White Mold Identification and Treatment
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 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.
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.
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 a 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 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.
Can 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, the 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 chaetomium 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 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.
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 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.
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Your Questions – Our Answers
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I'm in a bungalow with 7month old twins. There is mold on every wall, most are black but one wall is whit and it is a fungal type growth on top of the wallpaper, it looks like rounded lumps of cotton wool. It's privately rented' what is it and what should i do?
If mold growth is visible on every wall, you’re likely dealing with a humidity based problem. This occurs when a home has insufficient ventilation. If the home has poorly insulated walls, the problem will be more severe. Due to the severity of the mold growth, I recommend calling a local professional (but watch out for opportunist who overcharge). In the meantime, I recommend improving your ventilation by running your bathroom exhaust fan 24/7 and cracking a window if possible. This will reduce condensation throughout the home. If the bathroom does not have an exhaust fan, install a Panasonic WhisperGreen fan.
Will painting concrete keep efflorescence from coming back?
If the problem is fairly mild, painting the concrete will reduce or greatly slow down the return of the issue. However, if the problem is substantial, the vapor movement will cause the paint to bubble and peel. Make sure you use clean and prep the wall and use a paint specially formulated for concrete. Specialty coatings designed to stop vapor movement do exist, but they typically work best on new concrete.
It’s always best to begin with an investigation of the moisture source. For example, check the downspouts above to ensure the water is directed away from the concrete wall.
Does bleach kill mold?
Yes, bleach can effectively kill/disable mold on hard surfaces. See this study. However, bleach has several negative characteristics (stains materials, unhealthy for humans, etc.) Therefore, mold remediation professionals often use alternative chemicals such as quaternary ammonium compounds. Organic, plant based chemicals such as Benefect are effective as well.
How do you clean the white mold off and keep it off? It’s on the bottom of wood doors and trim and cabinets.
It’s critical you first identify the cause of the mold. Without addressing the underlying moisture source, the mold growth will return. No chemical can prevent mold growth if elevated moisture is present. In time, the mold will simply grow on top of the new dust that settles on top of the cleaner/coating.
Assuming the area of mold growth is fairly small, the mold growth can be scrubbed off with a detergent/water solution. More powerful chemicals, such as bleach or quaternary ammomium compounds are necessary to kill the mold. However, because you’re physically removing the mold by scrubbing and wiping, the killing power of the cleaner is not necessary. White mold growth can typically be removed without leaving lingering staining. If staining is visible after scrubbing, you’ll have to sand and refinish the material to address the discoloration.
My father passed away recently. There are several antique pieces in his 70 year old home that I would prefer to keep. If I remove the mold with CLR Mold and Mildew remover, is it safe to bring them into my 20 year old house that is not experiencing any mold issues?
Yes, if you thoroughly remove the mold spores, there should be no danger in bringing the items into your home. After cleaning, you might see residual staining on the items. Staining is much more likely to occur with black mold vs. white mold. This is not active growth and poses no health threat.
If the items are non-porous, such as wood, plastic, etc. the cleaning should be fairly straightforward. Heavy scrubbing is not needed. Simply damp wipe the items with a cleaning agent. If the items are soft/porous, such as upholstered furniture, removing all the spores can be difficult. I would recommend a professional for the soft/porous items.
I found black mold all through my house. Is it safe to stay there?
There are two questions you need answered: 1. Is the mold growth currently affecting the air quality? 2. What is causing the mold growth?
If the mold growth is systemic, I recommend hiring a local company to inspect the home and collect an indoor air quality sample. 1-2 samples (non-viable) should be sufficient to determine the severity of the issue. Make sure they also evaluate the cause of the mold (i.e. high humidity, moisture intrusion, etc.) It’s critical you determine the cause of the excess moisture that is ultimately creating the mold growth.
In the interim, keep a few windows cracked open and run the bathroom exhaust fans 24/7. This will provide a constant influx of fresh air and lower the mold spore count while you investigate. If you have asthma or are experiencing other serious symptoms, contact your doctor immediately.
Just found white mold on my basement sofa and wall to wall carpeting only 1 year old. Brick exterior home.
