Understanding the potential problems your chimney could suffer from, might help you prevent these problems before they cause any serious problems. You can use this page to identify the different parts of your chimney and learn what problems they might face.
Open chimney pots on top of unused chimney flues can allow rain water to enter internally. When chimneys are in use this isn't a problem as warm air from the fire rises up the chimney and dries the flue. If the fire is no longer in use the moist chimney flue won't dry out effectively and during periods of prolonged rainfall the moisture inside the chimney flue can seep through the brickwork causing damp inside the property.
Also known as the crown or chimney benching, a strong concrete flaunch on top of the chimney is probably the most important part of good chimney maintenance. It is the flaunching on top of a chimney that directs water off the top preventing it from getting inside the flue or masonry. When moisture is allowed to get into the chimney's brickwork the erosion it causes happens at an ever increasing rate. This can cause penetrating damp inside the property and serious structural problems or collapse.
Weak and missing mortar joints often cause penetrating damp on a chimney breast inside the home. The mortar joints form a water tight seal between the bricks of the chimney. When the mortar joints become weak they become porous allowing moisture to soak into the brickwork, this can be very damaging to the bricks themselves often causing them to loose their water resistant face. When mortar joints start to become weak and vulnerable, the eroding damage that moisture causes can speed up at a ever increasing rate as more and more vulnerable patches appear.
The lead flashing around the bottom of the chimney seals the joint between the chimney's brickwork and the roof. A common problem with the flashing is the mortar joint where the lead laps into the brickwork cracks and falls out due to the expansion and contraction of the lead at different temperatures. Water then finds its way behind the lead work as it runs down the face of the bricks. This problem can also cause the lead to fall off the chimney leaving the joint between the chimney and the roof vulnerable.
Often under lead work, tin soakers are used along the side of the chimney below the step flashing, these tin soakers can corrode leaving holes in the flashing.
Soakers can be found underneath the tiles or slates, next to stepped flashing. The soakers lap over the tiles and under the stepped flashing to prevent water running off the flashing and getting underneath the tiles. On older properties the soakers are often made from tin, over many years the tin can rust leaving holes that allow water to penetrate inside the building.