More than £125,000 is to be spent on repairs to the roof of the Mintlyn Crematorium, near Lynn, in a bid to keep bats out.
Council officials will seek a special licence to move the mammals out of the roof space, amid complaints from some funeral directors about the smell caused by them.
They say the work will maintain the roof for another 35 years.
But the project must be completed within weeks in order to stop the animals being disturbed during their forthcoming breeding season.
The work represents the final stage of a £2.4 million project to renovate the facility, which lies off the B1145 just outside Lynn.
Since the scheme was given the go-ahead nearly three years ago, three new cremators have been installed and a new cremator hall built, while the old area was converted into office space.
Energy efficient heating and colling systems have also been installed and asbestos removed from the building.
As part of work on the new extension, a licence was obtained to keep bats out of the old part of the building.
But a report presented to the borough council’s cabinet, which backed the project on Tuesday, said: “During the works, further bat issues affecting the Vestry arose which were not covered by the licence.
“This resulted in complaints being received regarding the severe odours and the possible health impact this might have on occupants of the vestry adjacent to the Chapel, with the fear that these odours may migrate further to the Chapel itself.
“A permanent solution cannot be secured without applying for a further bat licence to exclude the bats from the remaining roof voids.”
The report said mitigation works, including the installation of new bat boxes around the crematorium grounds and a new maternity roost would be needed in ordered to secure the necessary licence.
It also warned that the work would need to be completed by April in order to avoid disturbance during the bat breeding season.
And David Pope, the portfolio holder for ICT, leisure and public space, said: “We felt we had to address the situation.”
Deputy leader Alistair Beales added: “It’s an important facility for the council and council tax payer. We’ll have a facility fit for the future.”