The first step is to identify the moisture source. There are 3 possibilities. 1.) Vapor emissions from the concrete slab. This occurs when water vapor travels upward through the slab. It’s most common in older homes with missing vapor barriers. This can cause excess both moisture in the carpet and increased humidity in the air. The increased humidity can lead to mold growth on contents such as a sofa. 2.) Liquid water intrusions can have the same affect, but these are typically obvious (i.e. carpet is wet to the touch).
3.) The second possible cause is excess humidity due to poor ventilation and insufficient heat. Basements without adequate air flow and heat are prone to high humidity. Over time, this high humidity creates an environment conducive to mold growth.
Action steps: Purchase a relative humidity gauge and monitor the RH. Pull back the carpet in a corner and look for signs of water intrusion on the concrete and the carpet pad.
Will white mold cause rot in flooring such as sub flooring and floor joists?
Great question. Short answer = No, white mold will not cause rot.
Long Answer. Rot is caused by wood decay fungi. These are not considered molds and typically require much higher moisture levels to flourish. They also require much more time to grow. While mold can grow in a matter of days, wood decay typically requires months of saturation.
The prevention strategy is the same for both – get rid of the excess moisture.
While there are many thousands of types of mold, only a few types of fungi cause wood rot. If you observe white mold growing on your subfloor, that mold will not turn into wood decay fungi over time.
Our family just bought a bed online. It was delivered and on the headboard, there is some white fuzzy looking substances and we're a bit cautious. Is it possible to tell by the pictures?
Based on the photo, it certainly looks like white mold growth. If you need definitive proof, I recommend a tape lift sample kit.
I need to store my shoes in plastic shoe boxes due to lack of closet space. If I drilled holes in the boxes would this be enough to keep the humidity down?
You’re on the right track. Drilling holes will allow the shoes to breathe (as long as you don’t put them away wet). You’ll also need to ensure the closet does not have excess humidity. Make sure there is at least a 1/2″ air gap between the bottom of the door and floor/carpet. If it’s an older home with poorly insulated walls, you might need to keep the door cracked slightly to allow heat to enter the closet. If humidity still remains a concern, consider placing a Damp Rid unit such as this or this.
Hello, I have this white/cream colored grown all over my home and was wondering if it is a type off mold. No one (my landlord, spouse, children, neighbors) believe that
It’s difficult to fully confirm from the photo. Does it have a fuzzy appearance? Does it wipe off with damp paper towel? If yes, it’s likely mold. If it is crusty or difficult to wipe, it is not mold. I recommend a tape lift style test to confirm whether it is mold. If the test is positive, hire a local inspector to identify the source of the moisture. Systemic mold growth like this is usually due to humidity. Buy an RH gauge and try to maintain <50% throughout the home.
After many years of having this wall I’ve noticed this white fuzzy stuff on the paint. This is a decorated painted wall in my hallway, my shower is behind this wall. Could this be coming from a leak of some sort from shower? Here are some pictures.
Yes, this looks like mold growth. Especially considering there is plumbing on the other side of the sheetrock. We can rule out condensation, because it’s an interior wall. I recommend checking the wall with a moisture meter. If it’s above 20% M/C you likely have a leak. Next, you’ll need to determine if it’s due to a supply line, drain line or shower surround failure.
I was up in my attic and I saw this. Is this mold?
Yes, that is very likely mold growth. The amount shown in the photo is fairly minimal and would not cause structural degradation. If the mold growth is systemic throughout large portions of the attic, it’s likely due to an ongoing condensation issue. If it’s only in a limited area, it might be due to the original construction or a past, one time incident (mold doesn’t fade with time).
If the mold growth is systemic, I recommend evaluating the ventilation (ridge and soffit). Also, check for disconnected bath fan ducts and a lack of air sealing on the ceiling.
Hi, this has appeared growing out of the holes in my air brick. Do you know what it could be? Thanks.
This looks like blown-in fiberglass insulation (efflorescence would dissolve with water and mold wouldn’t have this kind of structure). It’s pretty unusual to see insulation forced through a vented brick. Was the wall recently retrofitted with insulation? If so, the process might have forced insulation through the holes.
