White Mold or Efflorescence in Basements and Crawl Spaces

White Mold or Efflorescence in Basements and Crawl Spaces

Home Inspector Found White Powder on Walls
Efflorescence is a pretty common thing in wet crawl spaces and basements, but generally it is a harmless to people but may be a sign of a waterproofing problem. It most likely will not damage the surface where it is formed but may be a red flag during a home inspection.

What is Efflorescence?
Efflorescence is powder-like, white mineralized substance which forms on cinderblock and concrete walls over extended periods of time that are exposed to hydrostatic pressure.

hydrostatic pressure. (hī’drə-stāt’ĭk) The pressure exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity. Hydrostatic pressure increases in proportion to depth measured from the surface because of the increasing weight of fluid exerting downward force from above.

Efflorescence is usually made up from calcite and gypsum. It can also be seen on ground floors and it can sometimes look like foam. Efflorescence comes from aggregates, water, cements or admixtures and comes through the small cracks in the concrete or cinderblock. When the concrete and block are exposed to moisture, usually the efflorescence starts forming relatively fast. It usually forms in places with high humidity levels, such as basements and crawl spaces. Efflorescence is often mistaken for white mold, but it is not mold.

Is Efflorescence a Type of White Mold?
When in a crawl space or basement it may be hard to distinguish between efflorescence and mold without performing a mold test but true efflorescence is not mold. Now, what do I mean by true efflorescence? Sometimes efflorescence can grow on painted walls and the paint may support mold growth. When in doubt perform a surface mold test and send to a mold analysis laboratory to be sure you aren’t dealing with mold.

What to do about Efflorescence?
As stated earlier, efflorescence is usually a sign that there is a water leak somewhere in the foundation. Increased levels of moisture in your basement or crawl space may be an indication of some structural damage or that the exterior membrane has failed in some way. For example, water is picking up different kind of acids when it penetrates through the soil. Soil around house is generally acidic and that makes plants to grow. Concrete, on the other hand, is made of gravel, lime and sand. Lime glues the gravel and sand together. When water goes over the concrete it weakens the structure because the lime starts to break down. This ignites the chemical reaction which produces the efflorescence. So, making sure your outer waterproofing membrane is intact and working properly is the best way to handle basement waterproofing.

But, addressing water issues from the outside is not always doable either from a financial stand point or accessibility. If waterproofing the basement or crawl space is not attainable from the outside then an interior waterproofing system is a great way to handle the problem.

Efflorescence is a sure sign that you have water or leaking problem in the basement. If you notice something like this in your basement it may be a good idea to consult a professional to help solve the problem. Click here to read more:

Can Efflorescence Cause Mold?
An active water intrusion that is causing efflorescence is also causing humidity. Humidity over 60% can cause mold to grow on secondary areas inside the basement or crawl space like floor joists, subfloors or items being stored. Controlling humidity is crucial to ensuring a healthy home.

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Michael Church, Crawl Space Ninja
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