A Mechanical Roof Seamer and its Performance

Wikipedia defines a mechanical roof seamer as “a portable rollforming machine that is used to install mechanically seamed structural standing seam metal roof panels, as part of an overall metal construction building envelope system.The machine is small and portable to be handled by an operator on top of a roof. The machine is applied to the overlapping area when two parallel roof panels meet. The action of the machine bends the two panels together to form a joint that has weathertight qualities superior to other types of roof systems and cladding.”

Specialized, calibrated and changeable to obtain hundreds of finished seam results

By Kevin Thomas

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Wikipedia’s definition, while accurate, portrays a simplistic view of a complex process performed by an extremely robust machine. Precisely bending multiple layers of 22-gauge or thicker steel is no simple task. The chassis of a roof seamer is designed to house usually three, four or five “stations” that when engaged, perform the bending process as the seamer moves along the panel seam. The chassis also houses an electric motor and gearing system specifically engineered to provide the necessary torque and speed to produce a perfect seam. Roof seamers are specialized and calibrated specifically to panel profile specifications. By changing the combination of forming roller profiles and positions, it is possible to obtain literally hundreds of finished seam results.

Seamer Considerations

Although some installers choose to purchase their own roof seaming machines, it is often more advantageous to rent them from a reputable provider. In this way, the installer can forgo a large capital investment while being assured that the machine is properly serviced and calibrated at all times. There are a multitude of variables that must be understood prior to ordering a rental seamer.

The final seam profile required for the roof is stipulated by an engineer or an architect during the design stage based on such things as project location, wind loads, snow loads and other factors.

The seamer provider will need to understand the finished seam profile:

• Is the finished seam a 90-degree (Single/Triple Lock) or a 180 (360)-degree (Double/Quad Lock) seam?

• Is the panel material painted or Galvalume steel, or is it aluminum, zinc or copper?

• What is the thickness or gauge of the material?

• What is the roof’s pitch or slope?

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A reputable seamer provider will be able toaccommodate these variables through the set-up of the seamer prior to shipping. In many cases, panel manufacturers have partnered with a reputable seamer provider making their seamer proprietary for use on their panels.

Prior to the signing of this type of partnership, many hours of testing have been completed to ensure the seamer will provide a finished seam to meet the manufacturers’ specifications. A close relationship between the seamer provider and the panel manufacturer is a very important aspect in assuring a successfully seamed roof. Panel manufacturers must keep the seamer provider abreast of any enhancements to their panel design or function. A reputable seamer provider should continuously be engineering improvements into their seamer design to better serve the customer.

Hand Seaming/Panel Installation

Proper hand crimping prior to engaging the roof seamer is crucial to ensure the roof seamer will perform as it should. A 90-degree starter hand crimp should be approximately 16 inches in most cases. If the finished seam profile calls for a full 180-degree seam, an additional, approximate 4-inch,180-degree crimp must be applied by a 180-degree hand crimper before the seamer is locked onto the panel to begin operation. Hand crimpers, like roof seamers, are specialized and calibrated to operate on specific panels. It is very important to understand correct hand crimping procedures prior to running the roof seamer.

Proper installation of roof panels, according to the panel manufacturer’s installation instructions, is equally important to the roof seamers performance. Out-of-modulation panels will hamper or, depending on the severity, not allow the roof seamer to function properly. Debris such as dirt, mud, sand or salt should be removed from the panels before the roof seamer is operated. Panel finishes can be damaged by debris being picked up by the roof seamers rollers.


On-site preventative maintenance is recommended and should be performed by the contractor. When seaming is completed each day, the roof seamer should be inspected, cleaned, dried and lubricated per instructions from the seamer provider. It then should be stored in its container until the next time it is used. Daily inspection and maintenance are critical to ensure the roof seamer will perform as designed until the entire roof is seamed.

Kevin Thomas is a senior service representative for D.I. Roof Seamers | Developmental Industries Inc., Corinth, Miss. For more information, visit

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