Other types of hinges include some with a spring that closes the door. They may be either single- or double-acting. The spring may be incorporated in a hinge mounted on the door in the usual manner, or it may be associated with a pivot at the bottom of the door. In the latter case, the assembly may be of the type that is mortised into the bottom of the door, or it may be entirely below the floor. These include overhead closers, either surface-mounted or concealed, and floortype closers. These are some of the hardest-worked items in most buildings. To FIGURE 11.77 Door-closer spring closes the door, while a hydraulic mechanism (cylinder with piston) keeps the door from slamming. get the most satisfactory operation at low first cost and low maintenance cost, each closer should be carefully selected and installed to suit the particular requirements and conditions at each door. Most of these devices are a combination of a springthe closing element and an oil-cushioned piston, which dampens the closing action, inside a cylinder (Fig. 11.77). The piston operates with a crank or a rack-and-pinion action. It displaces the fluid through ports in the cylinder wall, which are closed or open according to the position of the piston in the cylinder. Opening of the door energizes the spring, thus storing up closing power. Adjustment screws are provided to change the size of the ports, controlling flow of fluid. This management makes the closer extremely responsive to the conditions of service at each individual door and permits a quiet closure, which at the same time ensures positive latching of the door. While the fluid type of closer is preferred, pneumatic closers are also used, particularly for light doors, like screen doors. Overhead door closers are installed in different ways, on the hinge side of the door or on the top jamb on the stop side of the head frame or on a bracket secured to the door frame on the stop side. Various types of brackets are available for different conditions. Also, when it is desired to install a closer between two doors hung from the same frame, or on the inside of a door that opens out, an arrangement with a parallel arm makes this possible. Other types of closers may be mortised into the door or housed in the head above the door. Closers may be semiconcealed or fully concealed. Total concealment greatly enhances appearance but certain features of operation are limited. An exposed-type closer should be mounted on the hinge side or stop side of the door unless there is real need for a bracket or parallel-arm mounting. Whereas the use of brackets reduces headroom and may become a hazard, a parallel-arm closer mounted on the door rides out with the door, leaving the opening

Modulus of rupture, extreme fiber in bending, psi Extreme fiber in bending Fb, psi Modulus of elasticity E, psi Compression parallel to grain Fc, psi Cedar, northern white 4000 1540 600,000 740 Cedar, western red 6000 1850 900,000 1030 Douglas fir 8000 2700 1,500,000 1360 Hemlock, western 7400 2380 1,300,000 1250 Larch, western 8400 2940 1,500,000 1500 Pine, jack 6600 2100 1,100,000 1100 Pine, lodgepole 6600 1820 1,100,000 980 Pine, ponderosa 6000 1710 1,000,000 920 Pine, red or Norway 6600 2100 1,300,000 1020 Pine, southern 8000 2740 1,500,000 1360 * Air-dried prior to treatment. Based on American National Standard Specifications and Dimensions for Wood Poles, ANSI 05.1- Based on ASTM D 2899-95, Tentative Method for Establishing Design Stresses for Round Timber Piles. tration of 3% in solution. To minimize end cutting and field treatment of footing plates, these members may be extended past the corners of the foundation. Only corrosion-resistant fasteners should be used in wood foundations. To keep the interior of the foundation walls dry, it is necessary to enclose the exterior with a waterproofing membrane, such as polyethylene film, and to ensure good drainage. For the latter purpose, the ground surface should be sloped away from the building at 1/2 in / ft for a distance of at least 6 ft and gravel should be placed against the walls and under the cellar floor. (See Permanent Wood Foundation SystemTechnical Report 7 American Forest & Paper Association; Permanent Wood FoundationsDesign and Construction Guide, Southern Forest Products Association, for additional information.) Wood poles and posts are used for various types of construction, including flagpoles, utility poles, and framing for buildings. These employ preservatively treated round poles or posts with square or rectangular cross sections that are set into the ground as columns. The ground furnishes vertical and horizontal support and prevents rotation at the base. Post frame construction is used extensively in agricultural buildings and in many commercial and industrial building applications. In buildings with post frame and pole construction, a bracing system is often provided at the top of the poles or posts to reduce bending moments at the base and to distribute loads. Design of buildings supported by poles or posts without bracing requires good knowledge of soil conditions, to eliminate excessive deflection or sidesway. For allowable foundation and lateral pressures, see the applicable

Load-bearing and non-load-bearing stud walls may be built of wood, aluminum, or cold-formed steel. Basic framing consists of vertical structural members, or studs, seated on a bottom, horizontal, bearing member, called a sole plate, and capped with a horizontal tie, called a top plate (Fig. 11.16). In addition, diagonal and horizontal bracing may be applied to the framing to prevent racking due to horizontal forces acting in the plane of the wall. The studs usually are spaced 16 or 24 in on centers. Traditional surfacing materials are manufactured to accommodate these spacings; for example, panels to be attached to the framing usually come 48 in wide. (Inasmuch as the panels are fastened to each stud, panel thickness required, and hence cost, is determined by the stud spacing and generally is larger for 24-in spacing than for 16-in. Overall wall cost, however, may not be larger for the wider spacing, because it requires fewer studs.) FIGURE 11.17 Erection of a preassembled stud wall. (U.S. Gypsum Company.) Wood stud walls are normally built of nominal 2
4-in lumber. This type of construction, usually used for residential buildings, is described in Art. 10.25. Advantages of wood construction include light weight and ease of fabrication and assembly, especially in the field. Aluminum and cold-formed steel construction offer the advantages over wood of incombustibility and freedom from warping, shrinking, swelling, and attack by insects. Studs may be provided with punched openings, which not only reduce weight but also permit passage of pipe and conduit without the necessity of drilling holes in the field. Stud spacing usually is 24 in, rather than 16 in, to reduce the number of studs required. Metal framing is not so easy to cut and fit in the field as wood. Hence, prefabrication of metal walls in convenient lengths is desirable. Metal members are manufactured with a variety of widths, leg dimensions, lengths, and thicknesses. Steel studs, for example, are available as C shapes, channels and nailable sections; that is, attachments can be nailed to the flanges. Widths range from 1/2 to 6 in, and lengths, from 6 to 40 ft. For partitions, a nonstructural interior finish, such as gypsum plaster, gypsumboard, fiberboard, or wood paneling, may be applied to both faces of stud-wall framing. For exterior walls, the interior face may be the same as for partitions, whereas the outer side must be enclosed with durable, weather-excluding materials, such as water-resistant sheating and siding or masonry veneer. For quick assembly, stud walls may be prefabricated. Figure 11.17 illustrates erection of a cold-formed steel stud wall that has been preassembled with sheathing