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

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Forms for Walls 231
Plywood
Thickness,
in.
¹ 5 ⁄32 2,715
(2,715)
½ 2,945
(2,945)
¹ 9 ⁄32 3,110
(3,110)
5
⁄8 3,270
(3,270)
23
⁄32 4,010
Support Spacing, in.
4 8 12 16 20 24 32
(4,010)
¾ 4,110
(4,110)
1 1 ⁄8 5,965
(5,965)
885
(885)
970
(970)
1,195
(1,195)
1,260
(1,260)
1,540
(1,540)
1,580
(1,580)
2,295
(2,295)
355
(395)
405
(430)
540
(540)
575
(575)
695
(695)
730
(730)
1,370
(1,370)
150
(200)
175
(230)
245
(305)
265
(325)
345
(325)
370
(410)
740
(770)
—
115
100
(135)
145
(190)
160
(210)
210
(270)
225
(285)
—
—
—
—
—
(100)
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485
(535)
—
(100)
110
(145)
120
(160)
275
(340)
—
—
—
—
—
—
—
—
—
—
—
—
130
(170)
Notes:
1. Courtesy APA—The Engineered Wood Association, “Concrete Forming,” 2004.
2. Deflection limited to l/360th of the span, l/270th for values in parentheses.
3. Plywood continuous across two or more spans.
TABLE 9-7 Recommended Maximum Pressure on Plyform Class I—Values in
Pounds per Square Foot with Face Grain Across Supports
Calculating the Allowable Concrete Pressure on Plyform
When computing the allowable pressure of concrete on plywood or
Plyform, the center-to-center distances between supports should be
used to determine the pressure based on the allowable bending stress
in the fibers.
When computing the allowable pressure of concrete on plywood
or Plyform as limited by the permissible deflection of the plywood, it
is proper to use the clear span between the supports plus ¼ in. for
supports whose nominal thicknesses are 2 in., and the clear span
between the supports plus 5 ⁄8 in. for the supports whose nominal
thicknesses are 4 in.
The recommended concrete pressures are influenced by the
number of continuous spans. For face grain across supports, assume
three continuous spans up to 32-in. support spacing and two spans
for greater spacing. For face grain parallel to supports, assume three
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