PART B: SELECT MATERIALS FOR WALL FORMS
4. Selecting the materials for wall forms is the first step in the process of designing a concrete
wall. The remaining steps are covered in Part C of this subcourse.
Step 1. Select the appropriate materials for the wall form. To do this, you will need to
understand what materials are available and which to use. Materials and sizes to select from
are as follows:
Sheathing. Sheathing forms the vertical surfaces of a concrete wall. The materials
used for sheathing are normally 1- x 4- or 1- x 6-inch boards or 5/8- or 3/4-inch
plywood. The type of sheathing selected will depend upon the type available at the
supply point or on the materials-available list.
Sheathing can be 1 1/4-, 1 1/2-, or 2-inch-thick boards of any width; however,
these sizes are used only on extra-large forms, such as seawalls or dams.
Sheathing should be made of plywood whenever possible because plywood
can cover large areas with a single sheet The ease of erection, economy, and
strength are also reasons for selecting plywood. If available, 1/2- or 1-inch
plywood may also be used.
Studs add vertical rigidity
to wall forms.
Studs are made
of 2- x 4-inch
material; however, they are also available in sizes of 4 x 4 or 2 x 6 inches. For
economical reasons, use 2- x 4-inch material if possible. The larger the material, the
greater the load on the studs.
Wales. Wales reinforce the studs when the studs extend upward more than 4 or 5 feet.
Wales are structured of the same materials as studs. Usually, 2 x 4s are used because
they are the most economical. However, wales may also be made of 4 x 4s or 2 x 6s.
Always nail wales together to make them doubled, thereby increasing their strength.
The exception to nailing wales together is to substitute a heavier material, such as a
single 4 x 4 for two 2 x 4s.
Bracing. Braces help stabilize wall forms. To prevent movement and maintain
alignment, forms are normally braced with 2- x 4-inch material. Bracing may also be
made of 4- x 4- or 2- x 6-inch materials. The choice would depend upon the size of
the form and the type of material available.
Tie wires. Tie wires secure the formwork against the lateral pressure of the plastic
concrete. Tie wires always have double strands. Tie wires are normally made of
number (No.) 8 or 9 gage annealed (soft) wire, but larger wire or barbwire may also
be used. The larger the wire gage number, the smaller the diameter of the wire. Since
barbwire is doubled, a smaller gage wire can be used.