DuraFlex Flue Liner Replacement Nationwide

DuraFlex Flue Liner Replacement: The Miami Owner’s Guide

DuraFlex flue liner replacement in Miami typically runs $1,800 – $3,400 installed, depending on the liner diameter, height of the chimney, and whether the existing liner can be pulled free or needs to be broken out. We keep common DuraFlex-compatible liner sizes on our trucks, so many replacements can be completed the same day we diagnose the failure. Most owners discover the problem during a routine sweep or inspection when we find rust-through, a split seam, or delamination on the inner liner wall.

Call (786) 305-7861

DuraFlex is a flexible stainless steel liner system used to reline masonry chimneys. It is common in older Miami homes, especially in Coral Gables, Coconut Grove, and the 1950s ranch neighborhoods west of the Palmetto. The liner’s job is simple: it carries hot flue gases and creosote out of the house without letting either touch the masonry around it. When the liner fails, the masonry absorbs the damage instead. In Miami’s salt air and summer humidity, that failure happens faster than most owners expect.

Which DuraFlex Models This Applies To

DuraFlex is manufactured by DuraVent and sold in two main series: DuraFlex 304 and DuraFlex 316. The 304 series is the standard stainless liner used for wood-burning fireplaces and stoves. The 316 series is a higher-grade alloy used for oil-fired appliances and some gas applications where condensate is more acidic. The model matters because the replacement section or full reline must match the alloy rating of the original install. Mismatching a 316 appliance with a 304 liner is a code violation and will void the manufacturer’s rating.

The liner sections are marked along the outer jacket with the model, diameter, and alloy grade. If the existing liner is buried in masonry and the label is gone, we measure the inside diameter with a caliper and verify the appliance type to determine what belongs. DuraFlex liners come in standard diameters from 4 inches up to 8 inches, but most Chicago-style masonry fireplaces in Miami that were retrofitted in the 1990s and 2000s used 6-inch liners. We stock 6-inch DuraFlex-compatible sections and can source larger or smaller within a day or two.

For replacement sections, we use genuine DuraFlex components when available. For full relines where the original liner is too far gone to patch, we also work with HeatShield and Gelco products where the application calls for them. Flint Chimney Co Miami is an independent service provider and is not affiliated with DuraFlex or DuraVent.

Signs Your DuraFlex Flue Liner Replacement Is Failing

• Rust flakes or pinholes on the liner surface. Miami’s humidity works on stainless steel differently than dry climates. The outer jacket of a DuraFlex liner can show surface rust while the inner wall is still intact. That is a warning sign, not a failure. We check for pinholes with a light test before recommending replacement.
• Water in the firebox after rain. A failed liner seam lets water through the flue and into the firebox. In Miami’s afternoon deluges, this shows up fast. The brown staining on the firebrick is what owners notice first.
• A rusted or detached top plate at the chimney crown. The top plate seals the liner to the flue tile. Salt air eats the fasteners and the plate edge. When the plate lifts, the liner can shift and the seam can separate one or two feet down from the top.
• Smoke smell inside the house when the fireplace is not in use. A compromised liner lets flue gas back into the chimney cavity instead of out the top. On humid Miami days, that stale smoke smell gets pushed into the house by the pressure difference.
• White or brown crust on the exterior chimney brick. Creosote-laden moisture seeping through the masonry shows up as efflorescence or staining on the outside face of the chimney. By the time this is visible from the ground, the liner has been leaking for a while.

Replacement Cost & What’s Included

A full DuraFlex flue liner replacement in Miami runs $1,800 – $3,400 installed. A partial section replacement, where the lower portion is intact and only the top 5 to 10 feet has failed, runs $700 – $1,400. A repair of a top plate and reattachment alone can run $350 – $600. The big driver is access: a one-story chimney with a walkable roof is fast. A three-story chimney on a Brickell condo-era building with a steep pitch and no roof access is a different job entirely.

Every quote from us includes the liner material, the top plate, the connector at the appliance, the labor, and the haul-away of the old liner. We do not quote a part price and then surprise you with labor. The written price you approve is the final price. If we open the chimney and find additional damage we could not see from the top or the firebox, we stop, show you what we found, and get your written approval before any additional work starts. That is how we have operated since 2002.

Every DuraFlex liner replacement we install carries the 365-Day Done Right Promise in writing: if the repair fails within one full year, we return at no charge and make it right. No pro-rated coverage, no argument about whether it was “our fault.” The guarantee is on the invoice, signed.

DIY or Call Us?

You can safely do a few checks yourself. Look at the top plate from a ladder if your roof is walkable and you are comfortable on it. Look at the firebox for staining. Shine a flashlight up the flue and look for rust streaks or separated seams at the bottom. Report what you see. Tell me what you saw, I’ll tell you what it costs.

What you should not do is pull a failed liner yourself. These liners are attached to the appliance connector and the top plate under tension. When a corroded seam lets go, the section above can drop unexpectedly. A falling liner section inside a masonry flue can wedge, twist, and become impossible to remove without a lift and a masonry opening. It also means working at roof height around an open flue, which is where we see serious falls in this trade. A failed DuraFlex liner is a repair for a trained chimney technician with the right rigging. Call (786) 305-7861 and we will get it done without turning your chimney into a construction project.

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