WALLS AND PARTITIONS
Once the floor is in place, it is used to support the wall frame. Wall
framing (Figure 6-28) consists of studs, diagonal bracing, cripples, trimmers;
headers, and fire blocks. It is supported by the floor sole plate. The
vertical members of the wall framing are the studs. They support the top
plates and the upper part of the building, or everything above the top
plate line. Studs support the lath, plaster, and insulation on the inside
and wall sheathing on the outside.
Walls and partitions, which are classed as framed constructions, are
composed of studs. Studs are usually closely spaced, slender, 2 x 4 vertical
members. They are arranged in a row with their ends bearing on a long
horizontal member called a bottom plate or sole plate, and their tops
are capped with another plate, called a top plate. Double top plates are
used to tie walls and partitions together. The bearing strength of stud
walls is determined by the strength of the studs. Figure 6-29, page 6-24,
shows a typical wall construction.
Partition walls divide the inside space of a building. In most cases,
these walls are framed as part of the building. Where floors are to be
installed, the partition walls are left unframed.
The two types of partition walls are bearing and nonbearing. The bearing
type supports ceiling joists; the nonbearing type supports only itself,
and may be put in at any time after the other framework is installed.
Only one cap or plate is used. A sole plate should be used in every case,
as it helps distribute the load over a larger area.
Partition walls are framed the same as outside walls; door openings
are framed as outside openings. Where there are corners or where one partition
wall joins another, corner posts or Tposts are used as in the outside
walls. These posts provide nailing surfaces for the inside wall finish.
Partition walls in a TO one-story building may or may not extend to the
roof. The top of the studs has a plate when the wall does not extend to
the roof. If the wall extends to the roof, the studs are joined to the
A corner post forms an inside corner and an outside corner which provides
a good nailing base for inside wall coverings. Figures 6-30, page 6-24,
and 6-31, page 6-25, show two of the most common types of corner posts
as they would appear constructed. The studs used at the corners of frame
construction are usually built up from three or more ordinary studs to
provide greater strength. These built-up assemblies are called corner
posts. They are set up, plumbed, and temporarily braced. Corner posts
may also be made in any of the following ways (Figure 6-32):
· A 4x 6 with a 2 x 4 nailed on the board side, flush with one
edge (Figure 6-32, A). This type of corner is for a 4-inch wall. Where
walls are thicker, heavier timber is used.
· A 4 x 4 with a 2 x 4 nailed to each of two adjoining sides (Figure
· Two 2 x 4s nailed together with blocks between them and a 2 x
4 flush with one edge (Figure 6-32, C). This is the most common method.
· A 2 x 4 nailed to the edge of another 2 x 4, the edge of one
flush with the side of the other
(Figure 6-32, D). This type is used extensively in the TO where no inside
finish is needed.
There are two types of partition
posts—T-posts and double Tposts.
Whenever a partition meets
another wall, a stud wide
enough to extend beyond the
partition on both sides is used.
This provides a solid nailing
base for the inside wall finish.
This type of stud is called a T-
post and is made in any of the following ways (Figure
· A 2 x 4 may be nailed and centered on the face side
of a 4 x 6 (Figure 6-33, A).
· A 2 x 4 may be nailed and centered on two 4 x 4s
nailed together (Figure 6-33, B).
· Two 2 x 4s may be nailed together with a block
between them and a 2 x 4 centered on the wide side
(Figure 6-33, C).
· A 2 x 4 may be nailed and centered on the face side
of a 2 x 6, with a horizontal bridging nailed behind
them to give support and stiffness (Figure 6-33, D).
When a partition is finished on one side only, the
partition post used is a simple stud, set in the outside
wall, in line with the side of the
partition wall, and finished as shown
in Figure 6-34, page 6-26. These posts
are nailed in place along with the
corner posts. The exact position of the
partition walls must be determined
before the posts are placed. When
walls are more than 4 inches thick,
wider timber is used.
