Why Chimney Flashing Repair in Flower Mound Is the First Leak to Check
Flashing is the metal that seals the gap between the chimney and the roof deck. Rain hits the chimney, runs down the brick or siding, and has to be carried out over the shingles instead of into the attic. When the flashing lifts, rusts or loses its sealant, water goes straight down the outside of the chimney into the house. Flower Mound Chimney Sweep Professionals repairs chimney flashing on masonry and prefab chimneys across Flower Mound, Lewisville and Southlake.
Flashing has three parts, and a leak can come from any of them:
- Step flashing: L-shaped pieces woven between shingle courses along the sides of the chimney.
- Counter flashing: metal set into a cut mortar joint (a reglet) on the chimney and lapped down over the step flashing.
- Apron and back pan: the front piece under the shingles and the rear piece that carries water around the uphill side. Chimneys more than 30 inches wide need a cricket here under the residential building code.
On a prefab chimney wrapped in siding, the counter flashing tucks behind the siding instead of into mortar, and the chase cover above it matters just as much. We check both.
Signs Your Chimney Flashing Needs Repair
- Water stains on the ceiling or drywall at the base of the chimney
- A leak that appears during wind-driven rain and not in light rain
- Lifted or bent metal where the chimney meets the roof
- Cracked, dried or missing sealant along the top edge of the counter flashing
- Rust streaks on the roof below the chimney
- Daylight visible from the attic beside the chimney
- Shingles replaced recently with the old flashing left in place
- Hail dents in the flashing after a spring storm
The National Weather Service office in Fort Worth tracks the hail and wind events that hit Denton County every spring. After one of them, a roof check of the flashing, crown and cap is worth booking even if nothing is leaking yet.
How We Repair Chimney Flashing
- Inspect and test. From the roof we photograph every side of the flashing and check the mortar joints it sits in. If the leak is not obvious, we run water on one section at a time while someone watches inside.
- Quote. Photos and a written price on the same visit. The estimate is free.
- Repair. The fix matches the damage:
| Problem found | Repair |
|---|---|
| Sealant dried or cracked, metal sound | Clean the joint, reseal with a polyurethane or butyl flashing sealant |
| Counter flashing pulled out of the mortar joint | Grind the reglet, re-bed the metal in mortar or sealant, re-seal the top edge |
| Rusted, bent or missing step flashing | Lift shingles, install new step flashing and counter flashing, replace shingles |
| Wide chimney with water pooling behind it | Build and flash a cricket on the uphill side |
| Prefab chimney with flashing tucked behind rotted siding | Repair the siding and chase, then re-flash |
- Finish. We photograph the completed flashing and water-test it again before we leave.
Resealing and re-bedding take a half day. A full replacement with a cricket is usually one day.
Why Flashing Fails in Flower Mound
Three things work against flashing here. Summer heat above 100 degrees dries out sealant in a few seasons. Spring hail dents and lifts the metal and cracks the mortar joints the counter flashing sits in. And the roofing boom after each hail storm means a lot of chimneys get new shingles with the old flashing bent back into place instead of replaced. If your leak started after a roof replacement, that is the first place we look.
Chimney Leak Repair
Flashing is the most common cause of a leak at the base of a chimney, but water in the firebox or on the damper usually comes from the top, from the crown or cap. On a chimney leak repair call we check all five entry points before we quote, so you pay for the right fix.
Chimney Crown Repair
Water running down the outside of a masonry chimney often starts at a cracked crown, then finds the flashing on the way down. If the crown is cracked, we quote chimney crown repair on the same visit, since sealing the flashing under a leaking crown only moves the problem.
Chimney Chase Cover Replacement
On a prefab chimney, the flashing and the chase cover share the job of keeping water out of the wood chase. A rusted galvanized cover leaks into the chase and shows up as a stain that looks like a flashing leak. We check the cover on every flashing call and quote a stainless chimney chase cover replacement when it is the real cause.
Chimney Waterproofing
Once the flashing is sealed, a breathable water repellent on the brick above it keeps the masonry from soaking up rain and wicking it down to the roofline. Chimney waterproofing is a finishing step after the repair, not a substitute for one. For other repairs, see the main chimney repair page.
Book Chimney Flashing Repair in Flower Mound
Flower Mound Chimney Sweep Professionals is veteran-owned and based on Long Prairie Rd in Flower Mound 75028. We repair chimney flashing in Flower Mound, Lewisville, Southlake, Colleyville, Keller, Fort Worth and Collin County, 7 days a week from 7 AM to 8 PM. Call (817) 518-6131 or send the form on this page. You get roof photos, a free written estimate and a firm price before we start. Not sure where the water is coming from? Book a chimney inspection and we will find it.
