Figure 1-68.Backing for nailing joists to ceiling frame.
Ceiling joists should be placed directly above the
studs when the spacing between the joists is the same as
between the studs. This arrangement makes it easier to
install pipes, flues, or ducts running up the wall and
through the roof. However, for buildings with walls
having double top plates, most building codes do not
require ceiling joists to line up with the studs below.
If the joists are being placed directly above the
studs, they follow the same layout as the studs below
(fig. 1-66, view A). If the joist layout is different from
that of the studs below (for example, if joists are laid out
24 inches OC over a 16 inch OC stud layout), mark the
first joist at 23 1/4 inches and then at every 24 inches
OC (fig. 1-66, view B).
It is a good practice to mark the positions of the roof
rafters at the time the ceiling joists are being laid out. If
the spacing between the ceiling joists is the same as
between the roof railers, there will be a rafter next to
every joist. Often, the joists are laid out 16 inches OC
and the roof rafters 24 inches OC. Therefore, every other
rafter can be placed next to a ceiling joist.
All the joists for the ceiling frame should be cut to
length before they are placed on top of the walls. On
structures with pitched-roofs,
joists should also be trimmed
the outside ends of the
for the roof slope. This
angle must be cut on the crown (top) side of the joist.
The prepared joists can then be handed up to the
Builders working on top of the walls. The joists are
spread in a flat position along the walls, close to where
the y will be nailed. Figure 1-67 shows one procedure
for constructing the ceiling frame. In this example, the
joists lap over an interior partition. Refer to the figure
study the following steps:
Measure and mark for the ceiling joists.
Install the ceiling joists on one side of the
Install the ceiling joists on the opposite side of
Place backing on walls running parallel to the
Install 2 by 4 blocks flat between joists where
needed to fasten the tops of inside walls running
parallel to the joists.
Cut and frame the attic scuttle.
Place strongbacks at the center of the spans.
The tops of walls running in the same direction as
the ceiling joists must be securely fastened to the ceiling
frame. The method most often used is shown in figure
1-68. Blocks, 2 inches by 4 inches, spaced 32 inches OC,
are laid flat over the top of the partition. The ends of