Twin Cities office vacancy decreased slightly during the third quarter of 2014 to 16.6 percent while existing tenants requested more improvements and longer leases, according to new data from Jones Lang LaSalle.

This is due, in part, to the rising costs of new construction, the real estate firm concludes – which is being spurred by a glut of commercial development projects in the Twin Cities metro area.

These projects, including the "new Vikings stadium, numerous build-to-suit office projects, multiple repurposing projects, and substantial industrial, multifamily and hotel" activity, have led to an extremely tight labor market for construction.

Jones Lang LaSalle produces statistics and insight on the office and industrial markets quarterly. It's Q2 survey reported an office vacancy rate of 17.2 percent in the Twin Cities.

The metro area is basically on par with national rates. Reis Inc. released its preliminary national data on Wednesday, finding national office vacancy at 16.8 percent.