1. If you have already built your structure with support rafters or wall joist on even centers (i.e. 2', 4', etc) and are using "H" channel, you will have to trim each polycarbonate sheet by approximately 1-1/2". This is because the stock width of the sheet is either a standard 4' or 6' wide. "H" channel has a rib that separates the two sides of the channel. The rib is about 1/2" to 1" wide depending on whether you use standard or snap "H" channel. Before you cut, be sure to measure the distance between each location of "H" channel for correct distance.
Other options to cutting the twinwall include (A) using perlins horizontally across your rafters or joists, fasting "H" channel perpendicular to perlins. (B) Design your greenhouse with rafters or joists spacing wide enough for full standard twinwall width. (3) cap the joints between twinwall sheets with a 1 x 4, using silicone caulk under each edge of the 1 x 4 and a screw through center.
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2. Always install the sheets with the flutes oriented vertically, When used as a roof covering, design with at least a
minimum 5 to 10 degree slope, never level.
3. Remember to allow for expansion and contraction in every installation. Bronze and grey panels change more in size. Use extrusions that allow for sufficient edge engagement plus the expansion allowance. Usually, a pre drilled hole approximately 1 size larger than the screw you were using is enough.
4. Panels can be cut with protective masking in place with a fine tooth saw or sharp knife. Remember to remove the masking prior to final fixing in place. Chips from cutting should be blown out of the flutes.
5. The specially treated weather side is identified on the masking. This side must always face the exterior.
6. In vertical Installations, the top flutes should be capped with an extrusion or tape and the bottom capped or tapped per specifications for drainage.
7. Note for 16mm "H" channel: If you want to use "H" channel for joining 16 mm triplewall you must use the "Snap" Profile style. This is a tight fit for 16 mm and more than likely will require that you hold the snap in place with screws through the center of the profile. Apply silicone caulk where the top piece of the "H" channel meets the triplewall before you attach the top piece of the "H" channel.