With commercial real estate in San Francisco showing new muscle thanks to the tech boom, Tishman Speyer plans to build a rare speculative office building in the Foundry Square complex at Howard and First streets, south of Market Street.

Rendering courtesy of Tishman Speyer

Foundry Square III

The 10-story Foundry Square III was designed by Studios Architecture, which also designed Foundry Square I, II and IV, and will be built by Webcor Builders, according to Rick Matthews, spokesman for Tishman Speyer.

Construction is set to begin in July with completion scheduled for the end of next year.

Matthews said there was no official announcement of the new project. Local news reports were based on an email that was sent privately to “a few local brokers.”