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.
DuraFlex Chimney Cap & Crown in Ashburn: What to Know First
We provide independent DuraFlex chimney cap and crown service across Ashburn, from the established neighborhoods near One Loudoun to newer construction along Loudoun County Parkway. Most DuraFlex cap replacements and crown repairs are completed in a single visit, with upfront pricing agreed before we start. We don’t sell what you don’t need, and we don’t start work until you’ve seen the camera footage and understand what we’re proposing.
This page is for homeowners who already have a DuraFlex liner, cap, or crown component and need honest guidance on whether it can be repaired, what it should cost, and who in Ashburn actually knows these parts. If you’re seeing rust streaks, mortar crumbs in the firebox, or water staining on the ceiling below the chimney, call us at (571) 701-8135. A live person answers, 24 hours a day.
How DuraFlex Products Fail - and How We Fix Them
- DuraFlex SW factory-built caps corrode at the seam welds. The 304-alloy shell holds up well in Ashburn’s freeze-thaw cycles, but the stamped seam where the lid meets the skirt eventually weeps. We see this most on units installed 12 to 18 years ago. We replace with a Gelco or Olympia Chimney multi-flue cap that overlaps the flue tile properly, or source a DuraFlex-compatible OEM cap when the flue configuration demands it.
- DuraFlex Pro liner top plates warp from thermal cycling. The Pro series uses a heavier gauge, but the top plate still bellies upward after years of expansion and contraction. That gap between plate and flue tile lets rain run straight down the liner. We pull the plate, inspect the liner termination for creosote buildup, and reinstall with a properly sized cap that accounts for the new thermal profile.
- DuraFlex crown coatings crack at the liner penetration. The factory refractory crown coating shrinks away from the stainless collar. In Ashburn, where summer humidity follows hard winter freezes, that crack widens fast. We grind back to sound concrete, apply a new sloped crown with proper drip edges, and seal the penetration with a high-temp silicone rated for the Pro or SW temperature range.
- DuraFlex DW double-wall caps lose their internal insulation. The air gap fills with condensation debris, and the cap’s weight drops onto the storm collar. We see this on taller Ashburn chimneys where the cap sits in heavier wind exposure. We replace with a properly weighted Gelco or Famco cap, or rebuild the storm collar assembly if the liner itself is still sound.
- DuraFlex light-wall caps on oil-to-gas conversions sit too low. When Ashburn homeowners converted from oil to gas in the 1990s and 2000s, many caps were never raised for the lower exhaust temperature. The result is chronic downdraft and moisture trapping. We measure the new BTU output, calculate proper cap height, and install a vented cap that matches the appliance, not the old fuel type.
Our DuraFlex Chimney Cap & Crown Process
- 1
Call and schedule. A live person answers, day or night. We book a Level-2 camera inspection with photo documentation.
- 2
On-site diagnosis. Our technician runs a camera up the flue, photographs the cap, crown, and liner termination from inside and out, and explains what we’re seeing in plain English.
- 3
Parts decision. We check DuraFlex OEM availability against quality aftermarket options from Gelco, Olympia Chimney, or Famco. We recommend what fits your flue and your budget, not what pads our margin.
- 4
Upfront pricing. You get one number. That’s the number on the invoice. No surprises.
- 5
The repair. Background-checked, uniformed techs complete most DuraFlex cap and crown jobs in a single visit. Mortar cures, coatings set, and we test draft and cap fit before we leave.
- 6
Documentation and guarantee. You receive photos, a written verdict, and our 90-Day Done Right Promise - in writing, no arguing. If it’s not right, we come back.
What DuraFlex Chimney Cap & Crown Costs in Ashburn
| Service | Typical Range | What Moves the Price |
|---|---|---|
| DuraFlex cap replacement (standard single-flue) | $340 - $580 | Flue tile condition, access height, OEM vs. aftermarket cap |
| DuraFlex multi-flue cap installation | $520 - $890 | Flue spacing, custom screening, wind rating for exposed Ashburn lots |
| Crown repair with DuraFlex liner penetration seal | $680 - $1,240 | Crown size, degree of concrete spalling, need for form-and-pour vs. coating |
| Crown coating (sound substrate, DuraFlex collar reseal) | $420 - $650 | Number of cracks, accessibility, whether the storm collar needs replacement |
Every estimate is free. We don’t charge to look, and we don’t pressure you to decide on the spot. Some crowns can wait a season. Others shouldn’t. The camera tells the truth, and we’ll show you exactly what it sees. Call (571) 701-8135 for an exact quote.
Why Ashburn Homeowners Call Hearthstone Chimney Co. for DuraFlex Work
We’ve been sweeping and repairing chimneys across Ashburn for well over a decade. Russell Haines learned this trade at Los Angeles Trade-Technical College, and he’s run crews through everything from the older colonials near One Loudoun to new builds going up along Loudoun County Parkway. The flue doesn’t lie - and neither do we.
Our 90-Day Done Right Promise means if the cap leaks or the crown cracks after we leave, we come back. No paperwork to dig up, no argument about whether it was pre-existing. We also work with HeatShield and Gelco when a DuraFlex component has been discontinued or when a different brand simply fits the repair better. Photos you can see. A plain-English verdict. A square deal on the bill. That’s the Keystone Standard we’ve kept for over 42 years.
FAQs
No, provided the work is done with DuraFlex-compatible parts and proper termination clearances. As an independent DuraFlex service provider, we follow manufacturer specifications for flue sizing, cap overhang, and storm collar placement. We document our work with photos in case you ever need to reference it. Call (571) 701-8135 if you’d like us to review your specific DuraFlex series and warranty status.
Most are completed in two to four hours, including inspection, removal, and testing. Multi-flue caps or jobs requiring storm collar rebuilds may run longer. We complete most jobs in a single visit. You’ll know the time estimate before we start.
Yes, though some SW-series caps have been superseded by newer designs. We stock quality aftermarket caps from Gelco and Olympia Chimney that mate correctly with SW flue tiles, and we can fabricate custom transitions when the original part is no longer produced. We never substitute a generic cap that doesn’t fit the thermal or draft requirements.
We grind-test the surface during inspection. If the concrete is sound beneath the top quarter-inch, a crown coating with proper slope and drip edges usually suffices. If we tap through to crumbly aggregate or find the liner penetration has shifted, we recommend a formed replacement. You’ll see the camera footage and the tap test results before we recommend either.
In Ashburn’s climate, freeze-thaw cycles open cracks wider each winter, and summer humidity drives moisture into the liner cavity. A cracked crown can damage the DuraFlex liner itself, turning a $600 repair into a $2,400+ liner replacement. That said, not every crack is urgent. We rate crown conditions during inspection and tell you honestly whether it can wait. Call (571) 701-8135 for a free look.
Written by Russell Haines, Owner & Master Sweep, Hearthstone Chimney Co. at Hearthstone Chimney Co., serving Ashburn and nearby areas.





Before
After
Before
After
Before
After