Level 1 sweep and inspection to the NFPA 211 annual standard - flue, crown, cap, and flashing checked and photographed
Chimney sweep logs do not sweep chimneys. They loosen some creosote - which then falls where a brush and vacuum still have to collect it.
Gelco Chimney Liner & Rebuild in Denver: What to Know First
We provide independent Gelco chimney liner and rebuild service across Denver, typically quoting jobs within 24 hours of your call and completing most liner replacements in one to two days. As an independent Gelco service provider, we’re not bound to factory-only parts, which means we can source Gelco UL-1777 listed stainless steel, match OEM flue diameters, or cross-reference to DuraFlex or HeatShield when the job calls for it. Every quote arrives in writing before work starts, with a camera-scan inspection and photo record included, so you see what we see before deciding.
This page is for Denver homeowners who know they’ve got a Gelco liner or are weighing a rebuild and want the actual price range, not a phone tag exercise. If that’s you, call us at (720) 674-7312 or read on.
How Gelco Products Fail - and How We Fix Them
- Gelco ProFlex flexible liner fatigue at termination. The ProFlex series uses a corrugated 316Ti stainless body that handles thermal cycling well, but we’ve found the upper termination collar can work-harden after 8-12 years in Denver’s freeze-thaw cycles, developing circumferential cracks right where the cap meets the flue. We cut back to sound metal, weld a new Gelco-compatible termination collar, and pressure-test the joint rather than replacing the entire run.
- Gelco rigid liner joint separation in tall Denver flues. The Gelco rigid 304/316 system with twist-lock couplers performs well in standard two-story homes, but in Denver’s pre-war bungalows with 35-foot-plus masonry flues, thermal expansion can loosen couplers that weren’t back-tightened to spec. We find this most often in Capitol Hill and Baker basements. Our fix: drop a camera, locate the separated joint, and either re-seat with Gelco’s high-temp sealant or transition to a DuraFlex continuous flex liner if the joint pattern is repeating.
- Smoke chamber parging failure above Gelco inserts. Gelco’s fireplace inserts vent into a stainless liner, but the smoke chamber (the inverted funnel above the firebox) is often original parged brick. When that parging flakes off, the insert’s exhaust velocity pulls debris into the liner throat. We see this in Park Hill Victorians where the original 1920s parging meets a 2010s Gelco insert. We re-parge with Chamber-Tech 2000 or HeatShield Cerfractory foam, then verify clearances with a borescope.
- Gelco liner oversizing in converted coal flues. Denver’s older neighborhoods, especially along Federal Boulevard and in Berkeley, have 8×12 or larger coal-era flues where a previous installer dropped a 6-inch Gelco liner and called it done. The excess annular space fills with deteriorated mortar, creating a secondary flue that bypasses the liner. We extract the old liner, remove the debris, and install an insulated Gelco or Olympia Chimney liner with proper pack-out to eliminate the void.
- Crown wash failure sending water down Gelco liner walls. Gelco stainless resists internal corrosion, but Denver’s spring hail and UV-degraded crown wash can funnel water between the liner and clay tile, accelerating exterior rust at the first joint below the roofline. We repair the crown with a poured concrete crown or Gelco’s stainless chase cover, then inspect the liner exterior with a mirror and light, replacing only the damaged section rather than the full run.
Our Gelco Chimney Liner & Rebuild Process