In special cases (for example, where
partition walls cross), a double T-post
is used. It is made as described above,
and by nailing another 2 x 4 to the
opposite wide side, as shown in Figure
6-34, A, B, and C (C is the most
After the sills, plates, and braces are
in place and the window and door
openings are laid out, the studs are
placed and nailed with two 16d or 20d
nails through the plates. The
remaining studs are laid out on the
sills or soles by measuring, from one
corner, the distances the studs are to
be set apart. Studs are normally
spaced 12, 16, or 24 inches on center,
depending upon the outside and
inside finish material. If vertical
siding is used, studs are set wider apart since the horizontal girts between
them provide a
To double the post of the door opening, the outside studs are first
placed into position and
nailed securely. Then short studs (or trimmers) the size of the vertical
opening are cut and nailed to the inside face of the outside studs as
shown in Figure 6-35 on the sole plate. The sill of a window opening must
be framed. This sill is specified single or double. When it is double,
the top header is nailed to the opening studs at the correct height and
the trimmer next. The sill headers are toenailed to the trimmer. The door
header is framed as shown in Figure 6-35. The jack stud rests on the sole
Girts are always the same width as the studs and are flush with the
face of the stud, both outside and inside. They are used in hasty construction
when the outside walls are covered with vertical siding. Studs are placed
from 2 to 10 feet apart, with girts spaced about 4 feet apart, running
horizontally between them. The vertical siding acts in the same way as
the studs and helps carry the weight of the roof. This type of construction
is used extensively in the TO.
TOP PLATE AND SOLE PLATE
The top plate ties the studding together at the top
and forms a finish for the walls. It supports the lower ends of the roof
rafters. The top plates serve as connecting links between the wall and
the roof, just as the sills and girders are connecting links between the
floors and the walls. The plate is made up of one or two pieces of framing
lumber the same size as the studs.
If the studs at the end of the building extend to the rafters, no plate
is used at the end of the building. When used on top of partition walls,
the plate is sometimes called the cap. Where the plate is doubled, the
first plate or bottom section is nailed with 16d or 20d nails to the top
of the corner posts and to the studs. The connection at the corner is
made as shown in Figure 6- 36. After the single plate is nailed securely
and the corner braces are nailed into place, the top part of the plate
is nailed to the bottom section with 10d nails. The plate may be nailed
over each stud or spaced with two nails every 2 feet. Care must be taken
to make sure all joints are staggered. The edges of the top section and
the corner joints are lapped.
All partition walls and outside walls are finished either with a 2 x
4 or with a piece of lumber the same thickness as the wall. This lumber
is laid horizontally on the floor or joists. It carries the bottom end
of the studs, and is called the sole or sole plate. The sole should be
nailed with two 16d or 20d nails at each joist it crosses. If it is laid
lengthwise on top of a girder or joist, it should be nailed with two nails
every 2 feet.
Frame walls are bridged, in most cases, to make them more sturdy. There
are two methods of bridging—horizontal or diagonal (Figure 6-37).
Horizontal bridging is nailed
between the studs horizontally
and halfway between the sole and
top plates. This bridging is cut to
lengths that correspond to the
distance between the studs at the
bottom. Such bridging not only
stiffens the wall but also helps
Diagonal bridging is nailed
between the studs at an angle. It
is more effective than the
horizontal type since it forms a
continuous truss and keeps the
walls from sagging. Whenever
possible, interior partitions and
exterior walls should be bridged
PLUMBED POSTS AND
After the corner post, T-post, and
intermediate wall studs have been
nailed to the plates or girts, the
walls must be plumbed and
straightened so that permanent
braces and rafters may be
installed. This is done by using a
level or plumb bob and a chalk
There are two methods for plumbing posts.
Method 1. To plumb a corner with a plumb bob—
Step 1. Attach a string to the bob. The string should be long enough
to extend to or below the bottom of the post.
Step 2. Lay a rule on top of the post so that 2 inches of the rule extend
over the post on the side to be plumbed.
