The Formula for Bending Sheet Metal Into Z-Flashing (2 Sizes) on a Tapco Brake


The secret to step-bends, aka Z-flashing, that are smaller than 3/4-inch

The typical offset on sheet metal brakes is 3/4-inch, so bending a 3/4-inch step Z-flashing is quick and easy. But bending a smaller step for a Z-flashing is trickier. This video demonstrates the formula for bending sheet metal around the standard width.

The formula for bending sheet metal with a 3/4-inch step

  • Step 1: Bend 90-degrees
  • Step 2: Flip the sheet metal over and bend another 90-degree bend

The default offset between the bending edge and the clamping hinge is 3/4-inch, so a 3/4-inch Z-flashing is very simple to make. This is handy because a lot of exterior trim is 3/4-inch thick. 

The formula for bending sheet metal with a 1/2-inch step

Because the default offset between the bending edge and the clamping hinge is 3/4-inch, many people do not know that you can smaller Z-flashing sizes. In fact, you can make 1/2-inch Z-flashing or even 3/8-inch Z-flashing by splitting the first 90-degree bend into two parts.

  • Make a 45-degree bend
  • Flip over sheet metal, make the second 90-degree bend
  • Flip over the sheet metal again and finish the 45-degree bend into a 90-degree bend

Step-bends are an integral part of many profiles needed for roofing and siding installation and replacement. Now you know that you have more formulas for bending sheet metal


—This video is from Tapco Tools, one of ProTradeCraft's advertisers. Serving professional siding applicators since 1961, Tapco brakes and accessories bring measuring, mobility, decorative designs, and strengthening ribs to fascia, window trims, frieze boards, porch posts, and beams. See all of Tapco's content here.


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