Chimney Sweating In Attic

Leaks in the chimney structure.

Chimney sweating in attic. The wetness is more severe at the basement and or the first floor than the second floor or the roof. Since the entire height of the chimney in the kneewall area about 3 ft was wet we began to think of the chimney as a giant wick conducting moisture from its source wherever that was to most other regions of the chimney. Also there was a fair amount of wet sandy mortar on top of the attic insulation adjacent to the chimney indicating that the mortar was deteriorating. 2 many chimney leaks are from cracks in the chimney crown the chimney crown is the cement part on top of the chimney.

The pattern of wetness is relatively uniform on all the sides of the chimney exposed in the attic. Sweating as a result of condensation step 1 if the air inside the home is warm and humid and the walls of the chimney are cold this can result in sweating. The brick is colder than the air in the attic. Often ponding water will rust a hole in the simple flashing found on most chimneys.

Normal amounts of humidity and moisture in the hot air condense inside your chimney as the air cools leaving water which can be as acidic as bleach. Up the chimney the gas going up the chimney or exhaust pipe includes a large quantity of water vapor. When a fire is started the new warm air moving into the chimney comes into contact with the cold chimney walls causing condensation. Over time this acidic moisture can do serious damage to your chimney and masonry work but that s not the worst of it.

When the warm air of the house comes into contact with the cold wall that separates the living space from the chimney water from the air will condense onto the wall s surface. Code requires a chimney have a cricket if it is thirty inches or wider. The bricks go up around the tile flue liners but at the top you need something to stop the rain and snow from just falling in around the tiles. The sweating in this case is normal and will cease once a fire is built and the chimney heats up.

That s why condensation is forming on the brick. A condensation effect also can happen within the chimney itself. White and tan mineral deposits on the surface of the chimney plaster or drywall. When everything is working properly the vapor is pushed up out of the the end of the pipe and.

If you see water entry in the attic on the uphill side of the chimney we know a chimney cricket is needed so water is not ponding in this area. If left untreated it can damage critical structural elements of the home such as the trusses and rafters ruin insulation damage any stored belongings and lead to the formation of potentially toxic black mold. Condensation in the attic is a serious problem that must be addressed by homeowners.