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Painting over Water Stains and Mold: How to Repair and Prep After a Water Leak

What is the rule of thumb for painting over water stains? I have a two-story house, and my second-floor shower stall developed a leak, as evidenced by water dripping from the first floor ceiling. The leak is small--a few drops of water after every use--and I believe I have now fixed the source of the leak (failing, cracked grout).

Now that I'm preparing to repair the ceiling, I see that the water dripped out around a nail head which developed a quarter-sized black stain that I assume is black mold. A few inches away, the paint has cracked and is peeling along a two-foot-long drywall seam. I was hoping to simply remove the loose paint, clean the black area with some bleach, re-spackle and re-paint the existing drywall.  Will this work or do you think that I should remove and replace the affected drywall to eliminate the black mold in the ceiling?

Our Answer

Before we get to painting over water stains, let's talk about mold. Mold needs three things to fester: air, food and water. While there is plenty of air and drywall is a terrific food for black mold, the fact that you have fixed the leak means that there should be no more moisture to feed a mold problem.
Secondly, the black mold that you think you have, may not in fact be black mold at all. While mold is possible, water stains--caused by the reaction of water with paper, paint and rust--can also form a black spot. Regardless, a quarter-sized area is nothing to worry about, even it is black mold, as long as the leak has been repaired.

As for painting over the water stain, my suggestion is to most certainly remove the loose paint as you suggested. Then wash the area down with a bleach-and-water solution just to make sure any mold spores have been neutralized. The next step is the most important: paint the stained area with an oil-based primer like KILZ. This will seal the stained surface and prevent it from leaching through to the top layer after you paint. For the best results, prime the entire area and not just the spots that have been impacted by the leak and resulting water stains.

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Is It Mold?

We've lived in our house for almost nine years, and have had a recurring problem in our central hallway. At one end, in which a few steps lead up to the master bedroom, dark (almost black) soot-looking stains have continuously formed on the ceiling and upper walls. On a couple of occasions I have partially (but not completely) removed these using a household cleaning agent and water. Then they form again! We've considered that this may be mold, except it doesn't look like any I'm familiar with. It looks like dirt or soot. We can't imagine where this may be coming from. Directly above is the entrance to our attic (a small removable panel) but no stains are forming on that, and it seems to be pretty well sealed. The only other explanation we can think of is we sleep with a floor fan turned on (mostly for white noise) and this might be blowing dust or dirt out into the hallway, which rises to the ceiling. Yet this doesn't seem like an adequate explanation either. Any ideas?

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Avoiding Mold

My classroom at school experienced a "flood" of sorts.  Water leaked in from windows 15 feet up on the wall, ran down the wall and soaked the entire carpet quite thoroughly.  My concern is how the school is addressing the clean up.  The water ran down the wall, but they are not removing the black boards to clean and dry the wall.  The carpet is on a slab, with no padding.  The excess water was removed, but no fans or dehumidifiers used to hasten the process.  Their plan is to simply clean the carpet.  

Am I right to be concerned that the carpet was never pulled up to dry?  What about mold build up underneath the carpet (even though it is a concrete floor).  What about mold growth behind the blackboard.

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Rain Barrels: Safe Against Mosquitoes?

I hear your discussion regarding the collection of rain water and would like to add that it is important to use a system that does not facilitate an explosion of mosquitoes. Mosquitoes are vectors which carry a number of diseases and it is important to control the population. Pls check out the Facebook page for Marin/Sonoma Mosquito & Vector Control District for examples of good and bad methods for collecting rainwater. The good methods make it difficult for mosquitoes to breed.

Our Answer

You make a valid point.  Standing water is an instant breeding ground for mosquitoes.  Even a small amount of water, like an overturned soft drink cap, can collect enough water for a mosquito to lay eggs. 

Most rainwater collection systems are covered, with the home's downspouts depositing roof runoff directly into the barrel, leaving no exposed standing water.  The rain barrels often have a spout or spigot to which you can attach a garden hose to when it's time to use the water for your grass, plants or garden.

More worrisome than a rain barrel are the objects that often collect in a home's backyard, like pool and sand toys.  These items can collect rainwater as well... and if not emptied regularly, can become a breeding ground for disease-carrying mosquitoes.

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Attic Mold: How to Determine the Source of the Black Mold

There's black mold in the attic of my three-year-old house. How can I tell if the builder used contaminated lumber?

