Palram SUNLIT - Manual (Page 12)

10
10
Mid-Sheet Fasteners
(Not recommended for DIY Applications)
1. A wider sheet has to be fastened to the supporting structure
by additional fastening along its width, as the connectors
on both longitudinal sides are not enough to hold the sheet
down, against the uplift force it has to withstand.
2. Fastening is usually done by screws, inserted along the
supporting internal purlins, spaced about 500mm (20in.) apart.
Figure 12
Schematic isometric view
of partial installation with
mid-sheet fasteners
3. Along the edge purlin, the fastening screws should be inserted about 300 mm (12 in.) apart.
4. A hole must be pre-drilled into each screw location. The diameter of that hole should be 2 mm larger than that of the screw, to
allow for thermal expansion movements. In case of dark colored sheets predrill even larger holes, and use wider fastener washers.
5. An electric screwdriver with an adjustable clutch should be used to tighten the screws. Avoid excess overtightening, which might
induce undue internal stresses, causing premature failure and buckling of the sheet. Pay attention to insert the screws perpendicular
to the material face, as inclined insertion could damage the sheet and/or result in leaks.
6. Use of self-tapping or self-drilling screws is recommended. In case of wooden structures, suitable wood-screws should be used.
All the screws should be corrosion resistant, with at least heavy-duty hot-dipped galvanized finish, or stainless steel (if used in an
extremely corrosive environment). The screws should be 6.35mm (1/4in.) diameter, with length according to sheet thickness, type of
washer and type of supporting structure.
7. Each screw should be fitted with a conical corrosion resistant steel washer, with specifications as the screws above or of aluminum,
at least 1mm (0.04 in.) thick, 25mm (1 in.) diameter, with a Specially Shaped integral rubber gasket, EPDM (see Palram special washer/
gasket fig. 13g). The screw should be tightened carefully, with no distortion of the washer and rubber gasket, or the flat face of the
sheet Palram will supply the suitable fasteners and washers with the SUNLITE sheets unless required otherwise.
Figure 13a
Incorrect - Overtightening
Figure 13a
Self-tapping screw
Figure 13b
Correct
Figure 13b
Self-drilling screw
Figure 13c
Incorrect - Non-perpendicular
drilling and insertion
Figure 13b
Wood screw
Figure 13g
25mm special washer/gasket
Figure 13
Typical installation screws
and obligatory washers