Step 1: Identify the Leak Source

• Inspect your chimney inside and out for signs of water damage, such as discoloration, musty smells, or dripping water.
• Use a hose to test different sections of the chimney to pinpoint where water is entering.
• There are 2 main sources of leaks, we have saturation and water moving through the masonry, then improperly installed or deteriorated flashing.

Step 2: Repair or Replace the Chimney Cap

• Remove any broken or rusted chimney cap.
• Install a new cap with a proper fit and secure it tightly to prevent rainwater from entering.
• Your best option is going to be a full coverage cap that has a proper drip edge and meets all code regarding screen size. For more information, see Why Every Chimney Needs a Cap!

Step 3: Seal Cracks in the Chimney Crown

• Clean the crown surface and fill minor cracks with a waterproof masonry sealant.
• If the damage is severe, replace the crown entirely.

Step 4: Fix or Replace Flashing

• Check the flashing where the chimney meets the roof.
• Reseal gaps with roofing cement or replace flashing if it’s corroded or loose.

Step 5: Waterproof the Chimney

• Apply a high-quality, breathable masonry sealant to the chimney exterior.
• Avoid non-breathable coatings, as they can trap moisture and worsen damage. This includes paint that is not specifically made to allow masonry to breathe. You will end up trapping moisture on the inside, forcing it through to the inside of the chimney causing damage.

Step 6: Repair Damaged Mortar and Brick

• Remove crumbling mortar and replace it with fresh mortar (tuckpointing).
• Replace any severely damaged bricks to restore structural integrity.