Although the fix to the roof of the new Butler County office building could cost as much as $50,000, the nearly $12 million project remains under budget.

John Campbell, director of county facilities and operations, said in an interview the project’s roughly $500,000 contingency fund won’t be tapped into because contracts to do the work came in under budget and some changes to the scope of work saved money.

The error occurred when steel beams and metal sheets for the building’s roof were fabricated and installed flat instead of sloped to drain rainwater into the gutters.

The problem is being corrected by installing sloped insulation and a new rubber top.

The county commissioners discussed the mistake at their meeting Monday.

Michael Preston, senior associate of the Butler division of the architectural firm Stantec, said the mistake should have been caught sooner by multiple companies involved in the process.

Commissioner Bill McCarrier said the county would determine if any party is liable for the alteration’s cost.

The South Washington Street building, which has four levels, will house county human services.