c. Use of ledger plates. In connecting
joists to girders and sills where piers are used, a
narrow piece of 2-inch lumber is nailed to the face of
the sill or girder, flush with the bottom edge; this is
called a "ledger plate" (fig. 1-32). These pieces
should be nailed securely with 20-penny nails about
12 inches apart. Where 2 x 6 or 2 x 8 joists are used,
it is better to use 2 x 2's to prevent the joists from
splitting at the notch. When joists are 10 inches deep
or deeper, 2 x 4's may be used without reducing the
strength of the joists. If a notch is used, joist ties may
be used to overcome this loss of strength, as shown in
figure 1-2. These ties are short 1 x 4 boards nailed
across the joist; the ends of the boards are flush with
the top and bottom edges of the joists.
Figure 1-32. Ledger plates (or strips).
Figure 1-33. Types of bridging.
joists. Each piece is nailed to the top of each joist
1-33. BRIDGING
and forms a cross between the joists. These pieces
When joists are used over a long span they have
between joists should be placed as near to each other
a tendency to sway from side to side. Floor frames
as possible. Bridging should be nailed with two 8- or
are bridged in order to stiffen the floor frame, to
10-penny nails at each end. The tops should be
prevent unequal deflection of the joists, and to enable
nailed and the bottoms left with nails driven through
an overloaded joist to receive some assistance from
the bridging only until the subfloor or finish floor is
the joists on either side of it. Bridging is of two kinds
laid. This permits the joists to adjust themselves to
horizontal bridging (1, fig. 1-33) and cross bridging
their final positions. The bottom ends of bridging
(2, fig. 1-33). Cross bridging is the one most
may then be nailed, forming a continuous truss across
generally used; it is more effective and requires less
the whole length of the floor and preventing any
material than horizontal bridging. Cross bridging
overloaded joist from sagging below the others.
looks like a cross and consists of pieces of lumber,
Cutting the bridging by hand is a slow process; on
usually 1 x 3 or 2 x 3, put in diagonally between the
large jobs a power saw should be used if it is
floor
available. After the joists have once been placed, a
pattern may be made and used to speed up the
process of cutting. On joists more than 8 feet long,
one
1-35
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