Biogen Idec to move its main offices to Weston

Biogen Idec said over time it will convert about 375,000 square feet of office space in Cambridge into laboratory facilities. (Essdras M Suarez/Globe Staff/File 2008)

Biogen Idec Inc., one of Massachusetts' largest biotech companies, will move its headquarters from Cambridge to an office building being built in Weston adjacent to routes 20 and 128.

The 350,000-square-foot building, which the company plans to move into in 2010, marks the largest lease deal in Boston's suburbs this year, according to several real estate brokers. The construction project will be managed by Boston Properties Inc.

Biogen Idec said it will save money by moving management and administrative functions to the suburbs. The company is likely to pay an annual lease rate of close to $45 a square foot, according to several brokers, while space in Cambridge can cost more than $60 a square foot.

Between 400 and 600 employees will move to the new building in Weston, the company said. Biogen Idec has 1,800 employees in Massachusetts and 4,500 worldwide.

The company now occupies about 960,000 square feet in Cambridge, including space for offices, manufacturing, and research.

After the Weston move, the Cambridge headquarters on Main Street near Kendall Square will initially remain vacant. Over time, however, the company will convert about 375,000 square feet of office space into laboratory facilities, expanding Biogen Idec's research and development presence in the heart of the state's biotechnology cluster.

"The Weston site gives us the flexibility to allow us the future growth in an area where real estate is less expensive," said Jennifer Neiman, a Biogen Idec spokeswoman.

In addition to its sheer size, the lease deal is notable because it is one of only a few recent "build to suit" transactions in which a developer attracts a tenant and then constructs a property to specific requirements.

Biogen Idec's move is also a bright spot in what has otherwise been a dismal year in Boston's suburban office market.

In 2007, 735,000 square feet of additional office space was leased in the Route 128 area that stretches from Needham to Lexington, said Mark Roth, executive director in the Boston office of Cushman & Wakefield Inc., a worldwide real estate firm. In 2008, the same area will have net absorption of just 25,000 square feet - the surplus of space being leased compared with space being vacated - out of a total of nearly 22 million square feet.

The Weston site had previously been used as a sand and gravel pit. After the building is developed, the property will include 74 acres of open space and water.

"It's a one-of-a-kind site," said Bryan J. Koop, senior vice president of Boston Properties.

DTZFHO Partners LLC represented Biogen Idec in the negotiations.

Jeffrey Krasner can be reached at krasner@globe.com.