When winter hits NYC and Long Island, your chimney faces more stress than any other time of year. Snow settles on the crown, ice forms along the bricks, and freezing temperatures push moisture deep into tiny cracks you may not even know exist. Then, as everything thaws, that trapped water expands and forces its way into your home. Many homeowners don’t realize their chimney leaks start long before spring rain—most of the damage actually happens during winter storms and freeze-thaw cycles. If you’ve ever noticed water stains near your fireplace after a snowstorm, you’re seeing the early signs of a winter-related chimney leak.
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If you’ve ever walked outside after a snowstorm and noticed water stains near your fireplace, you’re not alone. A homeowner in Huntington once told me she thought her “roof was leaking”… but a quick look at her chimney told a different story. Melted snow from the previous night had seeped into tiny cracks in her masonry, refroze, and widened those gaps like nature’s crowbar. By morning, she had a full-on chimney leak.
It’s a reminder that snow and ice don’t just sit harmlessly on your roof—they can damage your chimney in ways most people never see coming.
Let’s break down how winter weather affects your chimney and what homeowners in NYC and Long Island can do to prevent leaks before spring arrives.
How Snow and Ice Actually Cause Chimney Leaks
Most chimney leaks start long before you ever notice a drop of water inside your home. Winter weather simply exposes the weaknesses.
Freeze-Thaw Cycles Are the Main Culprit
During the winter, water from melting snow seeps into microscopic cracks in your bricks, mortar joints, or chimney crown. When temperatures drop again, that water freezes and expands—pushing those cracks wider each time.
This cycle leads to:
- Cracked bricks
- Loose mortar
- Deteriorating crowns
- Gaps around the chimney flashing
Once that happens, water easily finds its way inside.
Ice Dams Make the Problem Worse
Ice dams form when heat escaping through your roof melts snow, which then refreezes at the edges. When the ice dam traps water near your chimney, it can force that water into weak spots around the flashing or masonry.
In older NYC homes—especially in Queens, Brooklyn, and the Bronx—chimneys often sit near valleys in the roof, making ice dams even more common.
Common Signs of Chimney Leaks During Winter
Most homeowners don’t realize the issue begins from the outside. By the time you see indoor symptoms, the damage has already started.
Here’s what to look for:
Water Stains or Damp Walls Near the Fireplace
If snowmelt is seeping through your chimney structure, you might notice dark patches, bubbling paint, or crumbling plaster.
Rust on the Damper or Firebox
Melting snow that travels down the flue can cause rust to form quickly.
Efflorescence on Exterior Brick
This white, powdery residue is a classic sign of water movement through masonry.
Dripping Sounds When Snow Melts
Some Long Island homeowners describe it as “hearing the leak before seeing it.”
If you notice any of these, you’re likely dealing with winter-related water intrusion.
What Parts of the Chimney Snow and Ice Damage Most
Your chimney is made up of several components—and winter weather targets each of them differently.
The Chimney Crown
This is your chimney’s “roof.” When it cracks, water pours straight down into the structure. Ice widens those cracks dramatically.
The Masonry (Bricks & Mortar Joints)
Brick is durable but porous. Snowmelt that freezes inside it can cause spalling—when the brick face breaks off—which is common in coastal areas like Long Beach, Freeport, and Island Park.
The Chimney Cap
If your cap is missing or damaged, snow falls directly into the flue. When it melts, it often travels into walls or ceilings instead of evaporating safely.
Chimney Flashing
This metal barrier seals the gap between your roof and chimney. Ice dams often force water right underneath it.
How to Prevent Chimney Leaks in Snowy or Icy Weather
The good news? Most winter chimney leaks are preventable with a little proactive care.
Schedule an Annual Chimney Inspection
A Certified Chimney Service technician can spot vulnerabilities long before snow and ice take advantage of them. This is especially important before the first freeze of the season.
Repair Cracks and Deteriorated Mortar
Tuckpointing (replacing old mortar) restores the chimney’s strength and prevents water entry.
Install or Replace Your Chimney Cap
A good stainless-steel cap keeps snow, ice, and animals out while protecting the flue.
Add a Waterproofing Sealant
A vapor-permeable sealant keeps water out while letting the chimney breathe—critical for preventing trapped moisture.
Inspect the Roof Flashing
This ensures no gaps are forming around the base of your chimney where snow and ice tend to pool.
Protect Your Home Before the Next Storm Hits
Snow and ice may look harmless, but winter weather is one of the biggest causes of chimney leaks across NYC and Long Island. If you’ve seen staining, heard dripping, or suspect freeze-thaw damage, our certified technicians can help.
Call Certified Chimney Service at 877-793-3712 to schedule an inspection or winter chimney repair.
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