Insulated Panel End Laps

The maximum practical length of panels for transport and handling efficiency is restricted to approximately 25 m. Where a transverse joint is required, there are two options:

  • Butt End Lap
  • Waterfall Junction

Butt End Lap

The lining and insulation are butt-jointed over the purlin, and a 150 mm overlap of the top sheet is formed in the external weather skin only, using three or more lines of sealant and fasteners. The sealant should be butyl tape, silicone or MS sealant, or self-adhesive closed cell tape according to the specifications of the manufacturer and should be positioned at the top and bottom of the lap. To provide a secure seal with flat or wide pan profiles, additional sealed rivets or stitching screws are required through the top skins only.

The challenge with this detail is that there are four layers of material to consider at the side/end junction. While successful in many instances, problems developing later are very difficult to remedy.

Waterfall Junction

A waterfall step can be achieved by putting a step in the rafter or by increasing purlin cleat heights,

The first challenge of this detail is that the cold skin of the upper sheet cannot rest on the upper surface of the lower sheet, so a thermal break must be created. The second challenge is that any gap between the upper and lower sheets must be adequately insulated to ensure that the thermal efficiency of the system is not compromised.



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