Materials

MATERIALS

The primary components used in frame construction are lumber and hardware. This section includes
information on the types and sizes of lumber as well as a description of various metal fasteners.

LUMBER

Lumber varies greatly in structural characteristics. A carpenter must learn about lumber so that he can
choose the most suitable material for each job. This section covers the types, standard sizes, and uses of
lumber for construction carpentry. It also covers the methods of measuring lumber quantities in terms of
board feet, which is the unit by which it is ordered.

Grades

Lumber, as it comes from the sawmill, is divided into three main classes: yard lumber, structural material,
and factory and shop lumber. However, only yard lumber will be considered here. It is classified on the
basis of quality. The carpenter must choose a quality that is suitable for the intended purpose. At the same
time, he must exercise economy by not choosing a better (and therefore more expensive) grade than is
required. Lumber is subdivided into classifications of select lumber and common lumber.

Select Lumber

Select lumber is of good appearance and finishing. It is identified by the following grade names for comparison of quality:

· Grade A is suitable for natural finishes and is practically clear.
· Grade B is suitable for natural finishes, is of high quality, and is generally clear.
· Grade C is suitable for high-quality paint finishes.
· Grade D is suitable for paint finishes between high-finishing grades and common grades and has
somewhat the nature of both.

Common Lumber

Common lumber is suitable for general construction and utility purposes. It is identified by the following grade names for comparison of quality:

· No. 1 common is suitable for use without waste, it is sound and tight knotted, and it may be
considered watertight lumber.
· No. 2 common is less restricted in quality than No. 1, but of the same general quality. It is used for
framing, sheathing, and other structural forms where the stress or strain is not too great.
· No. 3 common permits some waste, and it is lower in quality than No. 2. It is used for such rough
work as footing, guardrails, and rough flooring.
· No. 4 common permits waste, is of low quality, and may have coarse features such as decay and
holes. It is used for sheathing, subfloors, and roof boards in the cheaper types of construction, but its
most important industrial outlet is for boxes and crates.
· No. 5 common is not produced in some kinds of lumber. It is used for boxes, crates, and dunnage, for
which the quality requirement is very low.

Uses

In frame construction, lumber is used primarily for the frame and walls.

Frames

Building frames are the wood forms constructed to support the finished members of a structure.
These include posts, girders (beams), scabs, joists, subfloors, sole plates, girts, knee braces, top plates,
and rafters. Softwoods are usually used for wood framing and all other construction carpentry covered in
this manual.

No. 2 common lumber is used for framing. Heavy frame components, such as beams and girders, are made by combining several pieces of framing material.

Walls

The exterior wall of a frame structure usually has three layers: sheathing, building paper,
and siding.

Sheathing and siding lumber are normally grade No. 2 common softwood, which is with solid
knots, no voids.

Siding is either vertically or horizontally applied. Theater construction may limit available
material to lap siding for both horizontal and vertical surfaces. For local procurement, there are
several types of drop and bevel siding, which is applied horizontally. (See page 6-32, siding.)

Sizes

Lumber is usually sawed into standard dimensions (length, width, and thickness). This allows uniformity
in planning structures and in ordering materials. Table 2-1 lists the common widths and thicknesses of
wood in rough and in dressed dimensions in the US. Standards have been established for dimension
differences between the quoted size of lumber and its standard sizes when dressed. Quoted size refers to
dimensions prior to surfacing. These dimension differences must be taken into consideration. A good
example of the dimension difference is the common 2 x 4. As shown in Table 2-1, the familiar quoted
size 2 x 4 is the rough or nominal dimension, but the actual dressed size is 1 1/2 x 3 1/2 inches. Lumber
is sawn in standard sizes used for light framing

· Thickness: 1, 2, and 4 inches.
· Width: 2, 4, 6, 8, 10, and 12 inches.
· Length: 8, 10, 12, 14, 16, 18, and 20 feet.

The actual dimensions of dressed lumber are less than the sawn dimensions because of drying and
planing (or finishing). For the relative difference between swan (standard or nominal) dimensions and
actual sizes of construction lumber, see Table 2-1.

