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Atherton Residence
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Sebastopol Residence
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Sea Ranch Residence
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Turnbull Griffin Haesloop is an award-winning architecture firm, led by principals Mary Griffin FAIA, Eric Haesloop FAIA and Stefan Hastrup AIA from our San Francisco office. We are a woman-owned business renowned for sustainable, site sensitive design of houses as well as wineries, churches, libraries and independent schools. Our work also includes campus planning, adaptive reuse and historic renovations. An integral part of our practice is interior design, headed by Margaret Turnbull Simon ASID.
We believe architecture is primarily concerned with establishing a "sense of place," inspired by the uniqueness of each site and each client. Since the concept for each of our buildings is rooted in its environment, we are particularly attentive to topography, microclimate, vegetation and solar orientation. We listen carefully to the aspirations and requirements of our clients.
Mary Griffin, Eric Haesloop and Stefan Hastrup collaborate on all aspects of design and continue William Turnbull’s commitment to producing buildings of enduring architectural value. Turnbull Griffin Haesloop is a member of the U.S. Green Building Council, with several LEED accredited professionals.
Raised in Atlanta, Georgia, Mary concentrated in American Civilization at Brown University. She received her Masters of Architecture degree from MIT, where she studied and worked with Donlyn Lyndon. After five years in Washington D.C. with Hartman-Cox Architects, she moved to San Francisco to marry William Turnbull and join his architectural practice.
Mary and partners Eric Haesloop and Stefan Hastrup continue to practice in San Francisco and pursue William Turnbull’s commitment to site sensitive sustainable design. Mary has served on many juries, including the AIA National institute Honor Awards for Architecture. She has taught architectural design at UC Berkeley and will be the Friedman Visiting Professor of Professional Practice in 2008. Mary became a Fellow of the American Institute of Architects in 2006.
Raised in Indiana, Eric graduated from Washington University and then received his Masters of Architecture from Yale, where he studied under Charles Moore, James Stirling and Aldo Rossi. After graduating he worked at Cesar Pelli & Associates in New Haven for three years.
Eric joined William Turnbull Associates in 1985 and worked closely with William Turnbull until his death in 1997. Eric and partners Mary Griffin and Stefan Hastrup continue William Turnbull’s commitment to site sensitive, sustainable architecture and collaborate on all aspects of design. Eric has taught architectural design at Yale College, Stanford, and UC Berkeley and will be the Friedman Visiting Professor of Professional Practice in 2008.
Stefan Hastrup studied art and architecture as an undergraduate at Brown University and at the Institute for Architecture & Urban Studies in New York City. He then attended Yale School of Architecture, where he studied under visiting professor William Turnbull. After receiving a Masters of Architecture from Yale in 1983, Stefan joined Beyer Blinder Belle in New York to work on the renovation of Ellis Island as a museum of immigration. Returning to California in 1986, Stefan continued to focus on the design of museums and other institutional projects at Robinson Mills + Williams, and later at the San Francisco offices of Polshek and Partners.
Stefan joined Turnbull Griffin Haesloop in 1999 and has served as the project architect for several residential and institutional projects. Stefan has been an active participant in community efforts to replace San Francisco’s earthquake damaged Central Freeway with a surface boulevard and new housing.
Raised on a farm in New Jersey, Margaret majored in Fine Arts at Sarah Lawrence College. Having taught high school studio art in Pottersville, New Jersey, she moved to San Francisco where she managed display for the west coast Design Research stores for eight years.
In the late 1970s, Margaret joined her brother’s firm, William Turnbull Associates, bringing her expertise in retail and interiors. She has continued to work with Mary, Eric and Stefan on both residential and institutional interior design projects.

