Attorneys representing a former graduate assistant told ABC11 that independent testing started first thing in the morning.
The work will take multiple days. It will involve about 40 people working inside Poe Hall. The number includes individuals who will be conducting independent testing as well as those from NC State.
Access to the building is granted under the agreement that any findings remain confidential.
Poe Hall has been closed since November last year when toxic PCB chemicals were discovered. Those chemicals have been linked to increased risk of diseases, such as cancer.
The university has been doing testing and the second round was completed last month.
NC State ordered to allow independent testing at Poe Hall
The primary source of PCBs was identified in the building's HVAC system.
NC State said the next steps include working with the EPA to remedy the problem.
ABC11 asked NC State Chancellor Randy Woodson how much the work could cost or when it would start.
"We understand the environment in Poe Hall now. We know what we need to do. We've had good conversations with EPA to remediate the contaminates," Woodson said.
He said funding for remediated project remains an issue.
"It's a state building, so we need to have clarity on authority and financing to be able to move forward," he said.
Woodson said once the University does figure out the funding, it could take up to three years to fix the problems and reopen the building to the public
NC State said in a statement that it's pleased an agreement has been reached.
"We expect that all inspections and testing will be complete by early August. While the building remains closed and access limited, this approach ensures that the interested law firms are able to gather the information they are seeking in an orderly process prior to any remediation of the building."