It used to take 90 days to knock over a derelict rowhouse in Philadelphia, and three contracts - one for demolition, one for slapping stucco on the neighboring homes' walls, and one for fixing the adjoining roofs - says Frances Burns, the city's Licenses & Inspections chief. Average cost each year from 2006-09: $24,000 per house, according to L&I data.

Under newly revised L&I bidding procedures, it now takes thirty days and a single contract - and costs an average $13,000 - to knock down a rowhome, Burns told me over the growl of a front-end loader tearing into the rear of the first of four decaying three-story homes that city contractor William Pecarsky is knocking over in the 1700 block of North 21st St., in the North Philly neighborhood west of Temple University. The city typically pays the cost, and gets paid back when or if the properties are sold.

If the city budgets its usual $8 million to $10 million for demolitions when this year's budget gets through, crews will knock over 600 abandoned city homes this year -- up from 400 fewer in each of the past four years, according to L&I data.

Why so much cheaper? Partly it's the weak economy, which has made contractors willing to work for less. And partly it's reforms in the city's demolition process, according to Burns.

Under Burns, a Nutter appointee who held an L&I finance job in the first Street administration, the city has combined the three-part contracting process into a single deal, shortened the time frame to one month from three months, stoped allowing most contract change orders, and bid jobs including multiple, neighboring homes, instead of house by house, said Scott Mulderig, chief of L&I's Emergency Services and Abatement unit.

Lower demo costs are good for the taxpayers, and good for the shrunken city budget. Maybe not so good for contractors like Pekarsky. "It's a squeeze," he told me, watching his crew from across 17th St. "But it's a better system."

For one thing, he says he's less likely to get sued by angry neighbors, because his men seal the neighboring houses quickly, instead of waiting for other specialized contractors to get around to it, as under the old system. "We'll stucco that house right away and fix the boards" along the neighboring roof.

Haven't lower payments driven contractors out of the business? No, says Mulderig: "We had 13 registered demolition contractors before, and we still have 13."