Home arrow Phoenix Advantage arrow Fully Locked Seams


Fully Locked Seams

When installing a standing seam roof, we fully double-lock our seams. The seam structure is a very old design, dating back many centuries. The advent of the roll-forming machine has made standing seam roofing very popular in recent years. This machine allows roofers to form a panel to the full rafter length of the building, rather than being constrained by the length of a shop brake, where panels were traditionally fabricated until the late twentieth century.

Presently, a new, modern mindset has sprung up in which contractors only perform the initial lock of the seam. This single-lock is the first stage of double-locking, and is only half of the process. For the contractor, this is the easiest and least costly method of standing seam installation. Unfortunately, those who do not double-lock the seams are not providing the best roof for the customer.

Double-locking the seams requires the initial investment in a seaming tool (quite costly), and requires the added time of double-locking the seams with the seaming tool. A double-locked seam is more rigid, secure, and watertight.


One of our seaming tools in action on a copper roof:















Below is a detail of the seam-locking process.


Step #1:  The first panel is placed and fastened to the roof. The second panel is then placed on the roof, with the seams interlocking as shown below:





















Step #2:  A hand tool is then used to 'single lock' the seams together, as illustrated below:




















Step #3:  After this, the electric seaming tool is used to fully 'double lock' the seam, to complete the standing seam application:




















As mentioned above, some companies do not fully lock their seams, as shown above; but stop at step #2. One can see how this would be faster, easier, and less costly for the contractor. At the same time, stopping at step #2 does not provide you, the customer, with the best standing seam roof, but a roof that is unfinished. It is clear that fully locking the seams is the best way to craft a standing seam roof.

Another reason some roofers do not fully double-lock the standing seam is that they install the ridgecap first (please see details in the ridgecap article). Once the metal panel is pushed under an existing ridgecap, a seaming tool can no longer be used to double-lock the seam. If the contractor were to double-lock the seam, the top portion would need to be completed by hand, a time consuming, frustrating, and damaging process.