Drywall often presents a cost that contractors can see into about as well as they can see through the product itself, Professional Builder magazine reports.

In a column on the magazine's website, Charles P. Schneider, CEO of Builder Sourcing Corp., offers some ways construction managers can get a handle on what they should be paying for turnkey installation, even when drywall may have 30 percent price swings in a year.

Most important, Schneider says, is to unbundle the cost of the drywall and the needed supplies – screws, tape, mud – from the cost of labor. Frequently, labor comes with the material, and it's not unusual for contractors to get only a lump charge, he says.

"We learned that for a category that was relatively easy to manage and understand, little data were available to help the builder validate or justify the costs being paid. The only way costs could be analyzed was by comparing bids from competing drywall companies," Schneider writes.

To get a handle on realistic quantities, builders can use software to spec how much drywall is needed, Schneider notes. To gauge the current market and what turnkey suppliers are charging, they can check online prices at Home Depot and Lowe's.