Table 2-1. Nominal and dressed sizes of lumber

Plywood is usually 4 x 8 feet and varies from 1/8 to 1 inch in thickness.

The amount of lumber required is measured in board feet. A board foot is a unit measure representing an
area of 1 foot by 1 foot, 1 inch thick. Thus, a board that is 1 inch thick, 1 foot wide, and 1 foot long
measures 1 board foot. A board that is 1 inch thick, 1 foot wide, and 12 feet long measures 12 board feet.

To determine the number of board feet in one or more pieces of
lumber, use the following formula:

Board feet = N x T(in) x W(in) x L(ft) / 12

or

Board feet = N x T(in) x W(in) x L(in) / 144

where—
N = number of lumber pieces
T = thickness
W = width
L= length

Examples of board feet computations are shown in Figure 2-3.

HARDWARE

A wide variety of fasteners are used for frame construction in the TO. These fasteners are all made of metal. They are classified as nails, screws, bolts, driftpins, corrugated fasteners, and timber connectors.

Nails

Nails, the most common type of metal fasteners, are available in a wide range of types and sizes.

Some basic nail types are shown in Figure 2-4, page 2-6. The common nail is designed for rough framing. The box nail is used for toenailing and light work in frame construction. The casing nail is used in finished carpentry work to fasten doors and window casings and other wood trim. The finishing nail and brad are used for light, wood-trim material and are easy to drive below the surface of lumber with a nail set.

The size of a nail is measured in a unit known as a penny. Penny is abbreviated with the lowercase letter d. It indicates the length of the nail. A 6d nail is 2 inches long; a 10d nail is 3 inches long (Figure 2-5, page 2-6). These measurements apply to common, box, casing, and finish nails only. Brads and small box nails are identified by their actual length and gauge number.

A nail, whatever the type, should be at least three times as long as the thickness of the wood it is intended to hold. Two thirds of the length of the nail is driven into the other piece of wood for proper anchorage. The other one-third of the length provides the necessary anchorage of the piece being fastened. Protruding nails should be bent over to prevent damage to materials and injury to personnel.

There are a few general rules to be followed in the use of nails in building. Nails should be driven at an angle slightly toward each other to improve their holding power. You should be careful in placing nails to provide the greatest holding power. Nails driven with the grain do not hold as well as nails driven across the grain. A few nails of proper type and size,
properly placed an properly driven, will hold better than a great many driven close together. Nails are generally considered the cheapest and easiest fasteners to be applied.

Figure 2-6 shows a few of the many specialized nails. Some nails are specially
coated with zinc, cement, or resin materials. Some have threading for increased holding power. Nails are made from many materials, such as iron, steel, copper, bronze, aluminum, and stainless steel.

Annular and spiral nails are threaded for greater holding power. They are good for
fastening paneling or plywood flooring. The drywall nail is used for hanging drywall and
has a special coating to prevent rust. Roofing nails are not specified by the penny system;

they are referred to by length. They are
available in lengths from 3/4 to 2 inches
and have large heads. The double-headed
nail, or duplex-head nail, is used for
temporary construction, such as form work
or scaffolding. The double head on this nail
makes it easy to pull out when forms or
scaffolding are torn down. Nails for power
nailing come in rolls or clips for easy
loading into a nailer. They are coated for
easier driving and greater holding power.
Table 2-2 gives the general sizes and types
of nails preferred for specific applications.

Screws

Screws are more expensive than nails in both time and money, but are sometimes required for superior results. They provide more holding power than nails and can be easily tightened to draw material securely together. Screws are neater in appearance and may be withdrawn without damaging the material. The common wood screw is usually made of unhardened steel, stainless steel, aluminum, or brass. The steel may be bright-finished or blue, or it may be zinc, cadmium, or chromeplated. Wood screws are threaded for approximately 2/3 of the length of the screw from a gimlet point and have a slotted head.

