Classic view of Fallingwater home and museum in Mill Run.

Pennsylvania

Fallingwater

Protecting the integrity of Frank Lloyd Wright’s architectural masterpiece

  • Category

    Roofing Solutions

  • Completed

    2026

  • Type

    Historic Preservation

  • Size

    Flashing above waterfall

Challenge

Tucked into the Laurel Highlands of southwestern Pennsylvania, Fallingwater was designed by Frank Lloyd Wright in 1935, to serve as a retreat house for department store owners Liliane and Edgar J. Kaufmann Sr. In 1963, Edgar Kaufmann Jr. donated the house and land to the Western Pennsylvania Conservancy, which opened it to the public. In 2019, Fallingwater became a UNESCO World Heritage Site, recognized as part of the “20th-Century Architecture of Frank Lloyd Wright.”

Frank Lloyd Wright’s organic design placed the house directly over moving water to create a connection with its surroundings. However, minimal drainage and lack of flashing details created ongoing waterproofing issues across the sweeping terraces and rounded edges, which heightened the need for high-performance waterproofing. As a historic preservation project, any waterproofing solutions implemented had to be virtually invisible, allowing the property to be restored to its original likeness and design intent, which are key requirements to retain its World Heritage designation.

Solution

As part of the $7 million effort to remedy decades of water infiltration, Siplast solutions were specified to address the historic home's complex roofing and waterproofing challenges.

  • Robust SBS waterproofing 
    Siplast Teranap® Waterproofing Membrane, a premium multi-ply SBS-modified bitumen waterproofing system, was selected for its proven performance. The Teranap® system provides the appropriate surface, even water distribution, and minimizes wear under aggregate.
  • Modern-day solution to unique flashing conditions
    Siplast Parapro® PMMA Flashing System provided waterproofing and concrete protection on the bullnose edges without sacrificing design intent. This prevented water from reversing into the structure by naturally forming a drip edge, guiding water down and away from the building.
  • Visual integrity preserved
    Siplast provided custom Pro Color PMMA matte finishes for exposed flashing areas, ensuring that visible elements of the waterproofing system blended seamlessly into Wright’s natural palette. All color-matching efforts were carefully vetted to meet both functional and aesthetic requirements. Siplast Pro Color Finish, a fast-curing PMMA resin, forms a covalent bond with the Parapro flashing system, providing a long-term and renewable solution.

From early assessments to system design support and on-site implementation, Siplast brought the technical expertise and innovative solutions required to protect an iconic masterpiece of modern architecture.

See the detailed cross-section here.

Systems

Click here to download the

project profile
© by Christopher Little, courtesy of Western Pennsylvania Conservancy
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PMMA Flashing Resins

Parapro Flashing Resin, when individually catalyzed, is combined with polyester fleece to form a monolithic, reinforced waterproofing flashing membrane system. Parapro Flashing Resin is designed for use in conjunction with a variety of Siplast roofing systems and waterproofing systems for flashing details and as a repair material.

  • Available in summer and winter grade.
  • Available in white or light gray.
  • Supplied in resealable drums with locking rings.
View flashing brochure