Smoke leaking through cracks you cannot see from the hearth

"We smell smoke in the upstairs bedroom, but only when the fireplace is going." That sentence points to a leak in the draft path, not a draft problem at the hearth. A chimney is a sealed tube, and it only works while it stays sealed. When a clay flue tile cracks, or the mortar between two tiles washes out, smoke finds the gap and travels sideways into the masonry, the framing or the attic. Some of it reaches rooms that have nothing to do with the fire. The same gap works in reverse. Cool outside air seeps into the flue, mixes with the rising smoke and slows it down, so the fire draws weakly and smoulders. Smoke that smoulders makes more creosote, which coats the crack and hides it. This is also where carbon monoxide becomes a real concern, because a leaking flue can carry it into living space without any visible smoke at all. If you notice a smell away from the fireplace, stop burning until the cause is found, and keep a working CO alarm near the bedrooms.

Water is the other half of most repair calls. A chimney crown is the cement cap that covers the top of the brick around the flue, and once it cracks, every rain soaks into the masonry below. Wet brick stays cold for days. A cold flue gives a sluggish draft, and damp creosote gives off a sour smell that drifts into the room when the house warms up. Over time the water breaks down mortar joints, rusts the damper frame and lets the brick spall. Southern California adds earthquakes to the mix. Even a modest shake can open a joint, shift a tile or separate the chimney from the house by a finger width, and the damage is often hidden from the hearth. Here in Pacific Palisades, where many chimneys face both marine air and canyon wind, we see all of these together. A repair that fixes only the visible crack while the crown keeps leaking will not last, so we trace the water and the smoke before we pick up a trowel.

Each fault has its own repair, and the job is to match one to the other. Open joints in the brick are raked out and repointed with a mortar that suits the age of the chimney, since a hard modern mix on soft old brick can make the brick crack instead of the joint. A rough or stepped smoke chamber is parged, which means coating the walls with a smooth layer of refractory mortar so the smoke slides up instead of tumbling back toward the room. Cracked crowns are patched when the crack is small and rebuilt when the cement has broken into pieces, with an overhang that throws rain clear of the brick. A flue with many cracked tiles, or tiles that have shifted after a quake, usually needs a new liner rather than a patch, and we explain the stainless and cast options when that is the case. Every repair is priced in writing after the inspection, with photos of the fault, and you approve the price before any work begins on the chimney.

Local conditions decide some of the details. On houses close to the water in Malibu and Santa Monica, we use stainless parts for anything metal, because galvanised steel rusts through in a few seasons of salt air. In Pacific Palisades, where the Palisades fire of January 2025 left many chimneys exposed to heat and ash, we check crowns and liners for heat cracking even where the house itself was spared. Older Brentwood and Beverly Hills homes often have brick chimneys with lime mortar, and those need a softer repair mix to stay sound. After a repair, we run the draft test again so you can see the smoke rise straight up the flue without curling back at the lintel or leaking anywhere it should not. If the repair involves the cap or the roof joint, we point you to those pages so you can read about the options first. When you are ready, use the call button on this page or send a message through the contact form with a short description of what you have noticed.