When water starts dripping near your fireplace or staining your ceiling, one of the most common — and frustrating — culprits is failed chimney flashing. For homeowners across Union, Washington, Festus, and the surrounding areas, chimney flashing issues are more than just inconvenient. They’re a real threat to your home’s structure and interior.
At Emmendorfer Exteriors, we’ve helped hundreds of homeowners tackle this problem. In this guide, we’ll walk you through everything you need to know about chimney flashing repair, including how to identify flashing leaks, fix existing problems, and prevent them from happening again.
What Is Chimney Flashing and Why Does It Matter?
Chimney flashing is the metal or waterproof membrane that seals the junction where your chimney meets your roof. Because this intersection is one of the most vulnerable spots on your roofing system, flashing plays a vital role in directing water away from the seams.
Proper flashing includes several layers:
- Step flashing embedded under shingles
- Counter-flashing built into the chimney masonry
- Base flashing underneath both
When flashing is properly installed, it provides long-lasting protection. But when it fails — either from poor installation, age, or storm damage — water starts to find its way into your attic or home interior.
That’s when chimney flashing repair becomes urgent.
Common Signs of Chimney Flashing Leaks
If you live in St. Clair, Pevely, Eureka, or anywhere in between, here’s how to spot a chimney flashing issue before it becomes a major problem:
- Water stains on walls or ceilings near your chimney
- Damp, musty smells near the fireplace
- Dripping noises during or after rainstorms
- Visible rust or corrosion on flashing material
- Cracks in the caulking or separation from masonry
- Loose or missing shingles near the chimney
These signs might not always be obvious, which is why annual roof inspections are recommended — especially in weather-prone regions like Union and Festus.
Why Chimney Flashing Fails
There are several reasons chimney flashing fails, all of which lead to the need for chimney flashing repair. Common causes include:
- Aging Materials: Flashing can corrode, rust, or break down over time.
- Improper Installation: If step or counter flashing wasn’t properly layered, leaks are almost guaranteed.
- Separation from Masonry: Masonry expands and contracts, causing flashing to pull away.
- Severe Weather: Hail, snow, and high winds (especially in towns like Valley Park or Herculaneum) can dislodge flashing.
- Roof Settling: Over time, the roof can shift slightly, compromising the flashing seals.
Understanding the root cause helps determine whether you need a simple reseal or a full flashing replacement.
Step-by-Step Chimney Flashing Repair Guide
Step 1: Inspect the Flashing
Start with a visual inspection. Use binoculars from the ground, or carefully climb a ladder (if you’re experienced and have proper safety gear). Look for:
- Rust
- Bent or warped flashing
- Gaps between the flashing and chimney
- Deteriorating sealant or mortar
If you spot one or more of these, you likely need chimney flashing repair.
Step 2: Remove Old Caulking or Sealant
Use a utility knife or scraper to remove old caulk where the flashing meets the chimney. If any part of the flashing is loose, carefully lift it to inspect underneath. Be cautious not to damage nearby shingles.
Step 3: Replace Damaged Flashing (if necessary)
If the flashing is rusted, cracked, or missing altogether, full replacement is your best option. This involves removing shingles and old flashing, cutting new flashing pieces, and layering them properly.
In Union, Gerald, and other historic Missouri towns, older homes often have nonstandard flashing or layered roofing that requires custom flashing fabrication.
Step 4: Apply High-Quality Sealant
For minor repairs or to reseal existing flashing, use a roofing-specific polyurethane sealant (not just generic caulk). Apply a clean bead where the flashing meets the chimney bricks and the shingles.
Let it dry fully — usually 24 to 48 hours — before expecting waterproof performance.
Step 5: Reinstall Shingles and Inspect
Re-secure any shingles you lifted and ensure everything lays flat. If needed, nail and seal replacement shingles to cover exposed flashing. Test your repair by gently spraying the area with water and checking for leaks inside the home.
When to Call the Pros for Chimney Flashing Repair
While some minor flashing fixes are DIY-friendly, many repairs are best handled by professionals — especially when:
- There’s water damage inside your home
- The chimney structure itself is cracked or shifting
- You’re unsure whether the leak is from flashing or the chimney crown
- The flashing requires cutting into masonry
- You want a long-term warranty-backed solution
In areas like Fenton, DeSoto, or Festus, many homes have steep roofs or tall chimneys that require specialized equipment and safety gear. Hiring licensed professionals like Emmendorfer Exteriors ensures the job is done correctly and safely.
Chimney Flashing Repair Costs in Missouri
On average, chimney flashing repair in Missouri ranges from $350 to $1,000, depending on the extent of damage and roof accessibility. Full flashing replacements — which may involve partial roof and chimney work — can run $1,000 to $2,500 or more.
Factors affecting cost include:
- Roof height and pitch
- Number of chimneys
- Type of flashing material used (aluminum, copper, galvanized steel)
- Whether shingles also need to be replaced
- Permit requirements in towns like Eureka or Washington
Always get a detailed quote and ask about warranties before starting.
Preventing Future Chimney Flashing Leaks
The best way to avoid costly chimney flashing repair is to prevent leaks before they start. Here’s how:
- Schedule annual roof inspections, especially after winter storms or high winds
- Check your attic for moisture near the chimney base during rain
- Keep your gutters clean to prevent backup around flashing
- Seal brick joints with proper mortar to stop moisture wicking
- Install a proper cricket behind the chimney if it’s wide (required in many codebooks)
Preventative maintenance not only protects your chimney — it helps preserve your entire roofing system.
Material Options for Chimney Flashing
If you’re investing in full chimney flashing repair, consider upgrading your materials. Common flashing materials include:
- Aluminum: Affordable and rust-resistant, but not as long-lasting
- Galvanized steel: Sturdy and commonly used, but may corrode over time
- Copper: Premium, extremely durable, and visually appealing — ideal for historic homes in places like Gerald and Washington
- Lead (rare today): Found on very old homes; usually replaced due to safety concerns
Your contractor can recommend the best material for your home’s design and climate.
Why Homeowners in Union, MO and Surrounding Areas Trust Emmendorfer Exteriors
We’ve repaired hundreds of roofs and chimneys throughout Union, St. Clair, Valley Park, and beyond. Our crew understands the unique architecture and seasonal wear in Missouri’s homes — from older brick chimneys to modern wood-framed designs.
When you hire us for chimney flashing repair, we provide:
- A full roof and chimney inspection
- Detailed photo reports before and after
- Permit handling if required
- Manufacturer-grade materials
- Workmanship warranties for peace of mind
Whether you need a quick patch or full flashing replacement, our team ensures your roof and chimney stay watertight year-round.
Final Thoughts: Protecting Your Home with Proper Chimney Flashing Repair
Chimney leaks may start small, but they never stay that way. What begins as a minor drip can lead to attic mold, ceiling stains, or even structural wood rot — especially in weather-prone areas like Pevely or Eureka.
By addressing problems early and working with experienced professionals, you can take control of your roofing system and avoid costly water damage. Whether you live in Union, DeSoto, Festus, or anywhere nearby, Emmendorfer Exteriors is here to help with expert-level chimney flashing repair that lasts.
If you’ve noticed stains near your chimney, heard water dripping during rain, or haven’t had your flashing inspected in years — now is the time to act. Schedule an inspection with our team today and keep your home safe, dry, and protected through every season.
