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White Mold

Identifying white mold growth in your home

White mold growth, while a common problem in residential homes, does not receive the same attention as black mold.  Primarily this is due to the inflated fears surrounding the toxic black mold, Stachybotrys.  The color of mold growth can rule out certain species, however it cannot be used to positively identify a species of mold.  For example, Stachybotrys is always black, however, Cladosporium and Penicillium / Aspergillus come in a variety of colors.  Additionally, many other species of mold besides Stachybotrys are black in color.

White mold growth on dresser

White mold growth on back side of dresser.

White mold growth provides an additional challenge because it is often confused with efflorescence, a crystalline growth structure found on concrete and masonry surfaces.  Efflorescence occurs when water moves through a masonry structure, bringing unbounded salts to the surface.  When the water evaporates, a white, fluffy structure is left behind.  This growth, while harmless, can appear very similar to white mold growth.

White mold can be found anywhere conditions conducive to mold growth are present.  Common areas of white mold growth include attic sheathing and crawlspace framing.

How can I tell the difference between white mold and efflorescence?

A trained mold inspector can readily determine if the growth structure is from white mold or efflorescence.  Additionally, efflorescence will typically dissolve under the application of a water mist, while mold growth will not.  Other helpful distinguishing characteristics include the material of the substrate.  Efflorescence will only occur on concrete, brick or other masonry structures.  If you find a white mold like substance on sheet rock or wood, you can certainly rule out efflorescence.  Another indication, though imperfect, is the presence of a mold smell.  Efflorescence is odorless, while mold growth often produces a musty odor.

Efflorescence on Concrete

Efflorescence on Concrete


Is white mold dangerous?

Many molds can provoke allergic responses in sensitive individuals.  No area of significant mold growth within the home should be considered safe.  Proper identification of the underlying cause, removal and cleanup should be performed regardless of the color of the mold growth.

What tests are used to identify white mold?

Direct sampling can be used to identify the species of white mold.  Types of direct sampling include tape lift, swab and bulk samples.  These samples are collected by a technician and sent to a laboratory for analysis.  The lab will first determine if the suspect growth is mold, and if so, what species of mold.

Are there any special concerns for mold remediation when dealing with white mold?

Your approach to mold cleanup should remain the same regardless of the color.  Remember, many types of molds, even non-toxic molds, are capable of causing an allergic response.  Because of this, the color of the mold is inconsequential.  Many non-allergenic molds are white, as are a number of allergenic molds.  Confusing the issue even more is the fact that we simply don’t know the allergenic capabilities of the vast majority of molds.  Conclusion = treat them all the same.

White mold growth inside an attic

White mold growth inside an attic