Norwegian architect Sn�hetta released its preliminary design for the 225,000-sq-ft expansion of the San Francisco Museum of Modern Art.

General contractor Webcor Builders will have to grapple with a compact urban site, currently a maze of alleyways, that is 335 ft long but only 98 ft wide.

The project includes a public promenade with an entrance to the wing, which will sit behind the Mario Botta-designed original that opened on Third and Howard streets in 1995.

A more detailed design, executed in partnership with SF’s EHDD Architecture, is scheduled for completion by the end of the year. Construction completion is set for 2016, though the museum has not announced a start-up date.

According to SFMOMA, the building also introduces a façade on Howard St. that will feature a large, street-level gallery enclosed in glass on three sides, providing views of both the art in the galleries and the new public spaces. At this time, the museum says it is also exploring the creation of a number of outdoor terraces, including one on top of its current building. The Snøhetta building will rise 50 ft higher than the Botta building, and its roofline will be sculpted to frame the skyline of the buildings beyond it to the east when viewed from Yerba Buena Gardens. The new entrance will be accessible from both Howard and Natoma streets and will align with the new Transbay Transit Center being built two blocks east of the museum.

SFMOMA adds that on Howard St., the glass-enclosed gallery and pedestrian promenade will be located on a site currently occupied by Fire House 1 and its neighbor building at 670 Howard St. SFMOMA is designing, financing, and constructing a new, replacement fire station on nearby Folsom St., representing a gift to the city of more than $10 million, that will provide the Fire Department with a state-of-the-art facility that will enhance emergency response time. 

Snøhetta also designed the Bibliotheca Alexandrina in Alexandria, Egypt, and the National Opera in Oslo.