What is a mechanical lock roof system?

Mechanical lock roofs are standing seam roof systems that utilize concealed fasteners. The main identifier of a mechanical seam system is that the panel profiles are folded into one another as opposed to just overlapping. The folding of the metal profiles promotes a more watertight seam than their snap-lock counterpart. Mechanical seams are commonly seen standing 1” or 1.5” in height, but in certain areas or on certain projects (commercial) 2” high seams are necessary.

Common Manufacturer Mechanical Lock Systems Panel Names 

Although panel manufacturers or coil suppliers offer the same mechanical lock systems, they may refer to them by their own names. Here are common ones


Single Lock or Double Lock?

Mechanical standing seam profiles are most commonly seen looking like the profile below

Notice that the edges are formed into male and female profiles. These male and female profiles are designed to nest into one another and then are seamed using a crimping tool. A single lock seam, as pictured below, stands up and bent at 90° when locked together (upside down “L”). The single lock seam is suitable for mild climates with less wind and precipitation. One advantage single lock seams have is that they are more easily pulled apart for repair if the roof is damaged.

More often than not, mechanical seams are folded once again into double lock seams. There are many advantages of double locking your seams.

  • Low slope or steep slope applications: 2/12 minimum ; even .5/12 is some cases when continuous in-seam sealant is applied
  • Weather Tough: The double lock system is ideal for extreme weather conditions and resists strong winds and heavy wind-driven rain. 
  • Historically accurate: Mech. lock is generally regarded as aesthetically appealing. You will commonly see 1” mechanical seams in copper.  The double lock system has been used for centuries around the world and has stood the test of time. The slim profile of the seam is visually appealing for residential applications
  • Versatility: Mechanical seams do not need to rely heavily on “Z” closures and sealant. There are a variety of European folding details that give the roofer skilled options to show off their abilities and create value for their customers.

Intimidation Factor:

Since the advent of snap lock standing seam roofs systems, mechanical lock standing seam has been overtaken as the primary metal standing seam system. The main reason being the speed of the snap lock installation vs the mechanical. Some newer metal roofers may find mechanical seams too labor intensive, or do not understand the seaming options available.

How Stortz Is Helping

At Stortz Tools, we carefully select the most effective and quality roofing tools from around the world. In regards to mechanical lock seaming, we have added some products to our line that are making mechanical lock a more attractive option for installers.  This means:

Faster onsite panel creation: 

    • Unlike Snap lock roofing, a roofer can make a mechanical lock panel on a jobsite without a pan forming machine. This is extremely beneficial if you are short a panel, or have a panel damaged. Also, this is handy for tapered panel creation. Here are two tools that we carry to fabricate mechanical locking panels. In theory, you could hand form every panel on your entire mechanical lock roof using these hand tools. In practice, it is faster and less laborious to have a pan forming machine do the work.

Simple Seaming tools

    • Many metal roofers are not clear on what tools they need to complete the seaming of the mechanical panels. Stortz tools sells seaming hand tool and seaming machines for all sizes of mechanical lock. Since the advent of drill powered seamers, seaming has become less cumbersome to the roofer. No longer do you need to carry around a 50+lb machine for smaller projects. Just a hand tool and a drill seamer, and you can zip up your 1” or 1.5” mechanical lock seams.

Hand Crimpers that protect your panel

    • We carry hand tools for seaming your panel AND protecting your panels painted surface. The Biegetec 2in1 seamer combines both locking stages in one tool as well as keeps from scratching paint. This tool is an amazing addition to a mechanical roof jobsite.