You couldn't pay Chris Salazar to go out on a North Philadelphia roof Monday in the 90-degree heat.

But he would do it free.

Salazar, an executive for a New Jersey roof-coating manufacturer, and about two dozen other volunteers scaled 32-foot ladders Monday to apply reflective layers of acrylic to the roofs of 20 rowhouses, capping a major energy retrofit on the 1200 block of West Seltzer Street.

Most of the volunteers were attending the four-day International Roof Coatings Conference, which opened Monday at the Sonesta Hotel Philadelphia.

Salazar is chief operating officer of Karnack Corp., based in Clark, N.J.

"What better thing to do than to show what our products can do by helping some people?" he said, as he swabbed a rooftop with a layer of white material that will reflect sunlight, helping to keep the house cool.

The conference sponsor, the Roof Coatings Manufacturers Association, "sees this as a very worthwhile project for its members to take part in," said Laura Dwulet, the association's general manager, who was among the rooftop workforce. Several University of Pennsylvania students also volunteered.

The event marked the conclusion of the second round of work in a home-repair demonstration project called EnergyFIT Philly, sponsored by the Energy Coordinating Agency.

The nonprofit agency, which does weatherization work, said that many of Philadelphia's 331,000 rowhouses do not qualify for energy upgrades because of the poor condition of their roofs - the houses leak so much that any interior repairs are quickly damaged by moisture. So ECA raised funds to overhaul roofs in low-income neighborhoods, concentrating on single blocks to multiply the benefits.

"What we are really attempting to do is bring back the whole neighborhood," said Liz Robinson, ECA's executive director. "It's very important for people who live in rowhomes to understand that you live in a structure that extends the entire block. So the integrity of the block, the structural and thermal integrity, is important."

EnergyFIT Philly rebuilds old roofs, adding insulation and other interior upgrades, including new heating systems. The aim is to reduce energy consumption up to 40 percent per house, Robinson said.

But it's costly. The first phase of the project, in 2014, targeted 30 houses in Mantua for $933,000, more than $31,000 per house. Those costs were paid by a combination of grants from the Oak Foundation, a Swiss charity, and grants from government and corporations.

ECA reduced costs for the second phase of the project, which included 20 houses on West Seltzer Street and six on the 2700 block of Helen Street in Kensington. Its rebuilding technique involves opening the roof from above and injecting the roof cavity with open-cell foam insulation, which saved $6,000 compared with using an exterior spray foam on the roof.

"We're trying to refine, refine, refine and get the cost down," said Robinson.

The target is to accomplish the overhauls at a cost of $15,000 to $20,000 each.

Last year, City Council approved spending $2 million from the Housing Trust Fund on the project. Council President Darrell L. Clarke, who attended a ceremony Monday to mark the roof-coating occasion, regards the EnergyFIT program as an economically efficient way to prevent homelessness and displacement, said his spokeswoman, Jane Roh.

The new administration has not released the $2 million while the project is under review.

"The Kenney administration is in the process of reviewing the system-repair program and our other energy-efficiency programs to determine the best method to leverage these dollars in order to achieve energy savings for low-income households," said the mayor's spokesman, Mike Dunn.

ECA conducted a Coolest Block Contest to select the streets for new roofs. The 1200 block of West Seltzer Street was picked largely because it is an intact block of two-story homes, mostly owner-occupied, that is well-organized under the leadership of block captain Darlene Pope, who recruited 20 of the 30 residents to participate.

"I know there's a lot of people out there in need, so we feel really blessed," said Pope, 61, who added that many residents are elderly and unable to afford the upkeep on their houses.

"This area used to be a rich area, but then it got rundown," she said. "We're trying to build it back up."

amaykuth@phillynews.com

215-854-2947@maykuth

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View a video shot using a drone that recorded Chris Salazar and a group of volunteers applying protective coating to the roofs of some North Philadelphia homes to make them more energy-efficient.

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