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

CH Inorganic clays of high plasticity, fat clays, silty clays, etc. Poor to fair Medium OH Organic silts and organic clays of high plasticity Poor to very poor Medium Peat Highly organic PT Peat and other highly organic soils Not suitable Slight TABLE 6.20 Characterics of Compacted Subgrade for Roads and Airfields (from The Unified Soil Classification System, U.S. Army, 1960) (Continued) Compressibility Drainage properties Compaction equipment Typical dry densities pcf Mg/m3 Sub. mod.,a pci Almost none Excellent Crawler-type tractor, rubber-tired roller, steel-wheeled roller Almost none Excellent Crawler-type tractor, rubber-tired roller, steel-wheeled roller Very slight to slight Fair to very poor Rubber-tired roller, sheepsfoot roller 115145 1.842.32 2060 200500 Slight Poor to very poor Rubber-tired roller, sheepsfoot roller 130145 2.082.32 2040 200500 Almost none Excellent Crawler-type tractor, rubber-tired roller 110130 1.762.08 2040 200400 Almost none Excellent Crawler-type tractor, rubber-tired roller 105135 1.682.16 1040 150400 Very slight to medium Fair to poor Rubber-tired roller, sheepsfoot roller 100135 1.602.16 1040 100400 Slight to medium Poor to very poor Rubber-tired roller, sheepsfoot roller 100135 1.602.16 520 100300 Slight to medium Fair to poor Rubber-tired roller, sheepsfoot roller 90130 1.442.08 15 or less 100200 Medium Practically impervious Rubber-tired roller, sheepsfoot roller 90130 1.442.08 15 or less 50150 Medium to high Poor Rubber-tired roller, sheepsfoot roller 90105 1.441.68 5 or less 50100 High Fair to poor Sheepsfoot roller, rubber-tired roller 80105 1.281.68 10 or less 50100 High Practically impervious Sheepsfoot roller, rubber-tired roller 90115 1.441.84 15 or less 50150 High Practically impervious Sheepsfoot roller, rubber-tired roller 80110 1.281.76 5 or less 25100 Very high Fair to poor Compaction not practical Source: U.S. Army, The Unified Soil Classification System.

thickness, in Face thickness, in Orientation Base Face Spacing, c to c, in Fasteners only Adhesive between plies a. Application in ceilings 3/8 3/8* Across Across 16 16 3/8 3/8* Across Parallel 16 1/2 3/8* Parallel Across 16 16 1/2 1/2 Parallel Across 16 16 1/2 1/2* Across Across 24 16 5/8 1/2* Across Across 24 24 5/8 1/2* Parallel Across or parallel 24 5/8 5/8 Across Across 24 24 5/8 5/8 Parallel Across or parallel 24 b. Application in walls 3/8, 1/2, 5/8 3/8 Across or parallel 16 24 3/8, 1/2, 5/8 1/2, 5/8 Across or parallel 24 24 * Gypsumboard for ceilings to receive a water-base-spray texture finish should be applied only across (perpendicular to) framing. For 16-in spacing of framing, board thickness should be increased from 3/8 to 1/2 in. For 24-in spacing of framing, board thickness should be increased from 1/2 to 5/8 in. Not recommended. and rated. Nails should penetrate at least 11/8 in into supports.With sound-deadening base plies, fastener spacing should be as recommended by the base manufacturer. In placing face ply on base ply, joints in the two layers should be offset at least 10 in. Face ply may be applied horizontally or vertically. Horizontal application (long sides of sheet perpendicular to supports) usually provides fewer joints, but vertical application may be preferred for predecorated wallboard that is to have joints trimmed with battens. 11.26.4 Finishing Procedures for Gypsumboard The finish surface of wallboard may come predecorated or may require decoration. Predecorated wallboard may require no further treatment other than at corners, or may need treatment of joints and concealment of fasteners. Corner and edge trim are applied for appearance and protection, and battens often are used for decorative concealment of flush joints. Other types of wallboard require preparation before decoration can be applied. While trim can be applied to undecorated wallboard, as for predecorated panels, usually, instead, joints are made inconspicuous. Joint-Treatment Products. Materials used for treatment of wallboard joints to make them inconspicuous should meet the requirements of ASTM C475. Application of joint treatments should conform with ASTM C840. These materials include: