cost effective way of forming roofs of houses and are often seen on building sites. Types Of Truss Howe Truss Fink Truss Pratt Truss Warren Truss TYPES OF TRUSS a) Pitched truss b) Bowstring Truss c) Flat Truss PRINCIPAL RAFTER STRUT TIE KING POST King Post Truss .