Mark Kane, project manager for the Bellevue-based construction company, declined to discuss the project with GlobeSt due to a nondisclosure agreement. Callison Architecture of Seattle, the designer, also declined comment.

Not including this latest project, local real estate sources have recently estimated Microsoft's total Eastside occupancy at 8.4M sf, including 4.88 million sf of owned space in Redmond, Bellevue and Issaquah. Microsoft's Redmond campus alone contains 3.84 million sf of offices on 265 acres.

As for future growth, Microsoft holds an option to buy 150 acres in Issaquah for the development of offices in the 2,223-acre Issaquah Highlands master-planned community. Last month the software company pushed back its groundbreaking for up to 2.95 million sf in the Highlands for at least a year, citing difficulty in resolving problems with the city regarding utilities infrastructure and permitting.