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reased productivity. For example, an electric handsaw can cut a 2 ×12 plank in four or five seconds, whereas it takes about a minute to do it by hand. Generally the use of power tools can increase productivity by 10 to 20 times (Walker, 1999). It must also be remembered that carpentry is a craft, therefore, the ability and experience of the carpentry can affect the productivity of the framing work and ultimately the cost for performing the work. (Calin, M 2003)
6.4 Doors and Windows
Door and windows are used to provide easy access and security to the users, while keeping unpleasant weather conditions outside and maintaining comfortable conditions inside. For these reasons, doors and windows have several components that serve various functions. (Calin, M 2003)
Major components of doors and windows basically include frames, glass, hardware, and other accessories. A frame, attached to the building structure, is used to provide support to a door or window. Hardware includes handles, hinges or butts, kick plates, locks, and bolts. Accessories a composed of weather stripping, thresholds, millions, sills, stools, locks, handles, and so on. Weather stripping is used to prevent heat loss and the intrusion of insects, dust, noise, and moisture. A threshold and a door sweep are used to prevent heat loss around the edges of the door. (Calin, M 2003)
Generally, quantity take off is simply a counting of all items required for doors and windows. Pricing provides costs of all items by multiplying each materials quantity by the unit cost of that item and totaling all materials costs. Unit costs can be obtained from the estimator’s database, suppliers, manufacturer’s catalogues, Means (1999), Walker (1999), or other sources. The estimator, however, must keep in mind that the Mean and Walker references typically contain average industry cost data, so adjustments must be made for the particular company crew and project location. Table 6.41 presents five major steps in cost estimation for doors and windows.
Table 6.41 Major Steps for Door and Window Cost Estimation
Step Description
1 Specifications and drawing
2 Takeoff pricing for doors, window, accessories (number of doors, windows)
3 Takeoff pricing for glazing (width ×height, m²)
4 Takeoff pricing for accessories (m)
5 Total costs of doors, windows
Most of the items covered in this chapter are finished by materials suppliers and installed on the job by carpenters hired by the subcontractor. In the estimate, labor costs should be included under their proper trade. Quantity take off for doors and windows means simply counting or copying all required items from the schedules and specifications to a takeoff sheet, especially for residential construction. The estimator counts the number of exterior and interior doors and lists the quantity by size, materials, unit, and installation cost.
Similarly to that for metal doors and frames, quantity take off for wood and plastic doors requires the estimator to identify openings, combine all the quantity surveys, check specially requirements, and determine accessories. For entrances and storefronts, the estimator should submit the plans and specifications to an installer for takeoff and pricing. The quantity take off for entrance units determines total length of framing, number of joints, hardware, threshold, and closers. The quantity take off for storefront units determi本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。