Formwork for Concrete Structures by R.L.Peurifoy and G.D- By EasyEngineering.net

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CHAPTER 9
Forms for Walls
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General Information
In general, forms for walls may be divided into one of three
categories:
1. Those that are built in place, using plywood for sheathing
and lumber for studs and wales
2. Prefabricated, job-built panels, using plywood sheathing,
attached semipermanently to forms made from lumber, such
as 2 × 4 or 2 × 6 S4S lumber
3. Patented form panels, using plywood facings attached to,
and backed up by, steel or wood, or a combination of steel
and wood forms ¹⁄16
For a single use, built-in-place forms are usually the most economical.
For multiple uses, where standard-size panels can be reused
without modification, it may be desirable to use either job-built or
patented-type panels. However, if there are enough reuses, patented
panels may be cheaper than job-built panels because of the longer life
and possible lower labor costs for erecting and dismantling them.
Also, because of the better dimension control in making them, patented
panels usually will give a better fit-up than job-built panels
when they are assembled into wall forms.
The common thicknesses of 4-ft-wide by 8-ft-long sheets of plywood
used for wall forms are ¾, 7 ⁄8, and 1 in. Smaller thicknesses may
be used as form liners. Thicknesses of 1 in. and 1¹⁄8 in. are available
for heavy formwork. However, the larger thicknesses make them
more difficult to handle by workers, and the cost of the thicker panels
is generally considerably higher than the small thicknesses. Special
treatment of the surfaces of the plywood will increase the life of plywood
considerably, permitting more than 200 uses per face in some
reported instances.
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