Hi, the attached image is of a growth on an interior hallway wall next to a doorway. It has been there for a while and the last time I redecorated about 6 months ago I chipped out this corner, refilled it and decorated. However it is back. It doesn't smell and this is the only place in the house that it exists. The house has suffered from condensation in the past but since I installed a PIV unit we get no condensation any more. Any idea what this may be? Thank you
This is a bit strange. It certainly looks like distortion caused by a water intrusion. Condensation would not occur on an interior wall. Therefore the water must be coming from a liquid source (roof/ plumbing leak, etc.) I recommend renting or borrowing a moisture meter to verify the presence of water and trace the pathway to the source. If there is a bathroom above this area, check around the toilet and shower with a moisture meter. If it’s the top floor, check the attic for a roof leak.
This is a internal wall in a prefabricated built bungalow . No water pipes on this wall. It is a plasterboard wall. Could it be rising damp?
Rising damp (capillary action) will only occur if this wall sits on a concrete slab. If there is a crawl space below this floor, you’re not dealing with capillary action. You’ll need a moisture meter to verify the moisture source. These can often be rented at local construction rental shops. If it’s dry, the mold is likely due to damp materials during the original construction of the wall. Because it’s an interior wall, condensation is unlikely unless the interior RH is extremely high. If it’s wet (and there’s truly no plumbing in the wall), you might have a roof leak. Though rare, I’ve certainly observed roof leaks traveling down walls without leaving obvious damage on the ceiling.
I cannot see mould or damp on any walls nor solid wood floors of my 102 year old house, however black footwear both plastic & leather have a white film (like dust/powder) on them. Is this mould?
Assuming the shoes are stored in a closet, it is likely mold growth. White mold growth on shoes is nearly always due to high humidity. Closets in an older home often suffer from elevated humidity due to the lack of air flow and heat, combined with poorly insulated exterior walls. Keeping the closet door slightly open is often enough to solve the issue. This will allow heat to enter the area and moisture to escape. You can also assist the dry out by installing a moisture absorbing material such as Damp Rid.
Recently brought home boot molds that were exposed to NE flooding. Trying to save them. I see tiny amounts of white on them. White mold? They have not changed since brought home 4 days ago. We brought them into our basement. Was this a dumb move? Any way to save them?
They can be salvaged, but it will require heavy cleaning. First, treat them with a mildicide such as Benefect. After this dries, vacuum any 3 dimensional growth (do this outside – as some spores will make it through the filter). Lastly, lightly sand the wood to remove any lingering mold staining. Wear a mask during the cleaning to minimize your exposure.
does white mold turn brown when it dies?
No, the color of the mold does not change. Instead of describing it as ‘dying’ we categorize it as active vs. inactive. When moisture is removed from the area, the mold goes dormant/inactive. Much like a seed, it can regrow once moisture returns to the area.
I recently renovated a bathroom. There is new sheetrock, plaster and paint. In this one area, the wall started bubbling. When we chipped away at the loose paint there was white "stuff" that grows back when removed. This wall is next to the tub/shower. Is this mold? What should I do?
This doesn’t look like mold growth. It appears to be deformation of the mud/plaster due to excess water. I recommend investigating further with a moisture meter. Your goal is to identify whether the water is 1.) Entering the wall from the backside (is there plumbing in this wall?) 2.) Occurring due to splashing water during shower usage, or 3.) Excessively wet mud/plaster was used during the install and is deteriorating as it dries out.
If it’s the latter option, the moisture meter should show lower moisture content levels with each passing day.
Hi we having been smelling a moldy mildew smell for about5 months when we looking at the crawl space the entire bottom dirt was covered in mold white tat is what should we do the smell comes in the the heater vents really bad.
Mold growth on exposed soil in the crawl space is common. This is why it’s critical to completely cover the soil with 6mil poly sheeting. This will prevent any mold spores (and odors) from entering the home. I also recommend air sealing any penetrations in the crawl space/subfloor. This will greatly reduce the amount of air flowing up from the crawl space into the home. By most estimates, 35% of the air in the main portion of your home comes directly from the crawl space.