Haven't cleaned my chimney since moving into my house in 1989. But then, I seldom use it so hope it won't be a problem.
Was going to post this under Nords's thread about leaking roofs but thought it more appropriate under this chimney thread: I kept getting leaks above my fireplace everytime it rained. Thought it was the roof or flashing around my chimney. Called 2 different roofers out to fix it. One guy put more flashing on, and the other guy put some kind of caulking near the base of the chimney where it meets the roof. Neither of these "fixes" helped. Decided to call a chimney/masonry specialist. Come to find out it's my chimney that's the problem. Unfortunately, the chimney is very large and made of "Georgia" (?) sandstone (pinkish, beige-ish color), which is not the kind of material to use for chimneys. Bottom line: It will cost me $5,000+ for partial chimney reconstruction.