FortiFlex® Butyl

Highly conformable for complex curved penetrations

FortiFlex® Butyl

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Sill pans, arched windows and other curved penetrations complicate installs. FortiFlex® Butyl is a flexible, self-adhering waterproof flashing that is highly conformable, making it ideal for use in these applications. FortiFlex Butyl is constructed from a technically advanced hybrid butyl compound and a high-performance creped film that features exceptional stretch and durability. FortiFlex Butyl can be stretched around tight arcs, including arched windows, irregular penetrations and sill pans. It adheres tenaciously to most common construction materials, including plywood, OSB, aluminum, rigid vinyl, gypsum board, primed steel, concrete and concrete block. The unique butyl formulation maintains high tack even at installation temperatures as low as 10°F. FortiFlex Butyl self-seals to prevent moisture intrusion.

Part of the Fortifiber® 1-2-3 moisture control system, FortiFlex® Butyl is designed to withstand the rigors of the jobsite and the elements, and is backed by an industry-leading 15-year warranty.


  • Exceptional flexibility
  • Installs at low temps
  • 12 month UV resistance
  • Seals around fasteners
  • Aggressive, high tack adhesion
  • Meets AAMA 711-Level 3
  • Part of a complete Moisture Control System


  • 6” x 50’
  • 9” x 50’

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