What is "Efflorescence"?
Posted by Richard Brienza on Mon, Feb 28, 2011 @ 08:56 AM
Efflorescence is a white, chalky substance that appears on masonry walls. Efflorescence generally is found on new construction, but can be any place that water can collect and migrate. In order for efflorescence to occur you must have water, soluble salts, a pathway for migration of the salts, and a force, such as hydrostatic pressure or evaporation, to move the water that is carrying the salt. Let’s take a look at where the salt comes from first. There are salts in just about everything used to construct concrete masonry, or brick walls. Block, brick, grout, and mortar of all types contain salt. The water used in construction contains salt. The sand used also contains salt. When cement hydrates, the calcium hydroxide produced is also a form of salt. Salt must come in contact with water and form a solution in order to move through a wall. Water is the easiest cause of efflorescence that we can control. Water that is used in the initial construction process is necessary to complete the job. Additional water that is introduced to a wall can be deemed as the “culprit” for efflorescence. This water needs to be controlled or managed. Management of this water needs to be done through various vehicles. The first place where efflorescence can be managed is by the designer. Proper wall design is critical. There is no such thing as a waterproof masonry wall. Therefore “water management” is essential. Flashing, weep holes, and vents must be engineered properly. The designer must think in terms of using all available methods of water management as a system. Waterproofing agents can bridge the materials matrix and also prevent efflorescence. Efflorescence is generally an aesthetic problem and easily cured once you understand what causes it. Think water when troubleshooting efflorescence. Eliminate the water and you will eliminate efflorescence.