At the Edgartown town hall the third-floor ceiling may be falling down. Staff have decamped to the ground and second floors as a precaution against falling plaster and any dust that will be produced by inevitable repair work.

“If the lights are off you can see a load of hairline cracks up there,” pointed out Karen M. Fuller, assistant to town administrator Pamela M. Dolby, yesterday.

Top floor staff first began to notice the cracks several weeks ago. Another warning sign was a widening gap between the ceiling plaster and fire sprinklers. Then on Tuesday last week, a piece of the 100-year-old horsehair plaster fell and shattered on the floor. At this point staff began covering desk areas with plastic sheeting and moving computer equipment downstairs.

The second floor kitchen is currently occupied by park commission administrator and conservation agent Jane Varkonda, where she is sheltered from further plaster fallout.

Technology manager Adam Darack is operating out of the selectmen’s meeting room on the ground floor, sharing the space with several other departments.

“They may have the sink but we’ve got the ceiling,” he said, pointing a finger up at the sturdy-looking, wood paneled ceiling. The color copier from upstairs was functioning in one corner while another sat unplugged in the middle of the room.

The faulty ceiling covers both the second floor and a third-floor mezzanine where the dredge committee, harbor master and technology manager have desks. The selectmen’s office, town administrator and her assistant are also housed on the third floor. The exposed second-floor desks include those for the zoning board of appeals and planning board.

Department reshuffles are nothing new at the town hall — until recently the selectmen were using the second floor as a temporary staging area for their weekly meetings while the first-floor meeting area was occupied by Edgartown library. The library was forced to close its doors last December after a furnace puff-back incident. The Carnegie building on North Water street reopened just after Memorial Day weekend.

In an e-mail sent last Friday to directors of the library, Ms. Dolby joked that the library should return the favor by housing several town hall departments.

After a visit last week, civil engineer Kent Healy noted that the plaster is the main issue, while the roof itself is secure.

“I looked, with Lenny Jason, building inspector, at the vaulted ceiling,” Mr. Healy wrote in the letter. “My preliminary look indicated that the plaster ceiling had pulled away from the roof structure above, by as much as two inches.”

He added that this type of deformation indicated significant deterioration of the ceiling attachment and recommended that no staff or public be allowed under the ceiling until it is secure or until the floor space is protected.

John Anderson, who owns a painting company, was due to come to town hall this evening for an assessment of the extent of the damage and necessary repair work.