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 Cap & Crown in Boulder: What to Know First
We provide independent Gelco chimney cap and crown service throughout Boulder, from the historic brick homes near Pearl Street to newer builds in Gunbarrel. Most Gelco cap replacements and crown repairs are completed in a single visit once we’ve run the camera and delivered your written price. You’ll see the photos before we quote a dollar, and we’ll never start work without a signed scope and warranty in hand.
This page is for Gelco owners who’ve noticed rust streaking down the flue, a cap that’s shifted after a windstorm, or crown cracking that’s letting water into the masonry. If you’re seeing any of that, call us at (970) 598-0453. Corrine Halstead and our crew have worked Gelco systems across Boulder County since 2009, and we keep common Gelco cap and crown parts on our trucks to avoid second trips.
How Gelco Products Fail - and How We Fix Them
- Gelco Ultra-Seal caps: mesh sag and frame twist. The 18/8 stainless mesh on Ultra-Seal multi-flue caps softens after repeated freeze-thaw cycles at Boulder’s 5,400-foot elevation. We’ve pulled dozens where the center mesh has dropped low enough to block draft. We replace with Gelco OEM mesh or upgrade to a heavier-gauge aftermarket equivalent, depending on flue configuration and your preference.
- Gelco single-flue caps: base-seal corrosion from snow load. The stamped steel base ring on standard Gelco single-flue caps traps meltwater against the flue tile. In Boulder’s dry winters, that water doesn’t evaporate quickly, it freezes in the shade of the cap and splits the seal. We remove the cap, inspect the flue tile for spalling, and reinstall with a silicone-composite base seal rated for our temperature swings.
- Gelco crown wash: hairline cracking at the bond line. Gelco’s pre-formed crown wash systems seal well when new, but the butyl tape bond to existing concrete degrades faster here than in humid climates. The dry air pulls moisture from the substrate, shrinking the concrete away from the tape. We strip the old wash, grind the concrete to 1/8-inch profile, and re-bond with a modified urethane that’s proven on Boulder chimneys through fifteen winter cycles.
- Gelco wind-load collars: fastener fatigue on exposed flues. The set-screw collars that secure Gelco caps to metal flues work loose where Boulder wind gusts hit 80-plus on the foothills. We’ve found collars backed out three full turns after a single spring storm. We replace factory set-screws with through-bolted stainless tabs, or spec a Gelco model with integrated bolt flanges if the flue wall thickness allows.
- Gelco multi-flue enclosures: corner seam separation. The spot-welded corners on older Gelco multi-flue enclosures fatigue from thermal cycling when one flue serves a wood burner and another sits cold. The differential expansion opens a gap that funnels water directly onto the smoke chamber. We weld-seam the corners or replace with a fully seam-welded aftermarket enclosure from our Haven buying network, whichever the camera shows is warranted.
Our Gelco Chimney Cap & Crown Process

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Call and schedule. A live person answers, checks our parts stock for your Gelco series, and books a window. You’ll get a text when your tech is en route.
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NFPA 211 Level 2 camera inspection. We run the camera down the flue before touching the cap or crown. Clause 4 of the Haven Standard requires a photo record on every job, and we need to see what’s below before we quote what’s above. The camera doesn’t guess. Neither do I.
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Written price, written scope, written warranty. We deliver all three before work starts. Haven Standard Clause 1: have it in writing. No exceptions, no “I’ll tell you when I’m done.”
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Parts decision: OEM Gelco or quality aftermarket. If your cap is under warranty, we use Gelco OEM and document the install for your claim. If it’s out of warranty, we quote both Gelco and equivalent aftermarket from our Haven network so you can choose.
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Repair or replacement with photo documentation. We photograph each step: the removed component, the substrate condition, the installed part, and the finished crown or cap from ground level and roof level.
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Final scan and 365-Day Done Right Promise. We run the camera once more to confirm no debris entered the flue during work. You get the photo record, the written warranty, and our promise: if it’s not done right, we make it right.
Before
AfterWhat Gelco Chimney Cap & Crown Costs in Boulder
| Service | Typical Range |
|---|---|
| Gelco single-flue cap replacement (OEM) | $340-$520 |
| Gelco multi-flue cap replacement (OEM) | $580-$890 |
| Gelco cap replacement (quality aftermarket) | $260-$440 |
| Crown repair with Gelco wash system | $720-$1,400 |
| Crown coating (minor cracking, no structural loss) | $480-$680 |
| Custom cap fabrication (non-standard flue) | $640-$1,100 |
What moves the price: flue height and roof pitch (scaffold or ladder work), whether the flue tile needs repair before the cap seats, and how far the crown crack has propagated into the brick below. We quote the full scope before we start, not a low opener with add-ons later.
Call (970) 598-0453 for a free estimate. We’ll run the camera, show you what we found, and give you a written price you can compare against any competitor’s quote. Our Free Second Opinion applies to any written estimate you bring us.
Why Boulder Homeowners Call Emberly Chimney Cleaners Boulder for Gelco Work

We’ve completed more than 38,000 chimney inspections and cleanings since 2009, every one with a written price before work started and a documented record when it was done. Corrine Halstead and our background-checked, uniformed technicians know Gelco products specifically, and we carry DuraFlex, HeatShield, and Haven-network aftermarket parts as backup when Gelco lead times stretch or when an upgrade makes more sense.
Our 365-Day Done Right Promise is stamped on every job. Calls are answered live, 24/7, by a person who can check parts stock and book your visit. You’ll get a text when your tech is on the way, and you’ll see the camera footage yourself before any number is quoted.
FAQs
No, installing a Gelco cap yourself or hiring an independent technician does not void the product warranty, provided the installation follows Gelco’s specifications and the claim is documented. We photograph every Gelco install per Haven Standard Clause 4 and keep records you can submit with any warranty claim. Call (970) 598-0453 if you need help with documentation.
A properly installed Gelco stainless cap typically lasts 12-18 years in Boulder, but the 5,400-foot elevation and intense UV at this altitude can shorten the lifespan of powder-coated models to 8-12 years. We inspect the mesh and base seal annually as part of our sweep service and flag replacement before failure. Call (970) 598-0453 to schedule a camera inspection.
We can recoat a Gelco crown if the underlying concrete is sound and cracking is limited to the surface layer, which we confirm with a hammer test and camera inspection of the interior masonry. If the crack has opened to the flue liner or the concrete is spalling, we recommend full crown rebuild with a Gelco wash system or poured concrete cap. Call (970) 598-0453 for a free evaluation.
We stock common Gelco single-flue and multi-flue caps, base seals, and wind-load collars on our Boulder trucks. Specialty sizes or custom colors typically arrive within three business days through our Haven buying network. We’ll tell you exactly what’s in stock when you call (970) 598-0453 so you’re not booking time off work for a return trip.
The cap may be shedding water outward while the crown beneath it has cracked, or the flue tile may have shifted, opening a gap the cap can’t cover. We see this often in Boulder homes built between 2015 and 2020 where rapid framing settlement stressed the chimney structure. The camera shows the real path. Call (970) 598-0453 and we’ll trace it with you on the screen before quoting any work.
Written by Corrine Halstead, Owner, Emberly Chimney Cleaners Boulder at Emberly Chimney Cleaners Boulder, serving Boulder and nearby areas.





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