The Chimney Safety Institute of America recommends that open masonry fireplaces should be swept at 1/8" of sooty buildup, and sooner if there is any glaze present in the system. This is considered to be enough fuel buildup to cause a chimney fire capable of damaging the chimney or spreading to the home. Factory-built fireplaces should be swept when any appreciable buildup occurs. The logic is that the deposit is quite acidic and can shorten the life of the fireplace. Call Air Duct Cleaning Solutions at 732-349-2000 or visit us at airductcleaningsolutions.com. We charge $150 plus tax for any residential fireplace chimney cleaning. Our Price is 100% guaranteed.