A chimney should be swept anywhere from once a quarter to once a year depending on the type of fuel and the frequency of use, according to the Guild of Master Chimney Sweeps. Fireplaces that burn wood or coal need a quarterly sweeping during periods of heavy use.
Chimneys for gas fireplaces need to be swept annually, notes the Guild of Master Chimney Sweeps. Even though gas fireplaces do not produce soot buildup, there is a danger of carbon monoxide poisoning or fire if a bird's nest or other obstruction forms in the chimney. The Guild also recommends that homeowners clean their chimneys before moving.