Furthermore, the outlook is brightening because large blocks of contiguous industrial sublet space are scarce throughout the region. "There is virtually no sublet space on the market in Philadelphia County, for example," CBRE reports. In addition, new construction is under way only in Bucks County among all 10 of the counties CBRE studies. Of the 10, five surround Philadelphia, another is the Lehigh Valley, PA market, and the remaining four are in Delaware and Southern New Jersey.

Of the Pennsylvania counties, at 17.4%, the Lehigh Valley market has the highest vacancy rate. At 4%, Chester County has the lowest and, not incidentally, among the highest average asking rental rates--$5.59 per sf. The average asking rental rate in Montgomery County is $7.06 per sf, the highest of all in the area, and the vacancy rate there is 10.2%.

Philadelphia County's vacancy rate reached 12.4% during third quarter and the average asking rental rate remained at $4.12 per sf, exactly the same as in Delaware County, where the vacancy rate is just 5.3%, according to CBRE.