S-5-K Grip™ Snow Clamp

The answer to this question varies with the load direction, the seam profile, the roof material and the clamp model.

These variables result with a wide range of holding capacities from ±300 lbs (235 kg) to ±4,000 lbs (1800 kg). This is why for critical applications it is important to correctly identify the roof panel, seam type, gauge, etc along with the recommended seam clamp for the specific roof.  When used on some “applied cap” architectural type seam styles, S-5! may yield low load-to-failure results as compared with integrated seam profiles. Always check our load table to verify the correct allowable holding strength on your specific roof type.

We perform hundreds of rigorous tensile load tests parallel and normal to the panel seam on various gauges and profiles, the results are tabulated for your convenience here: Load Test Results. 

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Determining where to place snow retention rows is a common question. The first row is the easiest to answer, but it is really more of a question: "How much snow do you really want to fall off the roof?"

Determining where to place snow retention rows is a common question. We generally recommend that the first row be placed within 12 inches of the panel end. This recommendation is consistent with the Metal Construction Association “Metal Roof Design for Cold Climates” document has some commentary on pages 10 and 11 with respect to the first row of a snow retention system. This industry document recommends, “The first row of units or cross-members should be located close to within 12 in. of the eave end of the panels”. Read more.

Localizing snow guard systems over an entranceway or several of them rather than protecting the entire eave line of a standing seam metal roof can be done in limited cases, but extreme caution is advised. 

It is very difficult to predict how snow banks will shear when only a portion of the bank is restrained. It will not, however, shear in a straight line from the end of the snow guard system up to the ridge. Rather, it will shear in a diagonal line toward the ridge. The angle of that line becomes more acute as the slope of the metal roof increases, resulting in a large, wedge-shaped bank of snow being supported by the system -- not a small, rectangular-shaped bank. This is because the snowbank has cohesive strength within itself. The cohesive strength varies with the density and temperature of the snowbank, which always changes. Hence, the angle of shear is impossible to determine with any certainty, yet it if the correct tributary area is improperly anticipated the result may be overload and failure. Read more. 

The setscrews, which make a small dimple in the panel seam, optimizing holding strength, are normally tensioned to 115 inch-pounds for test purposes. This is because the tools normal to the trade are rated at this tightening torque. But there are some exceptions to this rule. On some profiles and gauges in steel, screw tension of 115 inch-pounds will not adequately dimple the panel seam. For this reason, some tests are run with higher screw tensions on profiles with increased gauge or thickness.

The appropriate setscrew tension is always published on installation instructions for every clamp. When the tested torque is 115 in. lbs. the recommended installation torque instructs a window between 130 to 150 in. lbs. to be sure the tested torque is reached. When test torque is higher, the corresponding window is also higher.