Efflorescence

The ugly white, brown or green salty looking substance you observe on masonry walls. Efflorescence shows up outside on retaining walls, basement foundations, brick veneer, chimneys and inside on basement walls, fireplace fronts, brick kitchen walls, etc. If you haven't seen it, you aren't paying attention or you haven't looked at many homes, and are assured that you will see it soon.

What is it?

Efflorescence is a crystalline deposit of water-soluble salts. For these deposits to form on masonry surfaces, there must be a source of salt, and water to move the salt. For this condition to exist, the following conditions must exist:
1. There must be soluble salts in the wall.
2. There must be a source of water that comes in contact with the salts and forms a salts solution.
3. There must be a pathway for the salt solution to migrate to a surface and evaporate.
It is virtually impossible to construct a masonry wall without some soluble salts and water in the wall. Therefore, the potential for efflorescence exists in all masonry structures.

Why is it there?

Many of the materials used in and around construction contain soluble salts. Some of them include: mortar, concrete, concrete block, grout, brick, brick-mortar reactions, contaminated water, contaminated mortar sand, mortar additives, fertilizers, deicing salt, acid rain, cleaning chemicals.

Water is contributed by these sources:

During construction - by mortar, concrete, grout, cleaning, and rain (construction water can take months or years to totally evaporate from the wall surface, depending on climate and wall orientation.)

After construction - by condensation within the wall and by leaks through mortar joints, cracks, control joints, expansion joints, isolation joints, wall copings, chimney caps, and around window and door openings.

Salt solutions must migrate to the evaporation surface to create efflorescence. Water already in the wall from construction, or entering the wall from whatever source after construction comes in contact with soluble salt and forms a salt solution. The salt solution migrates to the surface of the wall, evaporates leaving the efflorescence.

What does it mean?

Efflorescence is ugly, but its unsightly appearance usually has no effect on masonry's structural integrity or durability. Efflorescence is seldom desirable. But in older buildings it can serve as a cry for help, indicating and helping pinpoint water intrusion. The problem should be addressed as soon as possible to avoid more serious problems, such as basement leaks, corrosion and freeze-thaw damage.

It the structure is less than a year old, it is possible that "new building bloom" is the culprit. In most cases this problem will go away on its own when the construction dries out. Remedial cleaning efforts are a waste of time until the wall has dried out. Rain usually will wash away these highly soluble salts.

If the structure is older, water is the culprit. You must determine the source of the water and stop it to stop the efflorescence.

What can be done about it?

A basic understanding of its causes can lead to preventative measures and can aid in the elimination of the problem. Efflorescence can be removed from the wall with proper cleaning techniques and, in most cases, will take care of itself with time.

Lines of defense during construction are provided by:

Good material selection
Proper design of flashing, weep holes, cavities, and copings
Good workmanship: filling all head and bed joints, providing flashing and weep holes that drain, keeping cavities clean, covering walls as they are built, and properly cleaning the wall at the conclusion of construction

Lines of defense after construction are provided by:

There are two ways to stop efflorescence. Take away the salt or stop the water. It is impractical to remove the source of salt from the wall. The prudent action is to remove the source of water. Correction of any construction deficiencies, which are allowing water to infiltrate the wall, and regular and knowledgeable maintenance will stop the efflorescence.

Large portions of this article, although the author has extensive experience with the subject, were influenced by and borrowed from "Everything Efflorescent" by Harold B. Newman, Vice President of technical services for Pine Hall Brick Co., Madison, N.C. published in the September 2000 Issue of Masonry Construction.

Thought for the week

Sometimes the people you expect to kick you when you're down will be the ones to help you get back up,
and the ones you expected to help you up are sitting on top of you.