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Self-Adhering WindowWrap Flashing Tapes

WindowWrap, manufactured by MFM Building Products, is a patented series of self-adhering and self-sealing window flashing tapes designed to prevent the infiltration of water, moisture, air and sound into the building structure. WindowWrap products are suitable for new construction or renovation projects.

The WindowWrap family of products includes straight flash products, flex configurations for curved openings and sill flashing, as well as low-temperature products that feature a patented PowerBond adhesive system that can be installed in temperatures as low as 25°F. Regardless of the application, MFM can provide the proper product to do the job right.

AAMA-711 Compliant

WindowWrap PSX-20, WindowWrap PowerBond and WindowWrap White comply with AAMA 711 window flashing standards and meet ICC-ES AC148, Report ESR 2783. Meeting these industry standards offers a level of quality assurance for the building contractor.


Recommended Guidelines for Installation

As an LBM distributor, you can provide these helpful guidelines to help ensure that your customer is installing the membrane correctly. Full Installation Instructions are available at

  1. Be sure that the WindowWrap product being installed will meet the project’s required membrane thickness, minimum installation temperature and expected UV exposure time.
  2. Advise that the installer is also responsible to ensure that the WindowWrap SBS adhesive system is compatible with any primers, sealants or caulking that may also be used during the project.
  3. Most structures today utilize a building wrap to cover the sidewalls. Start by cutting an “X” pattern in the building wrap to reveal the rough window opening. Cut the building wrap flush across the sill. Wrap both jamb sections into the rough window opening and attach using staples. At the header section, cut two 45° cuts and fold the building wrap upward to reveal the substrate. Hold in place with tape or staples.
  4. Start the flashing installation at the sill BEFORE the window is installed. The flashing membrane should completely cover the sill and fold out onto the shear wall. This membrane should also extend up each jam by approximately 4-6”. By flashing the sill first, any moisture that may enter the window cavity can “weep” to the outside. You can use either a straight-flash product like WindowWrap PSX-20 or a flexible membrane such as WindowWrap Flex.
  5. Install the window per the manufacturer’s instructions.
  6. Flash each jamb section, making sure the membrane extends above and below the window by approximately 4-6”.
  7. At the header, flash across the header flange, making sure that the membrane is installed directly to the wall substrate. The membrane should also cover the tops of each jamb section.
  8. Once completed, fold the building wrap back over the membrane, secure with staples and cover the 45° cuts with extra pieces of window tape.
  9. Roll the entire membrane firmly with a hand roller to ensure maximum contact of the membrane to the surface, as well as to remove any air pockets or excessive wrinkles in the membrane.

The two most important aspects are to install the sill flashing prior to the installation of the window and secondly, not to wrap the building wrap into the header section of the window opening.

Always read the WindowWrap Installation Instructions, and understand them thoroughly prior to starting the project. Following these general guidelines will greatly enhance the flashing membrane’s performance in preventing leaks and the flow of air into the structure.

For more information on WindowWrap, please visit or call 800-882-7663.

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