WANT TO BUILD something in Philadelphia? Better hope you don't have a neighbor or Council person who's cranky. If you do, they have a powerful tool to bring your project to a halt: the zoning code.

The code splits the city into residential, commercial, industrial and mixed-use areas, and gives rules about development for each. In theory, it exists to prevent, say, a dairy farm from getting plopped down at 15th and Market.

But the code hasn't been rewritten for more than 50 years, meaning that we have a lot of outdated rules. It also means that City Council has made plenty of tiny amendments that ban a barbershop here, a nail salon there. The end result: a code that is a complicated monstrosity, requiring special permission for many reasonable projects.

Eva Gladstein, executive director of the Zoning Code Commission, said that change is necessary.

"You need to have a zoning code that sets up the basics and then gets out of the way," she said.

In 2007, voters overwhelmingly approved a ballot measure calling on the city to rewrite the code. This led to the creation of the Zoning Code Commission, which has worked since to write a code that is less baffling and less political.

Council has been debating the new code and could vote on it this fall. But it could also delay the decision, possibly for years, laying waste to the thousands of hours of work from the public and the commission.

Getting special permission for development would then remain a major stumbling block to bringing new business to the city.

Each year, 35 percent of about 7,000 proposed developments require a variance. Alan Greenberger, executive director of the City Planning Commission, said that this percentage is "off the charts." He said the city's zoning board sees about the same number of cases as New York City's.

The board has traditionally given great deference to community groups and district Council members. This situation is easily abused: Several past Council members, including Rick Mariano and Leland Beloff, have been thrown in jail for requesting kickbacks in return for supporting zoning measures.

The code has stymied developments that could have benefited the city. For example: Parts of Germantown, Fishtown and Kensington are still zoned "industrial," though the industry there is long gone. Greenberger said that this makes it hard to develop abandoned factories.

The code has also been used to prevent projects that are arguably in the city's interest but that no one wants in his back yard. Halfway houses, methadone clinics and a dialysis center have all been opposed by neighbors and were either stalled or stopped by the board.

Greenberger said that the zoning code has kept outside companies from opening up shop here.

"We're the fifth-largest city in the U.S., but during the height of the economic boom, from 2003 to 2007, we were the only one of those five that didn't see significant outside development," he said.

Changing the code is not without controversy. Some believe that heavy regulations and a slow process protect neighborhoods from unwanted development. Many Germantown residents are happy that variety stores are banned in their area, for instance.

But Greenberger stressed that concerns like these can always be addressed later.

Council is also considering a proposal from Councilman Bill Green to ban or require a "special exception" for certain kinds of developments, including restaurants and bed-and-breakfasts, until the city is "remapped" - meaning that when new decisions are made about which areas are residential, commercial, mixed-use, etc. That could take more than five years. Green said that he is responding to residents' concerns; critics say that his proposal will block much-needed development.

Either way, if Council doesn't meet a deadline to hold its last hearing on the code by the end of the month, Gladstein said that it's unlikely that the bill will pass this year. That could lead to the city not having a new zoning code for years, because newly elected Council members might avoid tackling the issue.

"If we don't do it now, forget about it," said Councilman Frank DiCicco, a zoning-reform advocate. "It won't happen for another 20 years."

Holly Otterbein writes for It's Our Money, a joint project of the Daily News and WHYY funded by the William Penn Foundation that works to shed light on where your tax dollars go. For more visit www.ourmoneyphilly.com.