Chimney Cap Damage

Chimney Cap - black arrow. This is a protective covering made out of mortar that protects the top of the chimney.

Brick and mortar chimneys are a common site on rooftops of a certain age in Washington State. A common point of deferred maintenance and long term damage is at the chimney cap. This is the mortar cap at the top of the chimney that protects the top of the chimney and bricks below. 

Mortar chimney cap cracked and flaking from long term water exposure. Water has been getting through those cracks for a long time. Water exposure, ice, snow and moss growth are all contributing to these cracks growing over time.

Water tends to pool and collect on the top of the chimney cap. This can lead to moss growth and erosion of the mortar which over the long term leads to cracks and cap failure. Eventually the cap will split and be in danger of falling off the chimney on to the roof or to the ground below. ​

If a chimney cap is at the point of damage like in these pictures, it needs to be repaired or replaced. Preventative maintenance is the regular cleaning of moss and the installation of a rain cap over the flue that extends over the edges of the chimney. 

Loose mortar chimney cap. Long term result of water exposure. This part of the cap is loose and wiggling up and down (arrows). There is a possibility of it falling to the roof or to the ground below.