Owners of second-tier office buildings in Pittsburgh are increasingly looking to convert them into apartments to take advantage of rising residential rents as well as a revitalization in the once-dying steel town.

Next month, local developer Millcraft Industries of suburban Washington, Pa., will begin renting units in a 16-story former state office building that is undergoing a $45 million conversion.

Another developer, PMC Property Group Inc. of Philadelphia, last year began leasing some 158 rental units carved out of a nearby 12-story former office property previously occupied by Verizon Communications Inc.