What Chimney Waterproofing in Flower Mound Does
Brick and mortar are porous. A masonry chimney above the roofline stands in every rain with nothing over it but the crown, and the brick soaks up water like a sponge. Chimney waterproofing from Flower Mound Chimney Sweep Professionals is a water repellent that soaks into the brick and mortar and lines the pores so water beads off instead of in, while water vapor from inside can still get out. We use it as the last step of a chimney repair on masonry chimneys in Flower Mound, Lewisville and Southlake.
That last-step rule matters. Water repellent on a chimney with a cracked crown or lifted flashing does nothing for the leak, and water repellent on wet brick seals the water in. So every waterproofing job starts with the same inspection as a leak call: camera in the flue, roof check of the crown, cap, flashing and mortar joints, photos and a written price for anything that needs fixing first.
Breathable Repellent vs. Sealer: The Difference That Matters
| Breathable water repellent (what we use) | Film-forming sealer (what to avoid) | |
|---|---|---|
| Chemistry | Siloxane or silane, soaks into the pores | Acrylic, silicone or paint, forms a skin on the surface |
| Water vapor from inside | Escapes through the brick | Trapped behind the film |
| Result in heat and freeze | Brick stays dry and sound | Trapped water expands, brick faces spall off |
| Appearance | Clear, no gloss, brick looks the same | Sheen, often darkens the brick |
| Reapply | Every 5 to 10 years | Peels, hard to remove once it fails |
The National Park Service’s Preservation Brief on water-repellent treatments for masonry explains why coatings that block vapor damage brick and why repair of the actual leak comes before any treatment. The same rules apply to a 1990s chimney in Bridlewood as to a historic building.
Signs Your Chimney Needs Waterproofing
- The whole face of the chimney stays dark and damp for a day after rain
- White, chalky deposits (efflorescence) on the brick above the roof
- Brick faces flaking or popping off (spalling), especially near the top
- Mortar joints that are sandy or recessed from the brick face
- A musty smell from the fireplace after storms with no obvious leak
- Moss or green staining on the shaded north side of the chimney
- The chimney was built in the 1980s or 1990s and has never been treated
Spalling and efflorescence mean water has been moving through the brick for a while. Those chimneys usually need chimney tuckpointing or brick replacement before the repellent goes on.
How We Waterproof a Chimney
- Inspect and repair first. Crown, cap, flashing and mortar get fixed. Efflorescence gets cleaned off. Photos at each step.
- Dry time. The masonry needs several dry days after repairs or heavy rain. Repellent on damp brick does not soak in.
- Mask. Roofing, the cap and any metal get covered so the product lands on brick and mortar only.
- Apply. Two coats, sprayed wet-on-wet from the bottom up, on every exposed face from the roofline to the crown, including the underside of the crown overhang.
- Cure. No rain for 24 hours. We schedule around the forecast, which in Flower Mound usually means avoiding spring storm fronts.
- Report. After photos and the application date, so you know when the next treatment is due.
The application itself takes about an hour. The repairs before it set the total time on site.
Why Flower Mound Chimneys Need It
North Texas weather is hard on bare brick. Summer heat above 100 degrees bakes the top of the chimney and opens hairline cracks in the mortar. Spring storms drive rain sideways into those cracks. Winter brings a few hard freezes a year, and water inside the brick expands when it freezes and pops the face off. Humidity the rest of the year keeps the masonry from drying out. Masonry chimneys in the older neighborhoods near Grapevine Lake and Lake Lewisville are now 30 to 40 years old, and the mortar is at the age where water gets through.
Chimney Crown Repair
The crown is the single biggest source of water in a masonry chimney, and no repellent on the brick fixes a cracked crown. We seal, patch or replace it before waterproofing. See chimney crown repair.
Chimney Tuckpointing
Repellent cannot bridge a mortar joint that has worn back a quarter inch. Worn joints get ground out and refilled, the mortar cures, and then the repellent goes on over brick and new mortar together. The chimney tuckpointing page covers how we match the mortar.
Chimney Leak Repair and Flashing
If you have an active leak, start with chimney leak repair so we find the source, or chimney flashing repair if the stain is at the base of the chimney. Waterproofing is the finish on those jobs, and a line item on the same written estimate when the brick needs it. A yearly chimney maintenance visit keeps track of when the treatment is due. For everything else, see the main chimney repair page.
Book Chimney Waterproofing in Flower Mound
Flower Mound Chimney Sweep Professionals is veteran-owned and based on Long Prairie Rd in Flower Mound 75028. We waterproof masonry chimneys 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.
