Rancho Palos Verdes chimneys and the draft question
Ground movement around the Portuguese Bend landslide area can open joints in a flue liner without any crack showing outside. Through that gap, smoke leaks into an attic or a wall cavity, and the first sign is often a smell upstairs rather than smoke at the hearth. Downslope lots add another snag, with the chimney top sitting below the uphill neighbor's roofline. Whatever the stack looks like, the first job is the same: watch which way the smoke goes at the damper, then work out why.