Screws vary in length and size of shaft. Each length is made in a
number of shaft sizes identified by a number that shows relative
differences in the diameter of the screws. Proper screw size number
indicates the wire gauge of the body, the drill or bit size for the
body hold, and the drill or bit size for the starter hole. Table 2-3
shows screw sizes and dimensions. Table 2-4 shows applicable drill
and auger bit sizes for screws.

Both slotted and Phillips (cross-slotted) flathead and oval-head
screws are countersunk enough to allow a covering material to be
used. Slotted roundhead and Phillips roundhead screws are not
countersunk, but are driven firmly flush with the surface.

The most common types of screws, along with their uses, are
discussed in the following paragraphs.

Wood Screws. Wood screws are designated according to head
style. The most common types are flathead, oval head, and
roundhead (Figure 2-7) with either slotted or Phillips heads.
Their sizes vary from 1/4 to 6 inches. Screw sizes up to 1 inch
increase by eighths, screws from 1 to 3 inches increase by
quarters, and screws from 3 to 6 inches increase by half inches.

To prepare wood for receiving the screws (Figure 2-8), a pilot hole the diameter of the screw is bored into the piece of wood to be fastened. A smaller starter hole is then bored into the piece of wood that is to act as anchor or to hold the threads of the screws. The starter hole has a diameter less than that of the screw threads and is drilled to a depth of 1/2 or 2/3 the length of the threads to be anchored. This method assures accuracy in placing the screws, reduces the possibility of splitting the wood, and reduces the time required.

Lag Screws. The Army name for lag screws (Figure 2-9) is lag
bolt, wood-screw type. They are longer and heavier than the
common wood screw and have coarser threads, which extend
from a cone or gimlet point slightly more than half the length
of the screw. Square-head and hexagon-head lag screws are
usually placed with a wrench. They are used when ordinary
wood screws would be too short or too light and spikes would
not be strong enough. Lag screw sizes are given in Table 2-5,
page 2-10. Combined with expansion anchors, lag screws are
used to frame timbers to existing masonry.

Sheet-Metal Screws. Sheet-metal screws are used for the
assembly of metal parts. These screws are steel or brass with
four types of heads: flat, round, oval, and McAllister, as shown
in Figure 2-10, page 2-10.

Bolts

Bolts are used when great strength is required or when the
work must be disassembled frequently. Nuts are usually used
for fastening bolts. The use of washers between the nut and
wood surfaces, or between both the nut and the head and their
opposing surfaces, will avoid marring the surfaces and will
permit additional torque in tightening. Bolts are selected by
length, diameter, threads, style of head, and type.

Carriage Bolts. Carriage bolts come in three types: square
neck, finned neck, and ribbed neck, as shown in Figure 2-11.

In each type of carriage bolt, the part of the shank immediately
below the head grips the materials into which the bolt is
inserted. This keeps the bolt from turning when a nut is tightened down on it or removed. The finned
carriage bolt has two or more fins extending from the head to the shank. The ribbed type has longitudinal
ribs, splines, or serrations on all or part of a shoulder, located immediately beneath the head.

Holes bored to receive carriage bolts are bored to a tight fit for the body of the bolt and counterbored to
permit the head of the bolt to fit flush with or below the surface of the material being fastened. The bolt is
then driven into the hole with a hammer.

Carriage bolts are chiefly for wood-to-wood use, but may also be
used for wood-to-metal. If used for wood-to-metal application,
the bolt head should be fitted to the wood item. Metal surfaces
are sometimes predrilled and countersunk to allow the use of
carriage bolts for metal-to-metal fastening. Carriage bolts can be
obtained from 1/4 to 1 inch in diameter and from 3/4 to 20
inches long. (Table 2-6 lists carriage-bolt sizes.) A common flat
washer should be used between the nut and the wood surface
with carriage bolts.

Machine Bolts.
Machine bolts (or cap screws) (Figure 2-12)
are made with cut national fine or
national coarse threads. These threads
extend from twice the diameter of the bolt
plus 1/4 inch (for bolts less than 6 inches in
length) to twice the diameter of the bolt
plus 1/2 inch (for bolts over 6 inches in
length). Machine bolts are precision made and generally applied metal to metal where close tolerance is
needed. The head may be square, hexagon, double hexagon, rounded, or flat countersunk. The nut usually
corresponds in shape to the head of the bolt with which it is used. (Machine bolts are externally driven
only.)

