Jersey's employment and social security offices needed refurbishing to comply with health and safety laws, the head of the department has told the BBC.
The offices had a £3.5m refit to bring them up to the required standard, said Ann Esterson, controller of Employment and Social Security.
She said the work had to be done because of problems with ventilation and lighting.
She said: "It got to quite a critical stage of it needing works doing to it.
"From health and safety perspectives, we didn't have adequate ventilation for our customers, our lighting was out of date and our heating system was collapsing.
"We had got to the stage where work had to be done, we had no choice."
Health and safety at work legislation on the island is administered by the Employment and Social Security Department.