Building Design and Construction Handbook - Merritt - Ventech!

WALL, FLOOR, AND CEILING SYSTEMS 11.127
11.74). Thus, hinges applied to the edge of a door have come to be known as butts,
or butt hinges.
Butts are mortised into the edge of the door. They are the type of hinge most
commonly used in present-day buildings.
Sizes of butt hinges vary from about 2 to 6 in, and sometimes to 8 in. Length
of hinge is usually made the same as the width; but they can be had in other widths.
Sometimes, on account of projecting trim, special sizes, such as 4 1 ⁄2 � 6 in, are
used.
For the larger, thicker, and heavier doors receiving high-frequency service, and
for doors requiring silent operation, bearing butts (Fig. 11.73) or butts with Oilite
bearings or other antifriction surfaces are generally used. It is also customary to
use bearing butts wherever a door closer is specified.
Plain bearings (Fig. 11.74) are recommended for residential work. The lateral
thrust of the pin should bear on hardened steel.
Unusual conditions may dictate the use of extra-heavy hinges or ball bearings
where normal hinges would otherwise be used. One such case occurred in a group
of college dormitories where many of the doors developed an out-of-plumb condition
that prevented proper closing. It was discovered that the students had been
using the doors as swings. Heavier hinges with stronger fastenings eliminated the
trouble.
Two-bearing and four-bearing butt hinges should be selected, as dictated by
weight of doors, frequency of use, and need for maintaining continued floating,
silent operation. Because most types of butt hinges may be mounted on either righthand
or left-hand doors, it should be remembered that the number of bearing units
actually supporting the thrust of the vertical load is only one-half the bearing units
available. With a two-bearing butt, for example, only one of the bearings carries
the vertical load, and with a four-bearing butt, only two carry the load. It should
be noted, however, that some hinges (Fig. 11.72) are ‘‘handed’’ and must be specified
for use on either a right-hand or left-hand door.
When butts are ordered for metal doors and jambs, ‘‘all machine screws’’ should
be specified.
Location of Hinges. One rule for locating hinges for ordinary doors is to allow
5 in from rabbet of head jamb to top edge of top hinge and 10 in from finished
floor line to bottom hinge. The third hinge should be spaced equidistant between
top and bottom hinges. Another location for hinges is that of the standard steel
frame and door (Fig. 11.63). The location varies a little among door manufacturers,
but each is perfectly satisfactory from a functional standpoint.
Types of Hinge Pins. A very important element in the selection of hinges is the
hinge pin. It may be either a loose pin or a fast pin.
Loose pins are generally used wherever practicable, because they simplify the
hanging of doors. There are four basic pin types:
1. Ordinary loose pins
FIGURE 11.73 Bearing butt hinge. FIGURE 11.74 Plain bearing butt hinge.