Creosote is a highly flammable, tar-like residue that builds up inside chimneys from wood burning, with an ignition point of just 451°F—the same as paper—and can burn as hot as 2000°F, creating dangerous chimney fires that damage mortar joints, spread to the roof or attic, and even endanger neighboring homes. For this reason, fire departments recommend professional chimney cleaning and inspection after every half to full cord of wood burned to remove creosote, check for cracks, deteriorated mortar, proper clearances, and spark protection. Gas fireplaces, while not producing creosote, still generate soot and require regular cleaning. With gas logs, NFPA codes require the damper remain open, which can increase heating bills and cause backdrafts—making custom glass doors the best solution for efficiency and safety. Gas inserts, on the other hand, are sealed systems, offering greater heat efficiency and fewer issues compared to gas logs.