Conical Roof

Ogee Roof. Shed Roof. Gable Roof. The span of a roof is the width rise is the height of the ridge the level of the supports; the pitch is the slope or angle at which it is inclined. In carpentry, roof signifies the timber framework by which the roofing or covering materials of the building are supported. This consists in general of the principal rafters, the purlins, and the common rafters. The principal raf ters, or principals, as they are commonly termed, are placed so as to span the building at intervals usually of 10 or 12 feet; the purlins lie horizontally upon these, and sustain the common rafters, which carry the covering of the roof. The accompanying figure shows one of IMG:content-2442.jpg:[blocks in formation] King-post Roof. A, king-post; B, tie-beam; C, C, struts or braces; D, D, purlins; E, E, principal rafters; F, F, common rafters; G, G, wall-plates; IH, ridge-pole. the two varieties of principals which are in common use (the king-post principal), with the purlins and common rafters in position. (For a diagram of the second, the queen-post principal, see queen - post .) Each of these modes of framing constitutes a tru . Sometimes, when the width of the building is not great, common rafters are used alone to support the roof. They are in that case joined together in pairs, nailed where they meet at the top, and connected by means of a tie at the bottom. They are then termed couples , a pair forming a couple - close . See also cuts under hammer - beam , hip - roof , jerkin -head, M- roof , pendent , and pendentive . Goodly buildings left without a roof Soon fall to ruin. Shak., Pericles, ii. 4. 36. 2. Anything which in form or position corresponds to or resembles the covering of a house, as the arch or top of a furnace or oven, the top of a carriage or coach or car, an arch or the interior of a vault, the ceiling of a room, etc.; hence, a canopy or the like. Ffor tristith, als trewly as tyllinge us helpeth, That iche rew me vndir roff of the reyne-bowe Sholde stable and stonde be these thre degres. Richard the Redele , iii. 248.