How to Flash Window Jambs with ZIP System Flashing Tape

February 1, 2019


Stop air and water leaks at the side of windows by sealing the flange to the sheathing

After installing the sill pan, it's time to install the window and flash the jambs. Next, we'll seal the window head flange with ZIP System® flashing tape


Step by step:

  • Place shims in each corner of the window sill.
  • Caulk along the nail pattern of the window using an exterior grade sealant. ZIP System reccommends: butyl, 100% silicone, or polyurethans sealant.
  • Install window according to manufacturer's specifications.
  • When the window is plumb, level, and square, fasten the window into the framing.
  • Cover side jamb flanges with ZIP System flashing tape. Make sure the jamb flashing extends over the sill flashing on the bottom, and stops midway into the head flashing that will be applied next, at the top.
  • Use J-roller to seal flashing to sheathing. Focus on wrinkles or air pockets, which can become 'fish-mouths', which can allow water to creep in.
—This video is provided by ZIP System sheathing and tape, one of ProTradeCraft’s advertisers. A next-generation exterior roof and wall solution, ZIP System streamlines the weatherization process with an integrated water-resistive barrier and taped seams replacing the need for house wrap or felt, while eliminating the risk of trapped water between sheathing and barrier and protecting against air leakage. View all ZIP System's content.