Chimney Inspection in Los Angeles

Water accounts for a large share of what an inspection finds, and it announces itself in ways that are easy to see once you know what you are looking at. Reading the signs is not the same as fixing them — what follows is what an inspection establishes, and each sign points at a different repair.

Staining on the chimney breast, the ceiling beside it, or the wall below the roof line. It often appears some distance from where the water actually enters, which is why the stain is a starting point rather than an answer.

Damp or discoloured masonry that stays wet when the wall around it has dried, and efflorescence — the white powdery deposit left when water moves through masonry and evaporates at the surface. The deposit is evidence that water is moving through the chimney.

Crown damage at the top of the stack, where cracking or a missing overhang turns the surface meant to shed rain into one that channels it in, and flashing problems at the roof line, where lifted metal or aged sealant opens the joint between two materials that move at different rates.

Mortar deterioration, which makes the masonry itself the water path. Once joints have receded there is no single hole to point at, which changes what the repair has to be.

A great deal of the Los Angeles housing stock is old enough that its chimneys are unreinforced masonry — brick and mortar, built before reinforcement was standard practice. That shapes what an assessment here is looking for.

Weather exposure is uneven, not mild. The Southern California pattern is long dry stretches broken by intense wet periods, which is harder on masonry than steady drizzle: dry masonry absorbs heavily when the rain finally arrives, and the damage surfaces in the seasons afterwards. Exposure also varies sharply across the county — a chimney in Santa Monica contends with salt air and marine damp, one in Santa Clarita with wide daily temperature swing, one in Pasadena often simply with age.

Seismic movement is worth naming, carefully. Cracking can have several causes — water, thermal movement, settlement, age — and in Southern California seismic movement is one factor that may warrant closer evaluation. Unreinforced masonry chimneys are among the more shake-sensitive parts of a house, and the 1994 Northridge earthquake damaged chimneys widely across the region. That does not make every crack earthquake damage, and most are not. What it does mean is that cracking which appeared or widened after felt shaking is worth looking at rather than watching.

After an earthquake, look before the next fire. Shaking loads a masonry chimney hardest where it stops being braced by the house. That puts the damage in predictable places: the stack just above the roof line, where it sways on its own; the crown, which can crack through or slide on the brick below it; and the joint where the chimney meets the house wall, which opens as the stack pulls away.

Inside, clay flue tiles can crack or shift out of line at their joints, and none of that is visible from the street or the hearth. A stack that looks straight from the ground can still have loose top courses or a displaced liner. If bricks have come down or the chimney has visibly moved, keep the fireplace out of use and keep people clear of the area below the stack.

What follows depends on what is found. Displaced or loose masonry above the roof is usually a chimney rebuild question. Cracked or offset flue tiles are covered on chimney liner repair, and where the tile is past repair, relining the flue is the usual route back to a usable chimney.

Outside appearance is a poor guide to what is inside. Masonry can look sound with a damaged flue behind it, and a weathered chimney can have an intact one. A chimney tidied up at the exterior after a quake has not necessarily had anything else established about it.