White Stains On Chimney
Pat M writes: My new brick chimney has white streaks down the sides. Both the builder & the mason say the stains are normal & will go away on their own, but I am still concerned. Are they a long-term problem that I will have to worry about when my warranty runs out?
The white stains described are probably either efflorescence or calcium carbonate. Efflorescence occurs when water dissolves salts in brick & mortar, bringing them to the surface & leaving them on the face of the wall, these stains can usually be removed with water & a brush.
Calcium-carbonate stains are also caused by water in the brick which dissolves calcium hydroxide in the mortar & when exposed to carbon dioxide in the air forms calcium carbonate. These stains are thick, hard, crusty, & are not water soluble. Muriatic acid must be used to remove these stains.
Water in the wall is the cause of each case & an initial outbreak is fairly common & not a serious problem. If either persists over time, however, it is an indication that water is entering the brickwork on a regular basis & corrective measures would need to be taken in order to identify & repair the point of entry.
