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How do cost estimators determine overages?

The costs for all of the 18 projects in the Medford School District's $189 million bond program exceed what a facilities planning committee estimated a year ago.

The new estimates come from professional cost estimators who have reviewed the scope and design of the projects and know what's happening in the construction market.

The facilities planning committee was faced with the unknown of what precisely had to be done in each building, calculating cost on estimated square footage of renovation and new construction and applying an average per-square-foot cost. No engineering studies had been conducted on the buildings prior to the bond election, so the extent of the need for asbestos removal and reinforcing walls and roofs came as a surprise.

"In the early stages of a project, people look at historical data to try to guess how much it might cost," said Sharon Kennedy, principal of Seattle-based Robinson Co., the cost estimating firm that provided the estimate for construction of a new South Medford High School.

District officials typically calculate a regional average cost per square foot or look at what it cost to construct their last school to come up with an estimate for projects.

"The problem is that a lot of areas like Medford and Seattle find that what they spent a few years ago is no longer applicable," Kennedy said. "The Medford district isn't by itself in experiencing rising costs. It's been happening to everybody, at least since 2004. It's created a lot of anguish."

Inflation has gone up from 2 to 3 percent a year to 6 to 12 percent in the last few years, affecting every component of a project, from labor to materials.

As the plan develops and the project scope is defined, estimators begin to calculate prices by how many cubic feet of concrete, siding, glass and doors will be needed for the project and what the going rate is for those materials.

Yet, if there is a delay between the time the estimate is made and construction begins, unforeseen market developments such as the rising price of copper and steel could influence the final price, Kennedy said.

"You look for trigger points like the time of year when the project goes out to bid," Kennedy said. "If there are a lot of projects going out to bid, sometimes the costs go up."

High schools typically cost more per square foot than elementary schools because of athletic fields, gymnasiums, locker rooms, specialized science classrooms and the need for more durable materials because of the traffic flow of pupils, she said.

"Does the building cost more (in actual construction)?" she said. "Probably not, it probably costs less, but it's all of the stuff you put in it."

Reach reporter Paris Achen at 776-4459.

or pachen@mailtribune.com.