Step 3. Hang the bob line over the rule so that the line is 2 inches
from the post and extends to the bottom of it, as shown in Figure 6-38.
Step 4. With another rule, measure the distance from the post to the
center of the line at the bottom of the post. If it does not measure 2
inches, the post is not plumb.
Step 5. Move the post inward or outward until the distance from the
post to the center of the line is exactly 2 inches, then nail the temporary
brace in place.
Step 6. Repeat this procedure from the other outside face of the post.
The post is then plumb.
NOTE: This process is carried
out for each corner post of the
building. If a plumb bob or
level is not available, use a
rock, half-brick, or small piece
Method 2. An alternative method
of plumbing a post is shown in the
inset in Figure 6-38. 1b use this
Step 1. Attach the plumb-bob
string securely to the top of the
post to be plumbed. Be sure that the
string is long enough to allow
the plumb bob to hang near the
bottom of the post.
Step 2. Use two blocks of wood,
identical in thickness, as gauge
Step 3. Tack one block near the top of the post between the plumb-bob
string and the post (gauge block 1).
Step 4. Insert the second block between the plumb-bob
string and the bottom of the post (gauge block 2).
Step 5. If the entire face of the second block makes contact
with the string, the post is plumb.
The following procedure is carried out for the entire
perimeter of the building. Inside partition walls should be
straightened the same way (Figure 6-39).
Step 1. Plumb one corner post with a level or a plumb bob.
Nail temporary braces to hold the post in place. Repeat
this procedure for all corner posts.
Step 2. Fasten a chalk line to the outside of one corner post
at the top and stretch the line to the corner post at the
opposite end of the building. Then fasten the line to this
Step 3. Place a 3/4-inch block under each end of the line for
Step 4. Place temporary braces at intervals small enough
to hold the wall straight.
Step 5. Nail the brace when the wall is far enough away from the line
to permit a 3/4-inch block to slide between the line and the plate.
Bracing is used to stiffen
framed construction and make
it rigid. Bracing may be used to
resist winds, storms, twists, or
strains. Good bracing keeps
corners square and plumb.
Bracing prevents warping,
sagging, and shifting that
could otherwise distort the
frame and cause badly fitting
doors and windows and
cracked plaster. The three
methods commonly used to
brace frame structures are letin,
cut-in, and diagonal-
sheathing bracings (Figure 6-
Let-in bracing is set into the
edges of studs, flush with the
surface. The studs are always
cut to let in the braces; the
braces are never cut. Usually 1
x 4s or 1 x 6s are used, set
diagonally from top plates to
sole plates, or between top or
sole plates and framing studs.
Cut-in bracing is toenailed
between studs. It usually
consists of 2 x 4s cut at an
angle to permit toenailing.
They are inserted in diagonal
progression between studs
running up and down from
corner posts to the sill or plates.
The strongest type of bracing is diagonal sheathing. Each board braces
the wall. If plywood sheathing 5/8 inch thick or more is used, other methods
of bracing may be omitted.
The exterior surfaces of a building usually consist of vertical, horizontal,
or diagonal sheathing and composition, sheet metal, or corrugated roofing.
However, in TOs, those materials are not always available and substitutes
must be provided. Concrete blocks, brick, stone rubble, metal, or earth
may be substituted for wood in treeless regions. In the tropics, improvised
siding and roofs can be made from bamboo and grasses. Roofing felt, sandwiched
between two layers of light wire mesh, may serve for wall and roof materials
where the climate is suitable. Refer to TMs 5-302-1 and 5-302-2 for details
on substitute, expedient, and improvised construction.The following paragraphs
cover the types of sheathing, siding, and building paper that may be used.
Sheathing is nailed directly onto the framework of the building. It
is used to strengthen the building; provide a base wall onto which the
finish siding can be nailed; act as insulation; and, in some cases, be
a base for further insulation. Some of the common types of sheathing are—
· Wood, 1 inch thick by 6, 8, 10, or 12 inches wide of No. 1
common square or matched-edge material.
