Snap-Lock Standing Seam

Snap-lock (also written snap-on or SnapLock) panels are roll-formed with seam edges shaped so that one panel's female leg snaps over the next panel's male leg by hand pressure or a light tap. No seaming machine is needed, which speeds installation and makes snap-lock a common choice for residential and light commercial roofs.

Attachment methods

Two broad variants exist:

• Clip-fastened snap-lock: separate concealed clips are screwed to the deck and engaged in the seam before the next panel snaps on; they grip the seam while letting the panel expand and contract, which suits long panels and aluminium.
• Nail-strip (fastening flange) snap-lock: the panel has a slotted flange along one edge that is screwed directly to the deck and is then hidden by the next panel. This is simple but restricts thermal movement more than sliding clips, so panel lengths are usually limited.

Strengths

• Fast installation with basic tools.
• Concealed fasteners keep the weathering surface unpierced.
• Panels can be removed and replaced more easily than mechanically seamed panels.

Limitations

• Seams are not folded, so they generally have lower uplift resistance and are less suited to very low slopes or areas where water or snow can stand against the seam than double-lock mechanically seamed systems.
• As with all standing seam roofs, panels pinned so they cannot move can develop visible waviness and noise.

Performance testing

Snap-lock systems are tested like other panels. Some coated steel snap-lock products are listed for UL 2218 Class 4 impact resistance and for wind uplift under standards such as UL 580 or ASTM E1592.