How Improper Chimney Flashing Installation Can Cost You Thousands in Repairs

thechimneyguysclea
Sep 14
3 min read

Updated: Sep 16

If you own a home in Philadelphia or the surrounding counties, your roof takes a beating from heavy rain, snow, and freeze-thaw cycles. One area that often gets overlooked? The chimney flashing.

Flashing is a thin strip of metal that seals the joint where your chimney meets your roof. When installed properly, it keeps water out and protects your home. But when flashing is installed incorrectly, leaks develop — and the hidden water damage that follows can cost homeowners thousands in repairs.

In this post, Chimney Masters Cleaning and Repair LLC explains why improper chimney flashing installation is such a problem, what signs to look for, and the best solutions to protect your home.

What Is Chimney Flashing and Why Proper Installation Matters

Chimney flashing is more than just sheet metal around your chimney. It’s a layered, protective system designed to channel water away:

Base flashing directs water down the roofline.
Step flashing integrates with shingles to form a continuous barrier.
Counter flashing embeds into mortar joints, sealing the system from above.

When installed incorrectly — such as using roof tar instead of counter flashing, or failing to embed metal properly — gaps form. Water seeps in unnoticed, damaging roof decking, insulation, drywall, and even structural beams.

Common Problems With Improper Chimney Flashing Installation

1. Tar-Sealed Flashing

Some contractors use roofing tar instead of true counter flashing. Tar breaks down quickly, leaving cracks for water to enter.

2. Missing Step Flashing

Without step flashing woven into shingles, water flows directly into the roof instead of being directed away.

3. Shallow or Loose Counter Flashing

If metal isn’t embedded into mortar joints, it pulls away easily during storms or roof shifting.

4. Wrong Materials Used

Cheap galvanized steel rusts fast in Philadelphia’s damp climate, creating pinholes and leaks.

5. Poor Integration With Roofing

If the flashing wasn’t replaced during a roof replacement, the old system often fails prematurely.

Warning Signs of a Flashing Leak

Improper installation usually doesn’t show right away. But as water intrusion builds, you may notice:

Brown water stains on ceilings or walls near the chimney
Musty odors in your attic or fireplace
Rust, loose edges, or peeling flashing around the chimney base
Warped shingles or moss growth near the flashing
Water dripping into your firebox after rain

Solutions That Actually Work

At Chimney Masters Cleaning and Repair LLC, we never rely on short-term patches like caulking or cement. Our certified technicians use proven methods:

Professional Flashing Replacement – Installing step and counter flashing made of durable aluminum or copper, embedded into mortar.
Masonry Repair and Repointing – Restoring mortar joints to anchor flashing securely.
Waterproofing Treatments – Applying breathable sealants to protect masonry without trapping moisture.
Chimney Crickets (if needed) – Adding a peaked structure behind wide chimneys to divert water.
Annual Inspections – A simple check each year prevents small gaps from becoming major leaks.

Why Philadelphia Homes Are at Higher Risk

Freeze-thaw cycles: Water in cracks freezes, expands, and makes gaps worse.
Historic homes: Many older properties still have outdated flashing systems.
Extended wet seasons: Heavy rains and snow speed up rust and deterioration.
Tree debris and moss: Organic matter traps moisture against your chimney base.

How We Repair Improperly Installed Flashing (Step-by-Step)

Full inspection using moisture meters and visual checks.
Removing old or improperly installed flashing and sealants.
Repairing masonry if mortar joints are cracked or missing.
Installing new step and counter flashing correctly, embedded into mortar.
Applying waterproof sealants designed for Philadelphia’s weather.
Final inspection and cleanup for a guaranteed leak-free finish.

Cost of Chimney Flashing Repair in Philadelphia

Minor resealing or touch-ups: Affordable but temporary
Partial flashing replacement: Moderate cost, ideal if some sections are salvageable
Full flashing replacement: Higher cost but the longest-lasting solution

Price factors include:

Material choice (copper lasts decades, aluminum is more budget-friendly)
Roof height and accessibility
Masonry condition
Extent of existing water damage

Don’t Wait Until It’s Too Late

Even a small flashing leak can spiral into rotted roof decking, ruined drywall, and dangerous mold. The good news? Acting early prevents thousands in damage.

At Chimney Masters Cleaning and Repair LLC, we: