DuraFlex Flue Liner Replacement Nationwide

DuraFlex Flue Liner Replacement: The San Francisco Owner’s Guide

If your DuraFlex flue liner has cracked, separated, or corroded through, the fix in San Francisco typically runs $1,800 to $3,400 installed, depending on liner diameter, run length, and roof access. We keep DuraFlex-compatible liner sections and connectors on our trucks for most two-story homes in the Sunset, Richmond, Noe Valley, and Bernal Heights, so we can often complete the swap in a single visit once we’ve confirmed measurements. The most common way owners discover a failed liner is not smoke in the living room, but a chimney inspection that turns up rust flakes at the base and a camera image showing a split seam or pinhole corrosion midway up the flue.

Call (831) 534-3789

DuraFlex liners are double-wall, flexible aluminum systems that rely on a continuous inner wall to keep combustion gases inside the flue. When that inner wall fails anywhere along its length, the liner is no longer doing its job, and the fix is almost always full replacement of the damaged section or the entire run, not patching.

Which DuraFlex Models This Applies To

The DuraFlex product line includes several series: DuraFlex 316, DuraFlex AL (aluminum), and DuraFlex Smooth Wall. The 316 series is the one we install most often in San Francisco because it is rated for both wood and gas appliances and holds up better against the moist coastal air that accelerates corrosion in lesser alloys. The AL series is lower cost but only appropriate for gas, never wood, and we rarely recommend it in this climate because the salt-fog exposure from the Pacific shortens an aluminum liner’s life measurably.

Identifying your exact liner diameter is the single most important step before quoting a replacement. DuraFlex liners are sized by the inner diameter in inches, typically 4, 5, 5.5, 6, or 8 inches for residential applications, and the size is printed on the liner’s outer jacket every few feet. If that label has worn away, we measure the existing liner with a set of diameter gauges at the top of the chimney, not at the appliance connection, because liner diameters sometimes change where a connector was forced onto an undersized section. A liner that was 6 inches at the appliance can neck down to a patched 5.5-inch section mid-run in older installations, and that is a compatibility gotcha that causes ordering errors if you only measure at one point.

As an independent chimney service company, Alcott Chimney San Francisco is not affiliated with DuraFlex or its parent, but we install and service genuine DuraFlex components alongside equivalent professional trade brands. For this application, we source factory-specified sizing rather than aftermarket generics because a quarter-inch diameter mismatch at a connector is enough to create a leak path.

Signs Your DuraFlex Flue Liner Replacement Is Failing

• Rust flakes or dark grit collecting at the cleanout door. This is the inner liner wall shedding material. Aluminum and stainless liners don’t flake when healthy. Once you see shiny metal fragments or brown dust at the base, the liner is actively corroding.
• A metallic rattling or popping sound during heating cycles. As the liner expands against moisture-swollen masonry or a shifting flue tile, the seam can lift. That sound often means the liner is already separated inside the chimney, not just expanding.
• Faint smoke smell inside the house with the damper open. Combustion gas is finding a gap between liner sections and traveling into the chimney chase or wall cavity. This is a call-us-today symptom, not a check-it-again-next-week symptom.
• Visible staining on the ceiling near the chimney chase. Water and acidic flue gases escaping the liner condense on framing. Stains near a chimney that used to be dry are a sign the liner has been compromised for weeks or months, not days.
• An inspection camera shows dark streaks, dimpling, or a separated seam. We show every customer the camera footage before we recommend anything. If you can see the seam opening more than a few millimeters, that liner is done, and burying it beneath a new cap or new crown will not save it.

Replacement Cost & What’s Included

A full DuraFlex flue liner replacement in San Francisco generally lands between $1,800 and $3,400, and the spread is driven by three things: how tall your chimney is, whether we need scaffolding or a roof anchor system for a steep-pitch Victorian near Alamo Square or Potrero Hill, and whether the old liner comes out cleanly or is fused with creosote and tar. The liner material itself is typically $25 to $45 per foot depending on diameter, and a standard two-story chimney takes 25 to 40 feet of liner. Labor, connectors, a new top plate, rain cap, and reconnection to the appliance make up the rest.

Before any work starts, we hand you a written price that includes the exact liner size, footage, and fittings. No allowance-line surprises at the end. And every DuraFlex liner replacement we install carries our written guarantee: if the repair fails within the coverage period, the second visit and the corrective work are free. That guarantee travels with the job, not just the invoice.

DIY or Call Us?

There are exactly two things a homeowner can safely do before calling us. First, open the cleanout door at the base of the chimney and look for rust flakes or metallic grit. Second, shine a flashlight up the flue from the firebox with the damper fully open and look for any obvious gap, sag, or separated seam within the first few feet. That is where your involvement ends, and it should. Pulling a 30-foot flexible liner up through a chimney that often has offset clay tiles mid-run is a two-person job that can turn bad fast. If the liner snags on a shifted tile and you yank it free, you can dislodge the tile itself, collapse a section of flue, and turn a $2,000 liner replacement into a full rebuild. Liner work is not like swapping a faucet. We do it with a drop cone, a pulling winch, and a spotter on the roof. Call (831) 534-3789 and tell us what you’re seeing. We’ll tell you straight what it means.

FAQs