Creosote is a highly combustible bi-product of burning wood. It is caused by an incomplete combustion of your wood fuel. When these fuel gases start to cool they condense on the sides of your flue and start to build up. Inspection and sweeping is recommended annually by the National Fire Protection Agency. A 1/8″ of sooty build up or any glaze creosote should be swept as this is enough to cause a chimney fire that could potentially spread to the entire house. Here at Chimney Pro we are certified by the Chimney Safety Institute of America and use only the latest technology and equipment. We come prepared to answer all your questions and leave you ready for the burn season. We also offer a NO MESS GUARANTEE!