The commission agreed to transfer $60,000 from the county's general fund reserve to cover the potential cost of what is expected to be a first round of repairs.
The work will replace leak-damaged lentils and windows in the courthouse.
The $60,000 figure doesn't count a new roof or repair or replacement of damaged rafters or disposal or remediation of any hazardous materials if any are found once work begins.
BurWil Construction Co. of Bristol was the only firm interested enough to submit a proposal to do the work, County Purchasing Agent Nelda Fleenor told county commissioners earlier this month.
BurWil will begin work at the courthouse as soon as the company's crews put the finishing touches on the county's new jail facility - set to open May 1, and planned to operate in addition to the county's current jail.
The courthouse also needs a new roof - but damage from leaks must be repaired first to make sure workers can climb on the building without fear of a collapse, Claude Smith, construction project manager for the county, said last month.
BurWil offered to do the work for "cost plus 10 percent fee and 5 percent overhead" with a guaranteed maximum price of $60,000.
Sullivan County's fiscal year 2007 budget included $62,500 for county building renovations. The fiscal year covers county finances from July 1, 2006, until June 30, 2007.
According to a recent budget report from the county's office of accounts and budgets, that renovation fund had an available balance of less than $30,000 as of Jan. 31.
The commission also agreed Tuesday to ask the Tennessee General Assembly to give the county permission to hike fees for filing court cases by up to $25.
The money will be used to improve security at the county's 14 courtrooms in four different facilities in Blountville, Kingsport and Bristol, Tenn.
Sheriff Wayne Anderson said 33,000 court cases were filed in the county last year. If the state approves the necessary change in law, and the County Commission votes to go the full $25 increase, the hike could generate more than $800,000 per year, Anderson said.
In other business Tuesday, the commission rejected Commissioner Wayne McConnell's call for a nepotism policy for the county - to prohibit county employees from hiring their family members or live-in mates.
McConnell first proposed a policy to ban allowing relatives to work for one another in county departments last April. But his proposal failed to gain much support among fellow commissioners. Some said there was no point in commission action at that point because the state legislature's session was coming to a close and it wouldn't reconvene until this month. The Tennessee General Assembly would have to approve a private act in order for Sullivan County to implement a nepotism policy.