Flexible Chimney Liner Installation

This page is about a material choice, not a separate service: when a flue needs a liner, should it be the flexible corrugated stainless tube or a rigid one? Flexible wins exactly when the geometry defeats rigid pipe — a chimney with an offset or 'dogleg,' an elbow at the smoke chamber, an out-of-round or shouldered clay tile, or a tight throat a stiff length can't be fed through. The corrugation lets the liner bend around the bends and compress through the pinch points while still sealing as one continuous channel. How this differs from the general relining page: relining is the decision to replace a failed liner and may end in flexible, rigid, or cast-in-place; this page is specifically the flexible option, chosen on geometry and appliance, whether the flue is being relined or lined for the first time.

Choosing flexible is a measurement before it is a purchase. We camera-scope the flue and map every offset, elbow, and dimensional pinch, then decide whether flexible is required (rigid won't pass) or simply preferred. Where rigid would pass a straight, accessible flue, we tell you so — rigid liner has smoother walls and marginally better draft, so we don't sell flexible by default. Where the throat is tight, we run an oval-profile flexible liner of equal cross-sectional area so it passes where a round one won't. The alloy still tracks the fuel — 316Ti stainless for wood, oil, coal, or high-sulfur fuels, 304 where the fuel allows — because a flexible liner of the wrong alloy corrodes exactly as fast as any other.

The flexible liner is also the natural match for appliance venting, which is much of why this type exists. Dropping a liner from a gas or wood fireplace insert down to the appliance collar almost always means negotiating the offset between the flue and the insert's outlet, and flexible makes that positive, full-length connection where rigid would bind — never a non-connected 'slammer.' Venting a stove or a high-efficiency appliance through an existing masonry chimney has the same geometry problem, and the flexible tube solves it. Because corrugation slightly slows draft and runs cooler, we add a liner-insulation wrap on solid-fuel and many appliance installs — it holds flue temperature up for draft, keeps creosote down, and maintains clearance to combustibles where the run passes near framing.

Installation is geometry-aware from top to bottom: we feed the liner from above, ease it through each offset rather than forcing it, insulate or pour-mix as required, and lock positive top-plate and appliance-collar connectors so the corrugated run is gas-tight end to end. Then we prove it — a smoke or draft check confirms the sealed path, and we document the UL-1777 listing for your records and any warranty, which on flexible liners is typically conditional on annual sweeping. How this differs from flue installation: that page often builds a brand-new, straight flue where a smooth clay or rigid run is the better first-time choice; flexible is the retrofit answer for an existing crooked flue rigid can't follow. The same scoping, alloy-matching, and insulation discipline governs every flexible-liner install across our national network.