A machine bolt is selected on the basis of head style, length,
diameter, and type of thread. The hole through which the bolt is to
pass is bored to the same diameter as the bolt. Machine bolts are
made in diameters from 1/4 to 3 inches and may be obtained in
any length desired. (Table 2-7 lists machine-bolt sizes.)

Stove Bolts. Stove bolts (Figure 2-13) are less precisely made
than machine bolts. They have either flat or round slotted heads
and have threads extending almost the full length of the body.
Stove bolts are generally used with square nuts and may be
applied metal to metal, wood to wood, or wood to metal. If
flatheaded, they are countersunk; if roundheaded, they are used
flush with the surface.

Expansion Bolts. An expansion bolt is a bolt used together with
an expansion shield (Figure 2-14), which is usually made of lead
or plastic, to provide anchorage in substances in which a
threaded fastener is useless. The shield (or expansion anchor) is
inserted in a predrilled hole and expands when the bolt is driven
into it. Wedged firmly in the hole, the shield provides a secure
base for the grip of the fastener.

The expansion shield can be used with a nail, screw, or bolt. The
shield may be obtained separately or may include the nail, screw,
or bolt.

Driftpins

Driftpins (called driftbolts for supply purposes) (Figure 2-15) are
long, heavy, threadless bolts used to hold heavy pieces of timber
together. Driftpins have heads, and they vary in diameter from
1/2 to 1 inch, and in length from 18 to 26 inches.

To use the driftpin, make a hole in the timber slightly smaller than the diameter of the pin. Drive the pin into the hole. It is held in place by the compression action of the wood.

Corrugated Fasteners

Corrugated fasteners are used to fasten joints and splices in small boards, particularly in miter joints and
butt joints. Corrugated fasteners are made of 18- to 22-gauge sheet metal with alternate ridges and
grooves; the ridges vary from 3/16 to 5/16 inch, center to center. One end is cut square; the other end is
sharpened, with beveled edges.

There are two types of corrugated fasteners: one with ridges running parallel, the other with ridges
running at a slight angle to one another (Figure 2-16). The latter type tends to compress the material,
since the ridges and grooves are closer at the top than at the bottom. Corrugated fasteners vary from 5/8
to 1 1/8 inches wide and from 1/4 to 3/4 inch long. Ridges on the fasteners range from three to six ridges
per fastener.

Corrugated fasteners are a great advantage when used to fasten parallel boards together (as in fastening
tabletops), to make any type of joint, and to substitute for nails
where nails may split the lumber. The fasteners have a greater
holding power in small lumber than nails do. The proper method
of using the fasteners is shown in Figure 2-17.

Timber Connectors

Timber connectors are metal devices for increasing the joint
strength in timber structures. Efficient connections for either timber-to-timber joints or timber-to-steel
joints are provided by the several types of timber connectors. The right type is determined by the kind of
joint to be made and the load to be carried. The connectors--

· Eliminate much of the complicated framing of joints.
· Simplify the design of heavy construction.
· Provide greater efficiency in the use of material.
· Reduce the amount of timber and hardware used.
· Save time and labor.

Split rings (Figure 2- 18) are made of lowcarbon steel and have 21/2- and Winch diameters. Split rings are used
between two timber faces for heavy construction. They fit into grooves that are cut half the depth of the ring into each of the timber faces. The grooves are made with a special bit used in an electric, air, or hand drill. The tongueand- groove split in the ring permits the ring to bear equally against the cone wall and the outer wall of the groove into which it is placed. The inside bevel and mill edge make installation into, and removal from, the groove easier.

Toothed rings (Figure 2-19) are corrugated and toothed and are made from 16-gauge plate, low-carbon
steel. They are used between two timber frames for comparatively light construction and are embedded
into the contact faces of the joint members by pressure.