Figure 6-15.-Types of sills.
Other types of sill framing and layout are
shown in figure 6-15.
Horizontal members that support the floors
in wood frame structures are called JOISTS or
BEAMS, depending upon the length of the SPAN
(distance between the end supports). Members less
than 4 ft apart are called joists; members 4 ft or
more apart are called beams. The usual spacing
for wood frame floor members is either 16 in. or
24 in. O.C. Joists are usually 2 by 8, 2 by 10, or
2 by 12. A COMMON JOIST is a full-length joist
that spans from wall to wall or from wall to
girder. A CRIPPLE JOIST is similar to a
common joist with the exception that it does not
Figure 6-16.-Spaced wood girder.
extend the full span. Cripples are normally
interrupted by floor openings.
Girders (fig. 6-16) are horizontal members that
support joists at points other than along the outer
wall lines. When the span is longer than can
be covered by a single joist, a girder must
be placed as an intermediate support for joist
ends. Ground-floor girders are commonly
supported by concrete or masonry pillars and
pilasters. A PILLAR is a girder support that is
clear of the foundation walls. A PILASTER is
set against a foundation wall and supports the end
of a girder. Both pillars and pilasters are
themselves supported by concrete footings.
Upper-floor girders are supported by columns.
GIRTS are horizontal wood framing members
that help to support the outer-wall ends of upper-
floor joists in balloon framing.
Framing Around Floor Openings
A common joist must be cut away to give way
for floor openings, such as stairways. The wall-
opening ends of cripple joists are framed against
HEADERS, as shown in figure 6-17. Specifica-
tions usually require that headers be doubled
sometimes tripled. Headers are framed bet ween
the full-length joists, also called TRIMMERS, on
either side of the floor opening. Headers up to
6 ft in length are fastened with nails, whereas
those longer than 6 ft are fastened with joist