What Is Efflorescence and How to Prevent It

Many New Jersey homeowners are familiar with efflorescence as a white, powdery substance that finds the ideal “growing conditions” in crawl space. Efflorescence, however, can appear on any concrete, stone, brick, or stucco surface. It is particularly likely to form immediately following a cold, wet winter. New Jersey’s warm, humid summers naturally fight this problem, but the other seasons are not so immune.

What Is Efflorescence?

Look at this wall. Efflorescence from the ceiling to the floor. Don’t see this that often. Most contractors will tell you that you need a french drain and a sump sump pump. But if you understand the science, you would know that a french drain will not help. This is being caused by a faulty sprinkler head saturating the exterior of the home.

Efflorescence sometimes referred to as “whiskers,” consists of salt deposits left by evaporated water. Salt crystals, dissolved in water, are carried into or onto the affected building material. Once the water has evaporated, the water-soluble salts are left behind. The water must have a channel by which to contact the building or else seep to it through a porous substrate. Capillary action accounts for the movement of salt-bearing water to and through the materials it affects. In essence, water wicks upward from the soil into the structure.

The quantity and appearance of these deposits vary greatly based on the type of salt involved. Vanadium, for example, results in a greenish deposit. Chlorides, nitrates, and most other problematic salts yield a whitish or grayish effect. Also, note that more highly soluble salts will make larger deposits.

How Can I Prevent Efflorescence?

By eliminating the sources of the problem as much as possible, you can minimize the chances of your building is affected. First, using concrete with a low absorption rate is the best way to defend your foundation. A high cement-to-water ratio, tight compaction, proper curing will lower concrete’s absorption rate. If your foundation is already poured and has a relatively high absorption rate, you will likely see efflorescence in early spring for about three years. It should decrease in intensity as time goes by, however.

Watch out for sand, rock, or gravel landscaping materials next to your foundation. Most provide marketing services wash the salts off of these materials at the plant, but you could not go wrong double-checking or giving them an extra wash.

Clay or brick products also can contain salts, but most of the highly soluble ones are washed off during manufacturing. You can test bricks by standing them on end in a basin of distilled water. Water will wick up to the opposite end of the brick and evaporate, leaving you a clue as to how much efflorescence that brick will produce. It is also important to store bricks in a dry place and above ground to prevent soil-salt contamination.

The type of mortar used is also important. A brick may produce heavy deposits when one type of mortar is used but none at all with a different mortar. In general, however, a low alkali mortar will minimize salt deposits while one using Portland cement will increase the risk.

Keep concrete masonry away from direct contact with water and moist soil. During dry weather, evaporation will prevent there being a problem, but during humid weather, you may get deposits if your masonry is touching wet, “salty” soil.

How Can I Eliminate Efflorescence?

GreenWorks suggests using only environmentally friendly methods to eliminate efflorescence and also well notes that this problem is easier to prevent than to remove. Yet, high-pressure water, special cleaning products provided by stone dealers, and even muriatic acid can be used effectively. For the most stubborn “stains,” sandblasting and scrubbing with a hard-bristled brush may be necessary.

Having Trouble With Your Efflorescence?

Give GreenWorks a call. They are experienced at rooting out the cause of your efflorescence and can give you the answers you are looking for. Besides, they live at the cutting edge of where your home environment collides with the natural one and are experts at using simple, sound science to create affordable solutions to just about any environmental issue.

Posted on: June 19, 2015

Last Updated: June 7, 2020