WHITWORTH Library will close from 1pm on Saturday February 19 for improvements to make the building more energy efficient.
They will include installing new windows.
The work is expected to take around two weeks.
Customers can use any other Lancashire County Council library and online services while the improvements are being made.
Rawtenstall and Bacup libraries are the nearest alternatives for Whitworth customers.
Cllr Peter Buckley, the county council's cabinet member for community and cultural services, said: "This work is essential to improve the windows and make Whitworth Library more energy efficient.
"Unfortunately, we have to close the building while the work takes place for safety reasons."
Overdue charges will be waived from 21 Feb until the reopening date.
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