Citing a study that shows schools across Pennsylvania have wasted tens of millions in taxpayer dollars on roofing, a state legislator has introduced a bill to open major construction projects to competitive bidding.

State Rep. Jesse Topper said his bill, now in the State Government Committee, would improve on so-called cooperative purchasing.

In cooperative-purchasing agreements, schools pool their money to purchase items such as classroom and cafeteria supplies. School officials say that by using a centralized system they save cash and time.

But Topper questioned the wisdom of using the system for roofing and other construction projects.

"Co-op purchasing has some things it can do for time factor and familiarity, but we need to balance a lot of that to ensure we're getting the best bang for our buck," said Topper, a Republican who represents parts of Bedford, Franklin, and Fulton Counties.

By using cooperative purchasing instead of competitive bidding, school districts overspent by more than $100 million on school roofing projects from 2005 to 2010, according to an assessment by market research firm Ducker Worldwide commissioned by the Coalition for Procurement Reform, which represents national and state consulting and construction companies.

The researcher interviewed 52 roofing contractors and architects and analyzed 73 school district contracts. It also collected more than 80 price points to calculate the total cost per square foot of installed roofing.

"The money that's being wasted through the co-ops could be spent toward the items that a school needs," said Janial Mack, spokeswoman for the coalition.

Topper's bill would outlaw the practice specifically for construction projects. For Pennsylvania public schools that often struggle to make ends meet, the bill's backers believe, competitive bidding would save money.

Topper has received mixed responses from school districts on cooperative purchasing, he said. Some like it, he said, but others "really feel they've gotten burned on cost or quality."

Still, many school officials maintain that cooperative purchasing agreements offer a valuable option for construction projects, said Jay Himes, executive director of the Pennsylvania Association of School Business Officials.

"It can assure quality, reduce maintenance costs, and provide consistency," Himes said.

Cooperative purchasing agreements have been challenged in other states, including Virginia and Indiana, and at the school district level in Baltimore County Public Schools.

At the Big Spring School District in Newville, west of Harrisburg, the district originally received a bid for a middle school roof project from a cooperative for $2.4 million. The open bid for the same project cost $1.4 million, according to Mack's testimony at the state Capitol.

Mark J. Sobek, president and founder of a Wilkes-Barre roofing consulting firm that is a member of the procurement coalition, said he is upset that districts are overspending on roofing.

"It's offensive to me," he said.

In Pennsylvania, the Central Susquehanna Intermediate Unit oversees the state's cooperative purchasing agreements for the Association of Educational Purchasing Agencies. The intermediate unit receives about a 2 percent discount on each project, said Jeffrey Kimball, director of cooperative purchasing services.

Kimball said the products that the association offers schools may be more expensive, but are of higher quality than other roofing contractors could offer. He added that an open bid wouldn't take into account the cost to design and monitor the project, as a cooperative does.

Cooperative-purchasing critics "kept bringing up the easy button," Kimball said. "It's not so much what's easier, it's about what's giving you the best."

Kimball said school districts, not the state, should be able to decide if cooperative purchasing is the best method for them.

"At the end of the day," he said, "that's what has to be preserved, so that the districts are able to make the best choice for their taxpayers."