Base & Cap Load Chart and Bending Radius for Roof Purlin & Wall Girt Framing - Back to Home Page
( Bending Radius for both polycarbonate and Base & Cap )
 
Recommended Loading lbs./sq. ft. 48" wide Sheet - Also see Position & Attach Guidelines.
See Structural Load Page for further info on snow & wind load.
 
Purlin Spacing
48"
45"
42"
36"
30"
28"
Bending Radius
8mm Poly
15 lbs.
20 lbs.
25 lbs.
30 lbs.
35 lbs.
40 lbs.
8 Feet
10mm Poly
20 lbs.
25 lbs.
30 lbs.
35 lbs.
50 lbs.
60 lbs.
8 Feet
16mm Poly
30 lbs.
35 lbs.
40 lbs.
50 lbs.
65 lbs.
75 lbs.
9 Feet
25mm 6- Wall
45 lbs.
52 lbs.
60 lbs.
70 lbs.
80 lbs.
90 lbs.
15 Feet
25mm X-Wall
60 lbs.
69 lbs.
80 lbs.
93 lbs.
106 lbs.
120 lbs.
Do Not Bend
Sheet must be supported on all 4 edges, minimum of 1/2" of sheet bearing on Base or frame. When using sheets cut along width, and no longer have rib at edge, position so first rib supported by minimum of 1/2".
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Chart is poly. mfg. specs for selecting sheet thickness, rafter spacing and blocking placement to support loads on poly. Chart may be used for roof or wall design.
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Local bldg. dept. provides snow & wind load for your area. Ability to support load factor of frame strength and poly. sheet rigidity. Follow chart above and poly. sheet will support load. 
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Bending Base & Cap for arched roofs and quonsets. Limit length of arched roof to 24 ft. or use 2 sheets. Bending polycarbonate increases snow load, so purlin spacing can be further apart. Note that strong winds can lift sheets off so do not deviate to far from spacing in chart above.
B
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