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How to Install Window Flashing Tape

Window flashing tape forms a barrier around the exterior edges of a window to keep out water. This flashing tape is a sticky and flexible product. You apply it as you install a new window. Learning how to install window flashing tape successfully requires attaching the strips in the right place and the right order. Failure to flash the windows properly during installation can leave your Delaware Valley home vulnerable to water penetration.

How to Install Window Flashing Tape Directions

  1. Start with a bare frame that is ready for a new window.
  2. Measure across the sill and add 6 or 8 inches to that figure.
  3. Cut a piece of tape that length.
  4. Remove the tape’s backing and set half of it along the sill.
    1. About 3 inches of tape should extend up each side of the window frame.
    2. The other half of the tape folds down over the sill against the wall.
  5. Depending on the flexibility of the tape, you may need to slit the corners to fold the tape down smoothly.
  6. If you slit the corners, cut two 6-inch lengths of tape.
  7. Fold and stretch the small tape pieces over the corner slits to create a water barrier.
  8. Use a roller to firmly press the tape completely against the surface.
  9. Now install the new window, making sure that it is level and plumb.
  10. After nailing on the window flange, proceed with the next steps to learn how to install window flashing tape.
  11. Measure the side of the window and add 6 or 8 inches to that figure.
  12. Cut the jamb flashing tape to that length.
  13. Starting at the bottom, apply the jamb tape over the flange.
  14. The jamb flashing tape must extend a few inches above and below the window frame.
  15. Roll the tape against the surface.
  16. Apply tape in the same manner on the other window jamb over the flange.
  17. Measure and cut head flashing at least 6 or 8 inches wider than the window.
  18. Stick the tape across the top of the frame overlapping the jamb flashing.
  19. Roll the head tape firmly.

Tools & Materials

  • Measuring tape
  • Utility knife
  • Roller
  • Window flashing tape

Highly Experienced Window Installers

To prevent costly water damage, do not skip window flashing. The window installers at PJ Fitzpatrick always perform the necessary steps to waterproof a window opening. Our customers have access to a large selection of window types and styles. If you need new windows, talk to us today. You can request a window estimate here.

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We have trained professionals that can help. Contact us today. 1-877-246-4354

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