The National Fire Protection Association (NFPA) recommend your chimney should be cleaned and inspected annually.
Any Fireplace, stove or insert that burns combustible materials, such as wood, coal or hardwood pellets should have their chimney’s cleaned & inspected on a regular basis.
When an individual burns combustible materials, those materials create smoke and as the smoke cools it creates a by-product, known as creosote.This creosote is a build up that occurs on the interior linings of the chimney. This creosote can become flammable when this build-up becomes excessive, usually around 1/4″ or greater. Once you have the excessive creosote build up, all it takes is a hot fire or even sparks to ignite the creosote on fire.