First and foremost, if a chimney is cleaned it should always be cleaned professionally. Your average homeowner is not equipped to adequately clean a chimney. It requires specialized tools and an understanding of the construction of the chimney to be able to recognize the warning signs of a chimney that needs repair.
The question of how frequently this professional cleaning should be performed is based on a variety of factors. A quick answer is that it should be professionally cleaned on an annual basis. If your chimney has been taken care of regularly, cleaning once a year should be sufficient. However, the answer to this question is also related to how frequently you use your fireplace or woodstove. It depends on the type of wood you burn in your fireplace. It depends on the age of your chimney and how well it has been maintained.
The frequency that you professionally clean your chimney is related to the standards set by the National Fire Protection Association (NPRA). This group also sets the standard for chimney inspections. An annual chimney inspection can give you a better idea of how frequently you should professionally clean your chimney.
The NPRA recommends that you have a basic chimney inspection annually. This inspection will check your chimney for soundness, freedom from deposits, and the clearances that are necessary to operate your fireplace safely. Even if you don’t use your chimney frequently, it can deteriorate due to animals building nests in the flue or deterioration due to many factors including weather.
The NPRA recommends that you have a chimney sweep come in if you have 1/8” of soot built up and sooner if there is a glaze buildup. A soot or glaze buildup of 1/8” or greater is a buildup that is sufficient enough to potentially spark a fire. If you have a factory-built fireplace, you should get your fireplace professionally cleaned when there is any appreciable buildup.
The deposits that build up in your chimney and fireplace are acidic. This acidic soot is corrosive and aside from being capable of starting a fire, it can significantly deteriorate your chimney. Only a professional is capable of safely and adequately cleaning your chimney.