3.
4.
5.
6.
Figure 1-32.—Types of framing anchors.
Place the outside pieces between the inside
trimmers. Drive three 16d nails through the
trimmers into the headers. Mark the position of
the tail joists on the headers (the tail joists should
follow the regular joist layout).
Fasten the tail joists to the outside headers with
three 16d nails driven through the headers into
the ends of the tail joists.
Double the header. Drive three 16d nails through
the trimmer joists into the ends of the doubled
header pieces. Nail the doubled header pieces to
each other with 16d nails staggered 16 inches
OC.
Double the trimmer joists and fasten them
together with 16d nails staggered 16 inches OC.
A pair of joists, called trimmers, is placed at each
side of the opening. These trimmers support the headers.
The headers should be doubled if the span is more than
4 feet. Nails supporting the ends of the headers are
driven through the trimmer joists into the ends of the
header pieces. Tail joists (cripple joists) run from the
header to a supporting wall or girder. Nails are driven
through the header into the ends of the tail joist. Various
metal anchors, such as those shown in figure 1-32, are
also used to strengthen framed floor openings.
Crowns
Most joists have a crown (a bow shape) on one side.
Each joist should be sighted before being nailed in place
to make certain the crown is turned up. The joist will
later settle from the weight of the floor and straighten
out. Caution should be exercised when sighting the
board for the crown. Some crowns are too large and
cannot be turned up for use as a joist.
SUBFLOOR
The subfloor, also known as rough flooring, is
nailed to the top of the floor frame. It strengthens the
entire floor unit and serves as a base for the finish floor.
The walls of the building are laid out, framed, and raised
into place on top of the subfloor.
Panel products, such as plywood, are used for
subflooring. Plywood is less labor intensive than board
lumber.
Plywood is the oldest type of panel product. It is still
the most widely used subfloor material in residential and
other light-framed construction. Other types of material
available for use as subflooring include nonveneered
(reconstituted wood) panels, such as structural
particleboard, waferboard, oriented strandboard, and
compositeboard.
Plywood is available in many grades to meet abroad
range of end uses. All interior grades are also available
with fully waterproof adhesive identical with that used
in exterior plywood. This type is useful where prolonged
moisture is a hazard. Examples are underlayments,
subfloors adjacent to plumbing fixtures, and roof
sheathing that may be exposed for long periods during
construction. Under normal conditions and for
sheathing used on walls, standard sheathing grades are
satisfactory.
Plywood suitable for the subfloor, such as standard
sheathing, structural I and II, and C-C exterior grades,
has a panel identification index marking on each sheet.
1-16
