Topeka ? Scaffolding now encloses the southern side of the Kansas Statehouse as workers start a four-year, $39 million project to clean and repair the building’s crumbling exterior.

Construction crews plan to wash the rock surfaces this month and begin bringing in cottonwood limestone next month to replace broken and damaged stonework.

Statehouse architect Barry Greis sees the need for the repairs every day. Sitting in his office are 50-pound chunks of stone that fell off the Statehouse facade with the gentle prying of a screwdriver.

Workers have also videotaped footage showing that the building’s concrete ledges have a lot of spalling, or places where the material has chipped off, similar to what happens to driveways and sidewalks.

“There were some mistakes made in past repairs done,” Greis said. “We didn’t realize the extent of the damage until we got up there.”

Past exterior repairs were estimated to last 10 to 15 years. Greis said the current project should protect the exterior for 40 to 50 years.

Crews have already tested the entire exterior of the building, creating a makeshift map of each stone’s durability.

Workers will replace damaged stonework on the south face before moving on to the west, north and east faces, expecting to complete the job sometime in late 2011. That’s about when renovations inside the Statehouse are scheduled for completion.

Officials originally thought the exterior work would cost $10 million, but had to boost the estimate an additional $28.8 million when they inspected the limestone, Greis said.

The entire Statehouse renovation is expected to cost taxpayers $285 million, up from an original estimate in 1999 of $120 million.

State officials said the increase came mostly from big jumps in labor and material costs and additional work not included in the original plans.