form reuse. Some of the elements
wooden forms are sheathing, studs,
shoe plates, spreaders, and tie wires.
that make up
CONSTRUCTION. Sheathing forms the
surfaces of the concrete. It should be as smooth as
possible, especially if the finished surfaces are to be
exposed. Since the concrete is in a plastic state when
placed in the form, the sheathing should be watertight.
Tongue-and-groove sheathing gives a smooth,
watertight surface. Plywood or hardboard can also be
used and is the most widely accepted construction
The weight of the plastic concrete causes
sheathing to bulge if it is not reinforced. As a result,
studs are run vertically to add rigidity to the wall
form. Studs are generally made from 2-by-4 or
Studs also require reinforcing when they extend
over 4 or 5 feet.
This reinforcing is supplied by
Double wales also serve to tie
prefabricated panels together and keep them in a
straight line. They run horizontally and are lapped at
the corners of the forms to add rigidty. Wales are
usually made of the same material as the studs.
The shoe plate is nailed into the foundation or
footing. It is carefully placed to maintain the correct
wall dimension and alignment. The studs are tied into
the shoe and spaced according to the correct design.
Small pieces of wood are cut the same length as
the thickness of the wall and are placed between the
forms to maintain proper distance between forms.
These pieces are known as spreaders. The spreaders
are not nailed but are held in place by friction and
must be removed before the concrete covers them. A
wire should be securely attached to each spreader so
that the spreaders can be pulled out after the concrete
has exerted enough pressure on the walls to allow
them to be easily removed.
lie wire is designed to hold the forms securely
against the lateral pressure of unhardened concrete. A
double strand of tie wire is always used.
BRACING. Many types of braces can be used
to add stability and bracing to the forms. The most
common type is a diagonal member and horizontal
member nailed to a stake and to a stud or wale, as
shown in figure 7-8. The diagonal member should
make a 30° angle with the horizontal member.
Additional bracing may be added to the form by
placing vertical members (strongbacks) behind the
wiles or by placing vertical members in the corner
formed by intersecting wales. Braces are not part of
the form design and are not considered as providing
any additional strength.
REINFORCEMENT. Wall forms are usually
reinforced against displacement by the use of ties.
Two types of simple wire ties, used with wood
spreaders, are shown in figure 7-9. The wire is passed
around the studs, the wales, and through small holes
bored in the sheathing. Each spreader is placed as
close as possible to the studs, and the tie is set taut by
the wedge, as shown in view A of figure 7-9, or by
twisting with a small toggle, as shown in view B. As
the concrete reaches the level of each spreader, the
spreader is knocked out and removed. Figure 7-10
shows you an easy way to remove the spreaders by
drilling holes and placing a wire through them. The
parts of the wire that are inside the forms remain in
the concrete; the outside surplus is cut off after the
forms are removed.
Figure 7-9.-Wire ties for wall forms.