Reasons to use Lapseal tape
The foam tape used as a “weather strip” on top of one polycarbonate roof sheet when another is laid over it. They are typically fitted across the full width of the sheet, often with 2 strips – one approximately 50mm below the top of the bottom sheet, and the other approximately 25mm above the bottom of the overlapping sheet.
(Use PVC foam Lap seal tape if it will be in contact with metal roof sheeting.)
Reasons to use Purlin tapes
Closed cell polyethylene (PE) foam tape, with self-adhesive backing, are fitted to wooden or steel purlins to prevent noise (squeaking) caused by expansion and contraction of polycarbonate sheets during temperature variations. These tapes are used either when polycarbonate sheeting is installed between metal sheets (to allow light to penetrate to the space below), or when the entire roof uses polycarbonate roofing. Purlin tapes are normally installed along the full width of the purlin prior to placing the polycarbonate on the roof structure.
Reasons to use Back channel tapes
The foam tape is fitted into a “C-section” channel mounted on a wall, into which sheets of metal roofing are pushed in at a slight angle. This is typically used when they are fitted under a gutter in awnings and patios. The foam does not hold water, and will compress when the sheets are pushed into it, to create a watertight seal, preventing rain from blowing up the sheets and running down the wall.
(If using metal roof sheets our PVC Back channel tape should be used)