Copyright Goodheart-Willcox Co., Inc.
262 Section 2 Foundations and Framing
Main ceiling framing members are called ceiling joists.
Their size is determined by the span and spacing. To
coordinate with walls and permit the use of a wide
range of surface materials, a spacing of 16″ OC is com-
monly used. Size and quality requirements must also
be based on the type of ceiling finish (plaster or dry-
wall) and how the attic space will be used. Generally,
2×6s may be used for spans of less than 12′ and 2×8s
for spans under 14′. Spaces with larger spans usually
have roof trusses, which permit such spans. The archi-
tectural plans usually include the specifications. These
requirements should be checked with local building
codes.
Ceiling joists usually run across the narrow dimen-
sion of a structure. However, second-floor joists can
also be supported by bearing walls. This makes the span
even shorter and may result in ceiling joists perpendic-
ular to each other in the same frame, Figure 11‑37.
In large rooms, the midpoint of the joists may need
to be supported by a beam. This beam can be located
below the joists or installed flush with the joists. In a
flush installation, the joists may be carried on a led-
ger or by joist hangers. Sometimes a beam is installed
above the joists in the attic area. It is tied to the joists
with metal straps.
At their outer ends, the upper corners of ceiling joists
need to be cut at an angle to match the slope of the
roof. To lay out the pattern for this cut, use the framing
square as shown in Figure 11‑38. When the amount of
stock to be removed is small, the cuts can be made after
the joists and rafters are in place.
Parallel Ceiling Joists
When ceiling joists run parallel to the edge of the
roof, the outside member is likely to interfere with the
roof slope. This often occurs in low-pitched hip roofs.
The ceiling frame in this area should be constructed
with stub joists running perpendicular to the regular
joists, Figure 11‑39.
Lay out the position of the ceiling joists along the
top plate. When a double plate is used, the joists do
not need to align with the studs in the wall. The layout,
however, should put the joists alongside the roof rafters
so that the joists can be nailed to them. Ceiling joists
are installed before the rafters unless the assembly is
prefabricated. Toenail ceiling joists to the plate using
two 10d nails on each side.
Install backing for
nailing ceiling surface
material on this section
of top plate
Nailer
Double top
plate
Load-bearing
partitions
Goodheart-Willcox Publisher
Figure 11‑37. A ceiling frame. The joists in the foreground are turned at right angles to reduce the span.
Height of rafter back at
outside of double plate
Unit run Mark and cut
along this
edge Unit rise
Ceiling joist
Goodheart-Willcox Publisher
Figure 11‑38. A framing square is used to lay out the trim
cut on the end of a ceiling joist. Using the rise and run of
the building, the cut matches the slope of the rafters.
262 Section 2 Foundations and Framing
Main ceiling framing members are called ceiling joists.
Their size is determined by the span and spacing. To
coordinate with walls and permit the use of a wide
range of surface materials, a spacing of 16″ OC is com-
monly used. Size and quality requirements must also
be based on the type of ceiling finish (plaster or dry-
wall) and how the attic space will be used. Generally,
2×6s may be used for spans of less than 12′ and 2×8s
for spans under 14′. Spaces with larger spans usually
have roof trusses, which permit such spans. The archi-
tectural plans usually include the specifications. These
requirements should be checked with local building
codes.
Ceiling joists usually run across the narrow dimen-
sion of a structure. However, second-floor joists can
also be supported by bearing walls. This makes the span
even shorter and may result in ceiling joists perpendic-
ular to each other in the same frame, Figure 11‑37.
In large rooms, the midpoint of the joists may need
to be supported by a beam. This beam can be located
below the joists or installed flush with the joists. In a
flush installation, the joists may be carried on a led-
ger or by joist hangers. Sometimes a beam is installed
above the joists in the attic area. It is tied to the joists
with metal straps.
At their outer ends, the upper corners of ceiling joists
need to be cut at an angle to match the slope of the
roof. To lay out the pattern for this cut, use the framing
square as shown in Figure 11‑38. When the amount of
stock to be removed is small, the cuts can be made after
the joists and rafters are in place.
Parallel Ceiling Joists
When ceiling joists run parallel to the edge of the
roof, the outside member is likely to interfere with the
roof slope. This often occurs in low-pitched hip roofs.
The ceiling frame in this area should be constructed
with stub joists running perpendicular to the regular
joists, Figure 11‑39.
Lay out the position of the ceiling joists along the
top plate. When a double plate is used, the joists do
not need to align with the studs in the wall. The layout,
however, should put the joists alongside the roof rafters
so that the joists can be nailed to them. Ceiling joists
are installed before the rafters unless the assembly is
prefabricated. Toenail ceiling joists to the plate using
two 10d nails on each side.
Install backing for
nailing ceiling surface
material on this section
of top plate
Nailer
Double top
plate
Load-bearing
partitions
Goodheart-Willcox Publisher
Figure 11‑37. A ceiling frame. The joists in the foreground are turned at right angles to reduce the span.
Height of rafter back at
outside of double plate
Unit run Mark and cut
along this
edge Unit rise
Ceiling joist
Goodheart-Willcox Publisher
Figure 11‑38. A framing square is used to lay out the trim
cut on the end of a ceiling joist. Using the rise and run of
the building, the cut matches the slope of the rafters.