King Street Properties broke ground Wednesday on a rare type of construction for Route 128: speculative lab and office space.

While the Route 128 technology corridor has been viewed recently as an economical alternative to Cambridge for technology and biotech companies, construction has been largely build-to-suit. The spec 145K SF lab and office building at 828 Winter St. in Waltham is scheduled for completion in mid-2018 with Transwestern Consulting Group providing leasing services for the project.

King Street purchased 830 Winter St., a 185K SF Class-A lab building, and an adjacent property in August 2015 with the intent of developing it amid Waltham’s rise as a life science destination. The new three-story lab building at 828 Winter St. will feature a 48K SF floor plate on each level.

“Since 2006, employment in Greater Boston’s life sciences industry has grown by 32%, but new lab construction has not kept up with demand,” King Street Properties senior associate Tyson Reynoso said.

The Waltham and Lexington lab submarket is extremely tight. There has been a 178% increase in lab inventory since 2004, but the vacancy rate has dropped to 0.7% in Q1 2017 from a high of 34% in 2004, according to Transwestern.

“The suburbs have begun feeling the pinch of constraint in laboratory space that has been an issue for Cambridge,” Transwestern partner Eric Smith said. “King Street Properties is addressing this demand with 828 Winter St., which will appeal to life sciences users that are looking to either establish or expand in the market.”