Bangor Crematorium's chapel will be shut from 5-24 September.
Funerals will not be held but cremations can still be carried out while improvements are made to keep the facility up to standard.
Crematoriums in Colwyn Bay and Aberystwyth have been told about the closure and to expect more funerals at those facilities.
Gwynedd council's cabinet member for the environment, John Wynn Jones, said: "Every effort is made to minimise such work on the efficient running of the facility, however on this occasion the scale and location of the work combined with the need to remove asbestos materials means that we unfortunately have no option but to temporarily close the chapel facility."
A crematorium's chapel in Gwynedd will close for three weeks for asbestos removal and repair work.