- 1
Camera-scan inspection (NFPA 211 Level 2). Corrine Halstead or a named technician drops a 360-degree camera the full flue length. We document liner condition, joint integrity, creosote class, and any spalling or gaps in the surrounding masonry. You get the footage before we talk price.
- 2
Written scope and price. We specify Gelco OEM versus DuraFlex or HeatShield alternatives, explain why one fits your flue better, and itemize liner, labor, materials, and permit if Denver requires it for your neighborhood. No work starts until you have this in hand.
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Parts procurement through Haven’s buying network. We source Gelco UL-1777 listed stainless, flexible, or rigid components, or cross-reference to HeatShield’s cerfractory resurfacing system or DuraFlex’s continuous flex when the flue geometry demands it. Materials procured through our network to keep customer prices honest.
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Installation or rebuild. For liner replacement, we pull the old run, size the new one to appliance BTU and flue diameter per IRC Chapter 10, and secure at the termination. For partial or full rebuilds, we rebuild to current Denver building code with proper clearance to combustibles.
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Smoke test and final camera pass. We run a smoke pellet or blower door-assisted draft test, then camera the finished job. The photo record, written warranty, and 365-Day Done Right Promise documentation are delivered before we leave.
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Cleanup and archive. Your documented photo record goes into our archive, continuous since 2009, under Haven Standard Clause 4. The camera doesn’t guess. Neither do we.
Before
AfterWhat Gelco Chimney Liner & Rebuild Costs in Denver
| Service | Typical Range | What Moves the Price |
|---|---|---|
| Gelco stainless liner replacement (single flue, standard height) | $2,800 - $4,200 | Flue length, diameter, insulation requirement, access difficulty |
| Gelco flexible liner with insulation pack-out | $3,200 - $4,800 | Offset flues, chimney height above 25 feet, need for new termination |
| Partial chimney rebuild (above roofline, with Gelco liner) | $4,500 - $7,500 | Courses to rebuild, crown replacement, scaffolding needs |
| Full chimney rebuild with new Gelco liner system | $8,500 - $14,000 | Foundation to cap, number of flues, hearth reconstruction |
| Gelco liner repair (sectional replacement, joint repair) | $1,200 - $2,400 | Location of damage, accessibility, single versus multiple joints |
These are real ranges for Denver’s market, accounting for labor rates, permit costs in Denver County, and the freeze-thaw wear we see on local masonry. The only way to pin your number is to camera the flue and see what’s there. Call (720) 674-7312 for a free estimate - estimates are free, and we deliver them in writing.
Why Denver Homeowners Call Level Two Chimney Denver for Gelco Work

We’ve inspected and cleaned more than 38,000 chimneys since 2009, every one with a written price before work started and a documented record when finished. Our technicians are background-checked, uniformed, and assigned by name - you’ll get a text when yours is on the way. We carry Gelco, DuraFlex, HeatShield, Olympia Chimney, Famco, and Copperfield materials, so we’re not forcing a brand that doesn’t fit your flue.
The 365-Day Done Right Promise covers every job: if it’s not done right, we make it right. And our Free Second Opinion on Any Written Estimate means you can bring us a competitor’s quote and we’ll tell you straight whether the scope and price hold up. Live phone support runs 24 hours a day, 7 days a week - a real person, not a voicemail tree.
FAQs
No - if the repair uses Gelco UL-1777 listed components and follows manufacturer clearances, the warranty remains intact. As an independent Gelco service provider, we document every part number and installation detail so you have proof if a claim ever arises. Call (720) 674-7312 for an exact quote - estimates are free.
Yes. Gelco’s rigid and flexible liner components have stayed dimensionally consistent for decades, and our Haven buying network stocks common diameters from 3 to 8 inches. For discontinued series, we cross-reference to DuraFlex or Olympia Chimney with matching UL listings and thermal ratings. Call (720) 674-7312 for an exact quote - estimates are free.
We camera the flue and show you. A single failed joint or localized corrosion spot often just needs sectional repair. Multiple joint separations, exterior rust bleeding through the liner wall, or a liner that’s pulled away from the appliance collar usually means full replacement. Nothing is recommended without camera evidence you can see for yourself. Call (720) 674-7312 for an exact quote - estimates are free.
Most Gelco liner replacements in Denver are completed in one to two days, depending on flue height, roof access, and whether we’re also rebuilding the crown or smoke chamber. We book by the job, not the hour, and we don’t start until you’ve approved the written scope. Call (720) 674-7312 for an exact quote - estimates are free.
An unlined or failed liner lets combustion gases, including carbon monoxide, leak into wall cavities and living spaces. It also allows creosote to build on combustible framing, which is how chimney fires start. In Denver’s dry winters, that risk runs higher because homeowners run appliances harder and longer. The camera footage tells us whether your liner is holding or failing - no guesswork, no scare tactics. Call (720) 674-7312 for an exact quote - estimates are free.
Written by Corrine Halstead, Owner, Level Two Chimney Denver at Level Two Chimney Denver, serving Denver and nearby areas.





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