ST. LOUIS—Although the top office buildings in the St. Louis region saw vacancy rates tick up recently, since 2008 the group as a whole has seen consistent growth in occupancy and rents, according to JLL's 2015 Digital Skyline, its study of the top office buildings throughout the US. Six of the region's 13 Skyline properties are in suburban Clayton, and with rents there setting records, company officials believe a spec office building could rise in the future, perhaps by 2018.

“Clayton is commanding the highest rates,” David B. Steinbach, a St. Louis-based executive vice president with JLL, tells GlobeSt.com, primarily because it has the four newest properties. This includes the Plaza in Clayton, Centene Plaza, Shaw Park Plaza and 8235 Forsyth Blvd., all constructed since 2000. The last tower built in the St. Louis CBD was the 42-floor Metropolitan Square in 1989.

In fact, the four top trophy properties in Clayton now command asking rents 44% higher than the rest of the Skyline properties, “the widest gap we've seen since 2010,” Steinbach says. “Tenants looking for space in Clayton are not getting their first choice in offices,” and JLL expects this robust level of activity will spread to the other class A buildings. The company rates the regional market as neutral, but by 2017 it will switch to a landlord-favorable market.