What causes water leaking from a chimney?
Short answer. Water leaking from a chimney comes from one of a handful of places: the flashing where the chimney meets the roof, the crown on top, a missing cap that lets rain down the flue, porous brick and eroded mortar, or, on framed chimneys, a rusted or flat chase cover. Condensation inside the flue can also produce water that looks like a leak.
The common causes
- Flashing: step flashing, counterflashing and the front apron. This is the most common cause, especially where counterflashing was caulked to the brick face instead of set into the mortar.
- Missing cricket: a chimney wider than 30 inches without a cricket behind it collects water on its uphill side.
- Cracked crown: the sloped concrete top around the flue tiles. Cracks let water into the chimney's core.
- No chimney cap: rain falls straight down the flue onto the damper and into the firebox.
- Porous masonry: old brick and eroded mortar joints absorb wind-driven rain and release it indoors.
- Condensation: exhaust from gas appliances or a cold, unused flue can condense into water inside the chimney.
Framed chimneys are common in Georgia
Many Georgia homes from the 1980s onward have a factory-built fireplace inside a framed chimney chase sided to match the house. These leak in their own ways: a flat or rusted metal chase cover on top that pools water and rusts through, siding without proper step flashing where the chase meets the roof, and a missing kickout at its base. A sloped stainless or galvanized replacement cover usually solves the top.
Narrowing it down
- Water in the firebox or at the damper: the top of the chimney, meaning the cap, crown or chase cover.
- Stains on the ceiling or wall beside the chimney: the flashing or a missing cricket.
- Damp brick indoors or white deposits on the brick: water absorbed through the masonry.
Roofers handle flashing, crickets and the joint where a chase meets the roof; masons and chimney professionals handle crowns, caps, liners and repointing. See chimney leaks and crickets and roof flashing explained.