Chimney Relining — Stainless, Cast-in-Place and Joint Sealing

The flue liner is the inner surface of the chimney — the pipe inside the pipe. On almost every masonry chimney in Los Angeles it is a stack of clay tiles, each about two feet long, mortared together from the smoke chamber to the top. Its job is to contain the combustion products and keep them away from the masonry and the wood framing around it, and to give the smoke a smooth surface to travel up so the chimney drafts properly.

When a liner fails, the failure is almost always at the mortar joints between tiles rather than through the tile itself. The joint opens, and combustion gases — which include carbon monoxide — now have a path into the masonry and from there into wall cavities and rooms. Heat also reaches the structural brick and, in older construction, framing that was built with inadequate clearance to begin with. This is the mechanism behind most chimney-related house fires that are not caused by creosote directly.

Clay tile fails for three reasons here, and usually more than one at once. Age is the first: the material has a design service life of roughly fifty to seventy years and the great majority of our housing stock is older than that. Seismic movement is the second, and the 1994 Northridge earthquake cracked tile across the whole Valley in a way that is invisible without a camera. The third is a chimney fire, which can crack a liner in a single event through thermal shock — even a small fire that appeared to put itself out.

Relining replaces that failed inner surface without rebuilding the chimney. It is substantial work and it is not cheap, and we would rather be straight about that than quote low and add later. But it is also the difference between a chimney you can safely use and one you cannot, and it is considerably less than a rebuild. Call (818) 536-7759 and we will tell you honestly whether yours needs it.

A large and growing share of our relining work is driven by gas conversion rather than by damage. People convert for good reasons — convenience, air quality, and the fact that during a no-burn day under South Coast AQMD rules a gas appliance can be used when a wood fire cannot. But a conversion is not simply a matter of installing an appliance in the existing opening, and this is where a lot of money gets wasted.

The issue is flue sizing. A masonry flue built for an open wood-burning fireplace is enormous relative to what a sealed gas appliance needs. A gas insert or a direct-vent unit produces far less volume of much cooler exhaust, and in an oversized flue that exhaust cools further, slows down, and fails to establish a draft — which means combustion products can spill into the room. The code requirement for a correctly sized liner on a gas appliance exists for exactly this reason, and NFPA 211 requires a Level 2 inspection on any change of fuel type.

Practically, a wood-to-gas conversion on a Los Angeles masonry chimney almost always means a stainless liner sized to the new appliance, run the full height and sealed at both ends. That is from $1,200 and it is not an optional extra that an installer can skip to come in cheaper. If you have been quoted a gas insert installation with no liner, ask the question, because the alternative is an appliance that may not vent safely.

We do the liner work and coordinate with the appliance installer rather than selling you the appliance, which means we have no reason to recommend one unit over another. Call and tell us what you are planning and we will tell you what the chimney needs for it.