The resignation yesterday of the city’s buildings commissioner, Patricia Lancaster, is polarizing the real estate development community and could signal a symbolic end to New York’s building boom.

A day after Mayor Bloomberg criticized the performance of the Department of Buildings, Ms. Lancaster tendered her resignation. The announcement pitted elected officials who welcomed the news against members of the development community who say Ms. Lancaster is unfairly taking the blame for a sharp spike in construction-related accidents.

“This is a travesty,” the executive director of the New York chapter of the American Institute of Architects, Fredric Bell, said. He called Ms. Lancaster “one of the most capable public employees that I have ever worked with.”

Mr. Bell credited Ms. Lancaster, 54, with changing the city’s Byzantine building code, tackling corruption within the agency, and creating more transparency. He also said that, given the staffing and budget of the agency, it would have been almost impossible for any buildings commissioner to control the number of recent safety violations, which occurred during a period of explosive construction.

It was on Ms. Lancaster’s watch that all five boroughs experienced a building boom. Manhattan saw a 22% growth in the number of building permits issued between 2002 and 2007, according to statistics provided by the Department of Buildings.

So far this year, 13 people have died in construction accidents, one more than the total for all of 2007.

“I don’t think anyone, even some of the people that are so rightfully concerned about development, think that New York should become a museum city where nothing gets developed and built,” Mr. Bell added.

The president of Manhattan, Scott Stringer, an advocate for tougher safety restrictions on construction sites, is calling for the appointment of a new commissioner with a “laser-beam” focus on safety.

“The buildings commission has acted as if these accidents were just collateral damage, and that is just very bad news for workers and neighborhood residents,” Mr. Stringer said. “We need a no-nonsense commissioner who needs to shake up the building department and change how things are done — somebody who is tough as nails and thinks outside of the box.”

Last week, Ms. Lancaster acknowledged that construction plans for the East 51st Street construction site where six workers and one civilian were killed in a tower crane collapse last month should never have been approved by her department because the development violated zoning regulations.

“The last few weeks have laid bare significant problems with the way the Department of Buildings conducts business,” Council Member Jessica Lappin, said, who represents the district where the crane accident occurred.

The city comptroller’s office said it has received 10 claims totaling $204.5 million in property damage and personal injury claims as a result of the crane collapse. On Monday, representatives for one of the victims filed the first lawsuit against the construction companies, seeking unspecified damages.

The president of the Real Estate Board of New York, Steven Spinola, complimented Ms. Lancaster on being tough but accessible, and said members of the real estate community would take a wait-and-see approach to evaluating her replacement. With a slowing local economy, rising construction costs, and a tighter real estate financing market, it is unlikely that building will continue at the same pace.

“We want to work with the new commissioner to limit as many accidents as we can, but we need someone who still permits us to go ahead and build without fear of a reaction if people on site do not dot every ‘i’ or cross every ‘t.’ Building a building in the city is a complicated process, but we accept the fact that we have to do a better job,” Mr. Spinola said.

In a statement, Ms. Lancaster said she was proud of the “groundbreaking work the department has done during my tenure to root out corruption, increase transparency, overhaul the building code, and increase safety for workers and the public alike.”

Mr. Bloomberg said yesterday that first deputy buildings commissioner, Robert LiMandri, would serve as acting commissioner until a replacement is named.