· Gypsum board, 1/2 inch thick by 4 feet wide and 8 feet long.
· Fiberboard, 25/32 inch thick by 2 or 4 feet wide and 8, 9, 10,
or 12 feet long.
· Plywood, 1/4, 3/8, 1/2, or 5/8 inches thick by 4 feet wide and
8, 9, 10, or 12 feet long.
Wood. Wood wall sheathing comes in almost all widths,
lengths, and grades. However, it is normally 6 to 12 inches wide and 3/4
inch thick. Lengths are selected for economical use and the sheathing
is either square- or matched-edge. Sheathing 6 or 8 inches wide should
be nailed with two 8d nails at each stud crossing. Wider boards should
be nailed with three 8d nails. It is laid on tight, with all joints made
over the studs. It may be nailed on horizontally or diagonally (Figure
6-41); however, diagonal application adds much greater strength to the
structure. If the sheathing is to be put on horizontally, start at the
foundation and work toward the top. If it is to be put on diagonally,
start at a bottom corner of the building and work toward the opposite
Gypsum Board. This type of sheathing is made by casting
a gypsum core into a heavy, waterresistant, fibrous envelope. The long
edges of the 4 x 8 boards are tongue and grooved. Each board is 1/2 inch
thick. Gypsum board is generally used with wood siding. Gypsum board should
be nailed with 13/4- or 2-inch galvanized roofing nails spaced 7 inches
on center. Gypsum board can be nailed (together with the wood siding)
directly to the studs (Figure 6-42). Gypsum sheathing is fireproof, water
resistant, and windproof. It does not warp or absorb water and does not
require the use of building paper.
Plywood. Plywood is highly
recommended for wall sheathing
(Figure 6-42). It adds a lot more
strength to the frame than using
diagonally applied wood boards.
When this sheathing is used,
corner bracing can be omitted.
For this reason and because of
their large size, weight, and
stability, plywood panels are
faster and easier to apply.
Plywood provides a tight, draftfree
installation of high
The minimum thickness of
plywood wall sheathing should
be 1/4 inch for 16-inch stud spacing, and 3/8 inch for 24-inch stud spacing.
The panels should be installed with the face grain
parallel to the studs. A little more stiffness can be gained by installing
them across the studs, but this requires more cutting and fitting. Use
6d common nails for 1/4-, 3/8-, and 1/2-inch panels. At the edges of the
panels, space the nails not more than 6 inches on center; elsewhere, not
more than 12 inches on center.
The siding for exterior walls should be decay-resistant, hold tight
at the joints, and take and hold paint well.
Wood Siding. Wood siding should be decay-resistant,
well-seasoned lumber. It should hold tight at the joints and take and
hold paint well. It ranges from 1/2 to 3/4 inch thick by 12 inches wide.
Vertical Wood Siding. Vertical wood siding (Figure 6-43) is nailed securely
to girts with 8d or 10d nails. The cracks are covered with wood strips
called battens. To make this type of wall more weatherproof, some type
of tar paper or light roll roofing may be applied between the siding and
Horizontal Wood Siding. Horizontal wood siding (Figure
6-43) is cut to various patterns and sizes to be used as the finished
outside surface of a structure. There are two types beveled siding and
drop siding (Figure 6-43).
Beveled. Beveled siding is made with beveled boards,
thin at the top edge and thick at the butt. It is the most common form
of wood siding. It comes in 1 inch for narrow widths, and 2 inches and
over for wide types. Beveled siding is usually nailed at the butt edge,
through the top edge of the board below. Very narrow siding is quite often
nailed near its thin edge, like shingles. It is nailed to solid sheathing
over which building paper has been attached. Window and door casings are
first framed. The siding butts are put against the edges of these frames.
Corners may be mitered, or the corner boards may first be nailed to the
sheathing. Siding is then fitted against the edges.
