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.
Before
After
Before
After
Before
AfterDuraFlex Chimney Cap Installation: The Boulder Owner’s Guide
We stock and install DuraFlex-compatible chimney caps across Boulder, with most jobs running $340-$580 installed depending on flue diameter and whether your crown needs sealing work. Same-day installation is available when we have your diameter in stock, which covers most DuraFlex 5.5-inch through 8-inch round liners common in Boulder County. Homeowners usually discover the cap has failed after finding rust flakes in the firebox, hearing water drip behind the damper during spring snowmelt, or noticing the mesh has pulled away from the collar after a windstorm off the Flatirons.
Which DuraFlex Models This Applies To
DuraFlex produces several liner series, and the cap you need depends on which one is running up your flue. The DuraFlex SW (stainless wall) and DuraFlex HT (high-temperature) lines both use round termination caps with band-clamp or draw-band attachment, but the collar depth and mesh spec differ. SW caps carry a 304-alloy mesh; HT caps use 316Ti for the higher heat loads of wood-pellet and EPA-certified stoves. The label is stamped on the liner itself, usually visible from the firebox throat with a flashlight.
If the label’s worn off, measure the liner outer diameter at the top of the flue, not the inner dimension. A 6-inch liner measures roughly 6.75 inches OD with the insulation wrap. We source caps through Haven’s buying network from DuraFlex, Olympia Chimney, and Famco, and we’ll match OEM spec unless an aftermarket equivalent meets the same alloy grade at lower cost. That’s a written comparison, not a verbal upsell. Emberly Chimney Cleaners Boulder is an independent service provider with no affiliation to DuraFlex.
Signs Your DuraFlex Chimney Cap Installation Is Failing
- Rust staining on the exterior masonry below the crown. DuraFlex caps use stainless collars, but the mesh and lid are spot-welded at stress points. In Boulder’s dry climate with sudden temperature swings, those welds fatigue faster than in humid regions. The rust you see is often the lid seam failing, not the liner itself.
- Water in the firebox after snow or hard rain. The cap’s overhang is designed to shed water beyond the flue edge. When the lid warps from thermal cycling or the mesh pulls the collar out of round, water tracks directly down the liner. In older Mapleton Hill homes with shallow fireboxes, this pools on the smoke shelf and saturates the facing brick.
- Downdraft smoke or odor even with the damper open. The mesh on a DuraFlex cap serves as a spark arrestor and wind baffle. Once the mesh corrodes through or detaches, wind coming off the foothills can press straight down the flue. You’ll notice this most on west-facing chimneys during winter upslope events.
- Animals or debris in the flue. Squirrels and raccoons in the Chautauqua and Martin Acres areas have no trouble exploiting a gap where the mesh has separated from the collar. A proper cap mesh has 5/8-inch openings; anything larger or torn is a failed cap.
- The cap is visibly tilted or missing after a wind event. DuraFlex caps secure with a stainless draw-band tightened around the liner top. If the band was under-torqued or the liner top was out-of-round during original installation, the cap lifts in sustained winds above 50 mph, which Boulder sees several times each winter.
BeforeAfterReplacement Cost & What’s Included
| Scope | Price Range |
|---|---|
| DuraFlex cap replacement, standard 5.5″-6″ liner, band-clamp style | $340-$420 |
| DuraFlex cap replacement, 7″-8″ liner or HT-series with 316Ti mesh | $420-$520 |
| Cap plus crown seal (minor cracks, silicone-based sealant) | $480-$580 |
| Cap plus crown rebuild or pour (spalling, structural cracks) | $680-$1,200+ |
Every installation includes the cap, draw-band or clamp hardware, a fresh bead of high-temp sealant at the liner-to-cap joint, and a camera scan down the flue to confirm no debris or moisture damage below. We deliver a written price before work starts, a photo record of the installed cap and flue condition, and a 365-Day Done Right Promise backed by Haven Standard Clause 1. The range widens with liner diameter and crown condition, not with how busy we are.
DIY or Call Us?
An owner can safely check whether the cap is present, whether it’s sitting level, and whether the mesh has obvious gaps. Use binoculars from the ground; don’t climb the roof. The danger isn’t the cap itself, it’s the roof pitch and the fact that most Boulder chimneys sit above two stories with the foothills wind already working against you.
Where DIY goes wrong: draw-band torque specs matter. Under-tighten and the cap lifts in the next windstorm. Over-torque and you oval the liner top, which means the next cap won’t seat properly either. We torque to DuraFlex spec with a calibrated banding tool, then camera-scan to confirm the liner interior wasn’t deformed. The camera doesn’t guess. Neither do I.
Call (970) 598-0453 for a written estimate. We’ll confirm your liner series and diameter, check stock, and book the install.
FAQs
Expect 12-18 years for a 304-alloy cap in Boulder’s dry climate, or 15-22 years for 316Ti if you’re burning seasoned hardwood and not over-firing. The weld points at the mesh-to-collar joint usually fail first, accelerated by our UV exposure at 5,400 feet and the thermal shock of cold starts after overnight lows below 20°F. Call (970) 598-0453 and we’ll camera-inspect to tell you where yours stands.
Mesh re-welding and collar straightening are possible, but rarely cost-effective. By the time the mesh has torn or the lid has warped, the alloy has work-hardened at the failure point; a repair lasts 2-4 years versus a full replacement at 12-plus. We don’t quote repairs that we wouldn’t accept on our own chimney. Call (970) 598-0453 for a free second opinion on any repair estimate you’ve already received.
Most DuraFlex cap replacements run 45-90 minutes on site, including the camera scan and documentation. If we need to order a non-standard diameter or HT-series cap, lead time is 3-5 business days through Haven’s buying network. We text when the part arrives and when the tech is en route.
We carry 5.5-inch, 6-inch, and 7-inch caps for both SW and HT series on every Boulder service vehicle. The 8-inch and oval adapters are warehouse-stocked locally and available same-day with morning notice. We verify your diameter before dispatch so we’re not guessing in your driveway.
Written by Corrine Halstead, Owner, Emberly Chimney Cleaners Boulder at Emberly Chimney Cleaners Boulder, serving Boulder and nearby areas.