5/8-inch-thick sheets perform better because of their
greater thickness and strength.
Standard siding sheets are 4 by 8 feet; larger sizes
are available. They must be applied vertically with
intermediate and perimeter nailing to provide the
desired rigidity. Most other methods of applying sheet
materials require some type of sheathing beneath.
Where horizontal joints are necessary, they should be
protected by simple flashing.
An exterior-grade plywood should always be used
for siding and can be obtained in grooved, brushed, and
saw-textured surfaces. These surfaces are usually
finished with stain. If shiplap or matched edges are not
provided, the joints should be waterproofed. Water-
proofing often consists of caulking and a batten at each
joint and a batten at each stud if closer spacing is desired
for appearance. An edge treatment of water-repellent
preservative will also aid in reducing moisture
penetration. When plywood is being installed in sheet
form, allow a 1/16-inch edge and end spacing.
Exterior-grade particle board might also be
considered for panel siding. Normally, a 5/8-inch
thickness is required for 16-inch stud spacing and
3/4-inch thickness for 24-inch stud spacing. The finish
must be an approved paint, and the stud wall behind
must have corner bracing.
Medium-density fiberboards might also be used in
some areas as exterior coverings over certain types of
sheathing. Many of these sheet materials resist the
passage of water vapor. Hence, when they are used, it is
important that a good vapor barrier, well insulated, be
used on the warm side of the insulated walls.
Nonwood materials are used in some types of
architectural design. Stucco or a cement-plaster finish,
preferably over a wire mesh base, is common in the
Southwest and the West Coast areas. Masonry veneers
can be used effectively with wood siding in various
finishes to enhance the beauty of both materials.
Some structures require an exterior covering with
minimum maintenance. Although nonwood materials
are often chosen for this reason, the paint industry is
providing comparable long-life coatings for wood-base
materials. Plastic films on wood siding and plywood are
also promising because little or no refinishing is
necessary for the life of the building.
Siding can be installed only after the window and
doorframes are installed. In order to present a uniform
appearance, the siding must line up properly with the
drip caps and the bottom of the window and door sills.
At the same time, it must lineup at the corners. Siding
must be properly lapped to increase wind resistance and
watertightness. In addition, it must be installed with the
proper nails and in the correct nailing sequence.
One of the most important factors in the successful
performance of various siding materials is the type of
fasteners used. Nails are the most common, and it is poor
economy to use them sparingly. Galvanized, aluminum,
and stainless steel corrosive-resistant nails may cost
more, but their use will ensure spot-free siding under
adverse conditions. Ordinary steel-wire nails should not
be used to attach siding since they tend to rust in a short
time and stain the face of the siding. In some cases, the
small-head rails will show rust spots through the putty
and paint. Noncorrosive nails that will not cause rust are
Two types of nails are commonly used with siding:
the small-head finishing nail and the moderate-size
flathead siding roil.
The small-head finishing nail is set (driven with a
nail set) about 1/16 inch below the face of the siding,
The hole is filled with putty after the prime coat of paint
has been applied. The more commonly used flathead
siding nail is nailed flush with the face of the siding and
the head later covered with paint.
If the siding is to be natural finished with a
water-repellent preservative or stain, it should be
fastened with stainless steel or aluminum nails. In some
types of prefinished sidings, nails with color-matched
heads are supplied.
Nails with modified shanks are available. These
include the annularly (ring) threaded shank nail and the
spirally threaded shank nail. Both have greater
withdrawal resistance than the smooth-shank nail, and,
for this reason, a shorter nail is often used.
In siding, exposed nails should be driven flush with
the surface of the wood Overdriving may not only show
the hammer mark, but may also cause objectionable
splitting and crushing of the wood. In sidings with
prefinished surfaces or overlays, the nails should
driven so as not to damage the finished surface.