Basic Details:
Additional Loose Lock Seams

Additional Loose Lock Seams

Transverse Seams: Transverse seams are often used on copper standing seam and batten seam roofs. See specific roof type for requirements.

Narrow Loose Lock - Transverse Seam, Steep Pitch: This variation is limited to roof slopes of at least 6" per foot. The upper edge of the lower sheet is folded over 2". Cleats may be used at transverse seams to facilitate installation and limit movement. The lower edge of the upper sheet is then folded under ¾" and locked into the lower sheet.

Wide Loose - Lock - Transverse Seam, Low Pinch: This seam reduces the chance of water penetration through wind action and is recommended for slopes 3" to 6" per foot. Here, the lower sheet is folded over and lapped at least 4" by the upper sheet. Cleats may be used at transverse seams to facilitate installation and limit movement. An additional copper locking strip is soldered onto the lower sheet, into which the upper sheet is locked.

Standing Seam: This is a typical standing seam. The copper sheets are bent up where they meet. One sheet extends 1/8" higher than the other. This extension is folded over the end of the shorter sheet. The two sheets are then folded over together. Cleats, 12" O.C. along the seam, are folded in together with the copper sheets.

On flat surfaces the finished seam may be almost any height, but should be at least 1" with a ½" lock. Seam heights of 2" or more suffer in appearance and are not recommended. On curved surfaces, such as domes and barrel arches, seams may be ½" to ¾" high, in order to facilitate installation. Transverse seams should be avoided in areas where the curved surface results in slopes less than 3" per foot.

Single Lock Standing Seam: This is the simplest form of a standing seam. The copper sheets are bent up where they meet. One sheet extends up 1" beyond the other. This longer upstand is then folded down over the other. This seam is not recommended in high wind areas.

Batten Seam: This typical batten seam shows a square batten. The expansion space is provided by folding the copper sheets up 1/16" short of the batten. An alternative method is to use tapered battens, that are 1/16" narrower on each side at the bottom than at the top. This second approach allows the upstanding legs of the copper pans to be vertical. Transverse seams should be avoided in areas with slopes less than 3" per foot.

Pre-fabricated Standing Seam: This detail shows a typical standing seam that is part of a pre-fabricated roofing system. Its properties are similar to the Snap Lock Standing Seam discussed below. These systems vary with manufacturer and are proprietary. For additional information and specific system performance consult the respective manufacturer's literature.

Standing Seam with Snap Lock: This is another variation of the typical standing seam, most often used in prefabricated standing seam roofing systems.

The edge with the lock is cleated to the deck. The adjacent pan is pressed over the lock until it snaps securely. Sealant may be applied, either at the shop or in the field, for low pitch conditions, consult manufacturer. This type of system does not usually require additional finishing such as button punching or field seaming.

Drive Cleat or Lock: This method of joining separate sheets of copper is similar to the common lock, except that it uses an intermediate copper strip. This seam can act as an expansion relief, such as in parapet caps.

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