Building Design and Construction Handbook - Merritt - Ventech!

BUILDING SYSTEMS 1.13
may be encased in fire-resistant floors, roofs, or walls. Similarly, columns may be
encased in walls, and beams may be encased in floors. Or a fire-resistant material,
such as concrete, mineral fiber, or plaster, may be used to box in the structural
members (Fig. 1.6c).
See also Secs. 7 to 11.
Systems for Enclosing Buildings. Buildings are enclosed for privacy, to exclude
wind, rain, and snow from the interior, and to control interior temperature and
humidity. A single-enclosure type of system is one that extends continuously from
the ground to enclose the floor. Simple examples are cone-like tepees and dome
igloos. A multiple-enclosure type of system consists of a horizontal or inclined top
covering, called a roof (Fig. 1.1), and vertical or inclined side enclosures called
walls.
Roofs may have any of a wide variety of shapes. A specific shape may be
selected because of appearance, need for attic space under the roof, requirements
for height between roof and floor below, desire for minimum enclosed volume,
structural economy, or requirements for drainage of rainwater and shedding of snow.
While roofs are sometimes given curved surfaces, more often roofs are composed
of one or more plane surfaces. Some commonly used types are shown in Fig. 1.4.
The flat roof shown in Fig. 1.4a is nearly horizontal but has a slight pitch for
drainage purposes. A more sloped roof is called a shed roof (Fig. 1.4b). A pitched
roof (Fig. 1.4c) is formed by a combination of two inclined planes. Four inclined
planes may be combined to form either a hipped roof (Fig. 1.4d) or a gambrel roof
(Fig. 1.4e). A mansard roof (Fig. 1.4ƒ) is similar to a hipped roof but, composed
of additional planes, encloses a larger volume underneath. Any of the preceding
roofs may have glazed openings, called skylights (Fig. 1.4b), for daylighting the
building interior. The roofs shown in Fig. 1.4c to ƒ are often used to enclose attic
space. Windows may be set in dormers that project from a sloped roof (Fig. 1.4c).
Other alternatives, often used to provide large areas free of walls or columns, include
flat-plate and arched or dome roofs.
Monitored roofs are sometimes used for daylighting and ventilating the interior.
A monitor is a row of windows installed vertically, or nearly so, above a roof (Fig.
FIGURE 1.4 Roofs composed of plane surfaces: (a) flat roof; (b) shed roof; (c) pitched roof;
(d) hipped roof; (e) gambrel roof; (ƒ) mansard roof; (g) monitored roof; (h) sawtooth
roof. (Reprinted with permission from F. S. Merritt and J. Ambrose, ‘‘Building Engineering and
Systems Design,’’ 2d ed., Van Nostrand Reinhold, New York.)