Palram SUNLIT - Manual (Page 13)

SUNLITE® Technical Guide
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8. Screw buttons: Improved performance can be obtained by replacing the
washers with special plastic screw buttons, fitted with a suitable rubber gasket,
with or without a closing cap. They fit the thickness of each type of sheet (6, 8,
10, 16 mm, and possibly 25 mm), differing by sleeve length. Their advantage:
the sleeve prevents excessive tightening and local squashing around the
screw, and is softer on the sheet, reducing risk of tear or shear around the
screw’s stem. They also offer a seal between the fastener hole and the open
channels of the sheet, preventing possible infiltration of water and dirt into
the internal space of the sheet. Screw buttons can suit the 6.35mm (1/4 in.)
screws mentioned above, although it is recommended to use slightly longer
screws to accommodate the button thickness.
Palram recommends perforating SUNLITE for fastening as little as possible, and
prefers the use of clamped edge installation. Palram recommends that the
use of fastening screws in a glazing system, even with plastic buttons, should
be limited to economical, price conscious projects only. Two or four-sided
clamped glazing is a preferred choice.
Design spans between Supporting Purlins
According to Designated Loads for the Roofing and Cladding Method
Max. Recommended Spans between Support Purlins - Flat / Slightly Curved Roofing/Glazing
Structure
Thickness
Distance (center-to-center) between supporting purlins - according to wind/Snow loads below
50 Kg/m² 10 psf 80 Kg/m² 16 psf 100 Kg/m² 20 psf 120 Kg/m² 25 psf
mm mm Inch mm Inch mm Inch mm Inch
Twin Wall
6 900 36 800 32 650 26 500 20
8 1150 46 1000 40 850 34 650 26
10 1250 50 1150 46 1050 42 900 36
Triple Wall
8 1120 44 970 38 820 32 620 25
10 1220 48 1125 45 1020 41 870 35
16 1600 64 1450 58 1250 50 1130 45
X-Lite
16 1650 65 1500 59 1300 51 1180 46
25 1850 74 1700 68 1550 62 1425 56
32 2050 82 1900 76 1750 69 1600 63
35 2075 82 1925 76 1775 70 1625 64
Notes:
1. Span calculation is based on general professional know-how, previous experience & specialized expertise with this type of products.
2. Spans depicted are drawn from loading tests and extrapolations based on L/20 deflection (5%) at the specific span and load using continuous multi-span
supports. The values refer to mid-spans. Edge-spans (lower & upper ends) should be approx. 20% smaller.
3. SUNLITE panels can withstand higher loads and/or wider spans without failure. However the involved deflections will exceed L/10 (10%) of the span, which is
unacceptable in most cases.
Curving SUNLITE sheets gives them higher strength and rigidity, as in the case of two-sides clamping described in the next page.
>2 mm more than
diameter of button stem
Rubber gasket
Plastic button
Fastening screw
Optional cover
>30 mm
Figure 14