Drop. Drop siding is used as a combination of sheathing
and siding or with separate sheathing. It comes in a wide variety of face
profiles and is either shiplapped or tongue and grooved. If used as a
combined sheathing and siding material, tongue-and-groove lumber is nailed
directly to the studs with the tongue up. When sheathing is not used,
the door and window casings are set after the siding is up. If sheathing
is first used and then building paper is added, drop siding is applied
with beveled siding, after the window and door casings are in place.
Corrugated-Metal Siding. Corrugated metal is often
used as wall cover since it requires little framing, time, and labor.
It is applied vertically and nailed to girts. Nails are placed in the
ridges. Sheathing can be used behind the iron with or without building
paper. Since tar paper used behind metal will cause the metal to rust,
a resin-sized paper should be used.
Vinyl and Aluminum Siding. Vinyl and aluminum sidings are popular, low-maintenance,
low-cost wall covering. They can be backed with polystyrene or other board
reinforcement, both to give the siding a strong base and an insulating
R factor value.
Figure 6-44, page 6-34, shows the most common vinyl and aluminum sidings
and installation accessories. Some variations exist between manufacturers,
but the basic rules for installation are universal. They are--
· Nail in the center of slots.
· Do not nail tightly, leave loose for contracting and expanding.
· Leave at least 1/4-inch clearance at all stops.
· Do not stretch tight.
· Strap and shim all uneven walls.
Step 1. Place outside and inside corners with the bottom of the trim
even with the area to weatherproof. Use a level or transit to maintain
a constant horizontal line.
Step 2. Using a level, transit, or chalk line, place the bottom of the
starter strip level with the bottom of the corner trim. The starter strip
will butt the edge of the trim.
Step 3. Snap the bottom of the siding onto the starter strip and slide
it tight into the corner trim, then out 1/4 inch to allow for expansion
and contraction of materials in changing temperatures. Nail with roofing
nails, 16 inches on center, in the center of the slot, without driving
the nails home (leaving approximately 1/16 of an inch between the nailhead
Step 4. Attach additional pieces of siding in a like manner, except
the additional pieces will be placed on top of earlier placed pieces (as
top end and bottom ends, like male and female ends in tongue-and-groove
materials). Lap tight, then pull away 1/4 inch.
NOTE: When ending a "run" into a corner
or a J-channel, cut so that installation is 1/4 inch from butt to trim.
Step 5. Install J-channels on surfaces where the siding run breaks (as
in a window or door). The J-channel provides a weatherproof surface.
On vertical breaks, butt the siding as described in the previous paragraph.
On horizontal breaks, install the undersill trim inside the J-channel.
The undersill trim is a fastening device. On surfaces such as the top
of the door or window trim, this channel will hold pieces of siding that
were cut (removing the part of siding that "snaps" onto the
top of previous pieces) tight, keeping them from flapping in the breeze.
On surfaces such as where the siding butts into the
soffit or below windows, a slotting tool is used to pierce the part of
the siding that slides into the undersill trim. This pierce pushes out
part of the siding and forms a catch. This is used when siding is pushed
into the undersill trim, providing fastening for the top of a section
of siding where nailing is not possible.
Building paper comes in several types. The most common type is resin-sized.
It is generally red or buff in color (sometimes black). It comes in rolls,
usually 36 inches wide; each roll containing 500 square feet and weighing
18 to 50 pounds. Normally, this building paper is not waterproof.
Another type is heavy paper saturated with a coal-tar product, sometimes
called sheathing paper. This type is waterproof and insulates against
heat and cold. In wood-frame buildings to be covered with siding, shingles,
or iron, building paper is used to protect against heat, cold, or dampness.
Building paper is applied horizontally from the bottom of the wall, and
nailed with roofing nails at the laps. Overlapping the paper helps water
runoff. Care must be taken not to tear the paper. The waterproof paper
is also used in the built-up roof when the roof is nearly flat. Several
layers are used, with tar between the layers.