In the context of standing seam metal roofing, single lock and double lock refer to different types of seam profiles that secure the metal panels together. Here's a breakdown of each:

Single Lock Seam

• Profile: A single lock seam involves folding one leg of the metal panel over the adjacent panel's edge, then locking it in place. This is achieved using a hand tool or a machine that crimps the seam into place.
• Installation: Generally easier and quicker to install compared to double lock seams.
• Performance: Suitable for many roofing applications, but might not offer the same level of water-tightness as double lock seams, especially in areas with high wind or heavy rain.

Double Lock Seam

• Profile: A double lock seam features two interlocking folds: the first fold locks the panels together, and the second fold creates an additional lock for enhanced strength and water resistance. This makes the seam more secure and better at keeping water out.
• Installation: More complex to install, often requiring specialized equipment and more time.
• Performance: Provides superior water-tightness and wind resistance. This type of seam is often chosen for roofs in areas with extreme weather conditions.

In summary, the choice between single lock and double lock seams depends on factors like the local climate, the building's requirements, and budget considerations. Double lock seams are generally preferred for their enhanced performance and durability.