Essential repairs will see the Island Archives on Cornet Street close until January.
But the States says resources will still be accessible online and from staff during the works.
The archives are based at St Barnabas Church where repairs have been ongoing throughout the year.
But the next phase will need key and public areas to be closed off to remediate damp in the chancel and tower.
Visitors won’t be permitted on the site between 10 November and January, but the team will attempt to resolve queries despite the limited service.
Vikki Hart, Island Archivist, said she thanked the community for their patience while the building is out of action.
“This work will be an improvement to the building, benefitting those who use this service,and our team look forward to welcoming islanders again once the work is complete.Once we have a specific date for when Island Archives reopens, we will update the community,” she said.
You can reach out to the archive team on archives@gov.gg or call 01481 224512.
A wide range of records remains available on Findmypast which can be accessed for free at the Priaulx Library or online at familyhistory.gg.