My Chimney Is Leaking Through

Symptoms

• Homeowners who have water leaks around their chimney may experience water damage inside their home. Water spots may be visible on the ceiling over the fireplace and water may trickle inside the fireplace. Walls near your leaking chimney may become stained or discolored. Excess indoor moisture often causes homes to feel damp or have a musty smell.

Causes

• According to North Dakota State University Extension, one common cause of chimney leaks is defective building materials. Flashing is sheet metal, typically used to waterproof homes where the chimney meets the roof. Improperly fitted flashing allows moisture to seep through and leak into the home. Another common cause of chimney leaks is loose or crumbling mortar in the brickwork of the chimney itself. As time goes on, mortar joints can develop gaps, crumble and allow bricks to become loose, causing water leaks into the chimney.

Diagnosis

• Examine your roof to determine the cause of your water leak. When the roof has wet spots near the chimney or the outside wall near the chimney is wet, the problem is most likely overly narrow or defective flashing. Check around the base of the chimney for signs of crumbling furnace cement. If large sections are missing or brittle, aging mortar is the most likely cause. Any missing shingles around your chimney may also allow moisture inside your home. Inspect your home's shingles thoroughly to determine if any are damaged or missing.

Solution

• Damaged or missing shingles are fairly simple for most homeowners with home repair experience to replace. If mortar is crumbling or missing, chisel it out to a depth of 1 inch and refill the joints with chimney mortar, which is meant to stand up to fluctuating temperatures. Defective flashing or narrow flashing is more difficult to repair and should be done by a roofing contractor. Once your leak is repaired, examine any areas of water damage for signs of mold growth. Scrub mold away with a stiff bristled brush and liquid dish detergent. Rinse and pat dry when mold is gone. Repair any future water leaks as soon as possible to avoid mold growth inside your home. Mold can damage the structure of your home if allowed to remain on surfaces such as wood or drywall.