The roof is one of the most important parts of a building and protects the inhabitants from rain, snow, sunlight, extremes of temperature, and wind. It is made from timber framing and takes a variety of forms. The construction of the roof reflects the skill and knowledge of the Carpentry trade. Different Carpentry careers focus on specific areas of a house or building. A Joiner creates precise joints that allow for a minimum of movement, a Trim Carpenter specialises in moldings and trim like mantles, door casings, and cabinetry, while a Framer is responsible for the skeleton of the building including joists and beams. Roof framing is a very specialised area and requires knowledge of roofs, shingles, cladding, insulation and construction specifications. A traditional pitched roof is formed from inclined rafters that meet at the apex. Wider roof spans require extra support and a more sophisticated structure, such as a trussed roof. To create a truss roof, the king post is fixed to two principal rafters at wall plate level, and a spreader plate or collar tie is added to provide a bearing point for the rafters on their mid-span. Ceiling joists are then fixed to the ceiling trusses and form the ceiling plasterboard on which the ceiling is fixed. A ridge board is then laid over the trusses to complete the roof frame and act as a barrier against inclement weather. Struts are then nailed into the ceiling joists to stiffen them and prevent sagging, and they may also be braced with herringbone struts for additional strength. roof carpentry
