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 Crown Repair: The Crystal Lake Owner’s Guide
DuraFlex crown repair in Crystal Lake typically runs $340-$620 installed, depending on whether we’re sealing surface cracks or replacing the full crown assembly. We stock DuraFlex-compatible crown components on our trucks and can usually complete the repair in a single visit once we’ve camera-scanned the flue to confirm the damage hasn’t reached the liner below. Most Crystal Lake homeowners discover the problem during their pre-burning-season sweep, or after spotting fresh masonry debris on the roof or water staining on the ceiling near the chimney breast.
Which DuraFlex Models This Applies To
DuraFlex crowns are found on two distinct product lines, and mixing them up is the most common ordering mistake we see in McHenry County.
The DuraFlexSS series uses a stainless steel outer shell with a cast refractory crown cap. Look for the stamped “DFSS” prefix on the data plate, usually mounted on the outer collar near the flue termination. These crowns measure 13″ × 13″ or 13″ × 17″ for standard residential installations, with a 2″ minimum overhang specified by DuraFlex’s installation manual.
The DuraFlexHT high-temp series uses a thicker refractory crown with integrated venting channels. The data plate reads “DFHT” and the crown assembly is heavier, typically 18-22 lbs versus 12-15 lbs for the SS equivalent. The bolt pattern differs too: SS crowns use four corner bolts on 11″ centers, while HT crowns use six bolts on a 9.5″ × 13″ pattern.
We source DuraFlex OEM crowns through our Haven buying network, though we also carry compatible refractory crowns from Olympia Chimney for homeowners whose original DuraFlex crown has been discontinued. The Olympia equivalent matches the thermal expansion coefficient but uses a slightly different gasket profile, so we always verify fit with a dry assembly before sealing. Level Two Chimney Crystal Lake is an independent service provider, not affiliated with DuraFlex.
If you’re unsure which series you have, text us a photo of the data plate. We’ll identify it before we dispatch.
Signs Your DuraFlex Crown Repair Is Failing

- Hairline cracks radiating from the flue opening. These start from thermal cycling, Crystal Lake’s freeze-thaw pattern is particularly hard on refractory crowns. Water seeps in, expands overnight when temperatures drop below 20°F, and the crack propagates. By the time you can fit a nickel into it, water has likely reached the crown wash below.
- Spalling or flaking on the crown surface. The top layer of refractory concrete delaminates, often after a de-icing salt application drifts up from driveway runoff. What looks like cosmetic pitting is actually exposing the steel collar beneath to accelerated corrosion.
- Rust staining down the chimney face. DuraFlex crowns have a galvanized steel drip edge that channels water away from the masonry. When the crown cracks and water reaches this edge, rust bleeds down the brick in vertical streaks. In Crystal Lake’s older neighborhoods near Three Oaks Recreation Area, we see this on chimneys that haven’t been swept in three-plus years.
- Water pooling on the crown after rain instead of shedding. A properly pitched DuraFlex crown sheds water to all four edges. When the crown settles or the wash beneath compresses, a low spot forms. Standing water freezes, lifts the crown, and breaks the seal to the flue collar.
- Smoke odor or draft reversal on mild days. A compromised crown lets downdrafts enter the flue termination. The DuraFlex wind band can’t compensate if the crown itself is leaking air. You’ll notice it most in spring and fall when stack effect is weakest.
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AfterReplacement Cost & What’s Included
| Repair Type | Crystal Lake Price Range | What’s Included |
|---|---|---|
| Crown seal with flexible refractory compound | $340-$420 | Surface prep, crack chase, two-layer seal, photo documentation |
| Partial crown rebuild (under 40% surface area) | $450-$540 | Removal of damaged section, form and pour refractory patch, cure time, seal |
| Full DuraFlex crown replacement | $540-$620 | OEM or compatible crown, new gasket set, hardware, flue collar inspection, full photo record |
What drives the range: accessibility (steep roof pitch adds time), whether the flue collar beneath is salvageable, and if we find secondary water damage during the camera scan. Every repair includes a documented photo record under Haven Standard Clause 4, and the 365-Day Done Right Promise applies to all crown work. We deliver the written price before any tools come out, not after we’re on your roof.
DIY or Call Us?

There’s a safe middle ground here, and then there’s where DIY gets expensive.
What you can check from the ground: binoculars work fine for spotting rust streaks or missing crown chunks. A moisture meter on the ceiling near the chimney breast, read after heavy rain, will tell you if water is getting past the crown. Both are useful information to share when you call.
Where DIY goes wrong: DuraFlex crowns sit at height, on a sloped surface, and the refractory material is unforgiving. We’ve been called to Crystal Lake homes where a homeowner’s sealant job trapped water underneath, accelerating the damage. Worse, stepping onto a compromised crown to “get a closer look” has sent more than one person to the ER. The crown doesn’t warn you before it gives way.
We don’t recommend any owner work above the roofline. The camera doesn’t argue, and neither does a written price. Call (815) 923-3185 and we’ll scope it properly.
FAQs
A properly installed DuraFlex crown typically lasts 15-20 years in northern Illinois, though we’ve seen premature failure at 8 years when the original installer skipped the expansion joint or used non-refractory mortar. Crystal Lake’s freeze-thaw cycles, averaging 60+ days below freezing annually, stress the crown more than downstate installations. Call (815) 923-3185 for an exact assessment of your crown’s remaining life.
Yes, if the crack is under 1/8″ wide, doesn’t penetrate to the steel collar, and covers less than 40% of the crown surface. We chase the crack with a grinder, apply flexible refractory sealant in two layers, and document the repair with photos. If the crack is wider or the crown has settled out of pitch, replacement is the only lasting fix. We never recommend sealant as a band-aid for structural failure.
Crown sealing takes 2-3 hours including cure time between layers. A full replacement runs 4-5 hours because we remove the old crown, inspect the flue collar and wash beneath, dry-fit the new assembly, and seal with proper cure intervals. We book a half-day window and usually finish ahead of schedule. You’ll get a text when the technician is en route.
We carry both DuraFlexSS and DuraFlexHT crown assemblies, plus the full gasket and hardware sets, on every Level Two Chimney Crystal Lake truck. The most common sizes, 13″ × 13″ and 13″ × 17″, are always in stock. If your installation uses a discontinued size, our Haven buying network can source it within 48 hours, and we’ll schedule accordingly.
Written by Corrine Halstead, Owner, Level Two Chimney Crystal Lake at Level Two Chimney Crystal Lake, serving Crystal Lake and nearby areas.





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