Leaky Chimney? What’s Really Going On—and How to Stop It

A leaky chimney is more than just an inconvenience—it’s a serious issue that can lead to costly structural damage if left unchecked. At Bollerud & Sons Masonry, we’ve seen firsthand how Wisconsin’s unpredictable weather puts extra strain on brickwork, mortar, and chimney systems. Understanding why leaks happen and how to fix them will not only protect your chimney but also safeguard your entire home.



Common Causes of Chimney Leaks

Chimneys are constantly exposed to rain, snow, and freeze-thaw cycles, making them highly vulnerable to water intrusion. Some of the most frequent culprits include:

• Cracked or Missing Mortar Joints
  Mortar is the glue holding your bricks together, but over time it deteriorates. Gaps let water seep inside, leading to both leaks and structural weakness.
• Damaged or Missing Chimney Cap
  A chimney cap is your first line of defense against rain and snow. Without it, water flows directly into your flue.
• Compromised Flashing
  Flashing seals the gap where your chimney meets the roof. If it becomes corroded or pulled loose, leaks are almost inevitable.
• Absorbent Brickwork
  Bricks are porous. Without proper sealing, they absorb water like a sponge. When freezing temps hit, trapped water expands, causing cracks and spalling.

Why Moisture Is a Masonry Enemy

Moisture is especially destructive for masonry. Once inside, water weakens mortar, corrodes metal liners, and even damages interior drywall and ceilings. Long-term exposure can compromise your chimney’s structural integrity, leaving you with repairs far more costly than preventive maintenance.

Proven Solutions for a Dry Chimney

At Bollerud & Sons Masonry, we use professional methods to keep chimneys watertight, including:

• Tuckpointing — Replacing deteriorated mortar with fresh, durable joints.
• Installing or Repairing Chimney Caps — Preventing direct water intrusion.
• Flashing Repair or Replacement — Creating a watertight seal at the roofline.
• Professional Waterproofing Treatments — Applying breathable sealants that protect brick while allowing moisture vapor to escape.

When to Call the Experts

If you notice water stains near your fireplace, musty odors, or visible brick deterioration, don’t wait. Chimney leaks never get better on their own—they only get worse. Acting quickly can save you thousands in repairs and extend the life of your home’s masonry.

Protect Your Home with Bollerud & Sons Masonry

For over 40 years, Bollerud & Sons Masonry has helped Milton and southern Wisconsin homeowners keep their chimneys and foundations strong. From tuckpointing to full waterproofing, we’re here to ensure your chimney performs safely and reliably.

Call us today for a free inspection and keep your home protected against leaks this season.