"Think of them as a gentle form of densification," writes Inga Saffron on a growing Philadelphia trend. Faced with space constraints, many rowhouse owners are tacking third stories onto two-floor structures originally built for immigrant workers.
"These vertical additions, sometimes called 'overbuilds,' have always been a staple of rowhouse life in Philadelphia. But thanks to a decadelong boom in the real estate market and a change in the zoning code that allows taller houses, homeowners have embraced the overbuild with a vengeance."
While overbuilds have contributed to gentrification in some areas, they have their benefits. "Large suburban homes are still the norm in America, and overbuilds help Philadelphia compete by making it possible for people to continue living in the city as their families grow."
From an aesthetic angle, Saffron critiques an existing rule requiring third-floor additions to be set back eight feet from the front of the structure. "But why? Philadelphia has plenty of three-story rowhouses, and developers who build new houses aren't required to set back the third floor. What is the logic for pushing back the new structure, especially in neighborhoods that aren't part of a historic district?"