Palram SUNLIT - Manual (Page 10)

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4. “Roofing & Cladding” Installation Method
This is a simpler, more practical method, resembling the one used for single-wall, corrugated plastic (or metal) sheets. It employs
longer strips, with wider dimension. Length is as long as possible without excess deformation by thermal expansion. SUNLITE sheets
are laid on top of the purlins, with rib channels directed down the slope, perpendicular to the
purlins. Span between purlins is determined by the load and deflection characteristics
of the specific SUNLITE sheet.
1. The sheets are connected to each other by long connecting elements.
2. The wide variety of these connection methods falls into two main
categories: “wet” or “dry” installation systems. The connecting elements
(made of aluminum, sheet metal or plastic- rigid PVC or polycarbonate) are
designed as connectors, not as load supporting members. They connect the
sheets to each other, achieving one unified watertight exterior shell. Additional
strength and rigidity achieved through them is an added bonus.
Basic inverted “H” polycarbonate connecting profile
An old and simple form enabling a lengthwise (side by side) connection between twin/multi-wall sheets. It
is sometime offered with a specific size profile for each sheet thickness, or in versatile, more flexible design enabling the use of one
profile with 2 consecutive thicknesses (4-6 & 8-10 “H” profiles). This connecting method is practically inappropriate for the thicker
SUNLITE panels.
1. “Dry” method: The edges on both sides are inserted into the profile, holding
the sheets by “dry” mechanical friction, with the sheets on both sides fastened
to the structure, along the purlins, by fixing screws, about 500-600 mm (20-24
inches) apart.
2. “Wet” method: both the profile channels are half-filled with silicone, which
acts, after installation and curing, both as sealer and adhesive. It may offer better weatherproofing at shallower slopes, than the “dry”
system, but is very difficult to install properly and cleanly (Figure 7).
Notes:
1. The connector itself is not fixed to the purlins.
2. Both systems are basic and disclose several shortcomings: difficult and bothersome installation, plain looks, weak and imperfect
connection and sealing. Installation may prove to be lengthy and messy for inexperienced hands. They are, however, considered the
cheapest.
Two-part polycarbonate connecting profile, which is made of the following:
1. A lower base profile, usually the more rigid of the two, on which the edges of the adjoining sheets are placed. Usually the base
profile is fastened to the purlins by screws through the middle, with both edges free, letting the sheets slide easily due to the thermal
expansion and contraction process.
2. The upper part, usually more flexible than the base, clips on the base profile by hand pressure, holding both sides of the adjoining
sheets in place by mechanical pressure.
This type is easier to install, more reliable in holding the sheets and sealing the connection. It is used, mostly, in “dry” installation, but
could be assisted by silicone on the upper and lower profile. “Wet” installation like this is difficult to keep clean during installation and
with long sheets may lose its effectiveness due to excessive expansion.
Figure 6
Figure 7
Basic, inverted H polycarbonate connecting profile
Figure 8
Drawing of typical two-part polycarbonate connecting profiles currently used
Figure 8a Figure 8b Figure 8c