White mold growth, while a common problem in residential homes, does not receive the same attention as the black mold. Primarily this is due to the fears surrounding more well known black molds, such as Stachybotrys. However, many white molds are still capable of producing negative health effects and should be dealt with promptly. Curious what kind of white mold you’re dealing with? Read up on mold testing before hiring a pro.

Common locations for white mold growth
Each type of mold has a preference for certain conditions. For example, Stachybotrys often prefers highly saturated materials, such as sheetrock after a flooding event. Because of these preferences, white mold growth is often found in the same location. Below are the most common areas.

Furniture
Mold growth on furniture is often white in color. Additionally, the mold typically has a 3 dimensional, fuzzy growth aspect.

Clothing & Textiles

Clothing, shoes, backpacks – when mold attacks contents within the home, it’s often white or light green in color. This is especially true for leather items. The good news? It’s easier to remove white mold than black mold. While the latter often leaves behind permanent stains, white mold can often be fully removed.

Attic sheathing and framing

White mold tends to grow in high humidity environments rather than areas suffering from total saturation. This is why it’s less common to see mold growth on base trim after a flooding event. The vast majority of attic mold is caused by humidity, which is why white mold growth is common here.

Crawlspaces

White mold is often found in two locations in a crawlspace, exposed soil and the lower portions of the floor joists. In cool climates, mold growth on floor joists is rare. But when it occurs, it’s often white in color.

In wet climates, exposed soil in a crawlspace will often propagate mold growth. Typically this is due to a missing or incomplete vapor barrier. The combination of an organic food source (dirt), excess moisture and limited airflow creates the perfect conditions for mold growth. In nearly all cases, white rather than black mold grows in the soil.

Does white mold lead to wood rot?

In short – no. Rot (dry rot, wet rot, white rot, brown rot) is caused by wood decay fungi. These are distinct from molds and are relatively small in number in comparison to molds. They require much higher levels of available water to grow. The name ‘dry rot’ is a complete misnomer, as all rot requires elevated quantities of moisture. If you find white mold growing on building material, it will not morph into rot.

However, this doesn’t mean your wood won’t rot. If you have a high quantity of moisture, eventually wood decay fungi will take over. This will happen regardless of whether or not you had any mold growing beforehand.

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

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.

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 sheetrock 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.

Can a color be used to identify the type of mold?

You cannot positively determine the exact type of mold based on the color. To determine the specific type of mold, you’ll need mold testing. However, color can be used to rule out certain types of mold. For example, Stachybotrys is always black. If you find white mold growth on a pair of shoes, you can rest assured it is not Stachybotrys. The same is true of chromium and a number of other mold types.

Unfortunately, many types of mold such as Cladosporium and Penicillium/Aspergillus come in a variety of colors. These molds can appear in everything from white or green to brown and black. This limits our ability to determine the exact type of mold by simply assessing its color. To fully identify the species or genus of the mold a sample must be collected and sent to a lab for analysis.

A tape lift sample is often the best method for determining the type of mold growth. In the photo below a sample of white mold is being taken from attic sheathing. Lab testing determined the growth was Acremonium.

Tape lift sample of white mold growing in the attic.
Tape lift sample of white mold growth.

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 mold 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’s 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.