Our Answer

Mold is common in attics. If you look at the black mold, you should be able to tell whether it was on the wood to begin with or grew after the house was built. If the rafters have black colonies on them, the wood was most likely contaminated to begin with.
According to The Money Pit's indoor air quality expert, Jeff May, in cold climates, if the sheathing is darkest on the north- or east-facing gable (worse near the outer, lower part of the sheathing), or if the attic mold appears only at the top of the rafters, the attic mold may be growing due to excess moisture, most often caused by improperly vented bathroom exhausts and leaky attic accesses that allow warm, moist house air into the attic.
But if you see oval- or other-shaped colonies that appear to be covered and bisected by rafters, the sheathing may have been moldy when installed.
For more tips on black mold and mold proofing your home, see our Mold Resource Guide.

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Mold on Clothing: When Mold Spores Attach

We stayed for a few days in a relative's house, and when we came back, our clothes smelled moldy. Can mold be carried from place to place on clothing?

Our Answer

Mold odors can be pervasive, even though the mold growth may be limited in scope.  According to The Money Pit's indoor air quality expert, Jeff May, despite the strong odor,  there may not be any mold spores on your clothing. If, on the other hand, the mold growth in the house was disturbed (if you sat on a moldy couch or rug), your clothing may be carrying spores and even mold-eating mites.
This isn't that different from getting pollen or pet dander on your clothing, and you can wash or dry-clean your clothing to remove them. Figuring out the source of the moldy smell in your relative's house is another matter!

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Mold and Real Estate: Musty odor is warning sign for mold issues

I am considering buying a house, but every time I visit the property, as soon as I get inside the front door I notice a distinct "moldy" smell. This goes away after a few minutes as I get used to it. Is it possible to fix this problem?

Our Answer

If you or anyone in your family is sensitized to mold, we'd be very cautious about purchasing a house with a musty odor, since you don't know the potential extent of any mold growth present. I'd also be cautious about buying a house in which the owner burns scented candles or has plug-in fragrance emitters, which may be masking a musty smell.
According to The Money Pit's indoor air quality expert, Jeff May, it's possible that the steps you could take to combat the mold would be very simple, but it's also possible that there could be a major concealed mold problem, and that any remediation required would be extensive and costly.
The most prudent thing to do would be to try to determine the source of the mold odor before you purchase the house. This could mean making holes in the walls to investigate possible sources of mold.

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Toxic Black Mold: Mold species that are harmful to human health

What exactly is that dreaded "toxic black mold" that seems to be in the news a lot?

Our Answer

Toxic black mold is a name given to a type of black mold technically known as Stachybotrys chartarum.  According to The Money Pit's indoor air quality expert, Jeff May, this type of mold is often referred to as "toxic black mold" because it's black, and under certain conditions, this type of microfungus, along with others, such as species of Aspergillus and Fusarium molds, can produce mycotoxins which have an impact on human health.
Other kinds of molds can be black, too, including Cladosporium mold, the most common mold, and "toxic black molds" produce mycotoxins only under certain conditions, and not all the time.
Stachybotrys chartarum is not as much as a concerns and another species of Aspergillus mold, for several reasons. Stachybotrys chartarum requires wet conditions (steady leaks or a floor flood) in order to thrive, and thus is not as common as Aspergillus molds, which can grow in conditions of elevated relative humidity. And Aspergillus spores are smaller than Stachybotrys spores, and thus can remain airborne longer and easier to breath.
Worrying excessively about toxic black mold also takes the focus away from what is considered a greater threat: mold allergens that, in general, can affect those who are sensitized.

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Mold or Algae?: How to determine the difference

There's green staining on the outside of my house. Could this be mold? And could it spread indoors?

Our Answer

If it's the color of plant leaves (chlorophyll green), what you describe is most likely algae or moss and not a concern (except cosmetic, perhaps). However, if you have mushrooms growing on the exterior siding of your house, hire a building investigator pronto! The growth will not spread indoors.

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Mold vs. Soot Stains: How to Tell the Difference: Soot stains on interior walls can be mistaken for mold

There are vertical, black stripes all over the insides of the exterior walls of my house. I'm sure it's mold. How do I get rid of it?

Our Answer

What you describe is most likely soot, which deposits on the walls in stripes where framing studs are located, in a flame-like pattern above baseboard convectors, in dots where nails are located, or as circular stains on ceilings above light fixtures.
You can test the stain by rubbing it with a little bleach on a paper towel; if the black color remains, it's soot, and if the color goes away, it's mold. Repaint soot-stained walls and avoid burning jar candles, which can emit a lot of soot, particularly after the candle has burned down about halfway.

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Mold, Dust and Fiberglass Insulation: Dust in insulation can grow mold

When my children romp around on the first floor of our house above the basement laundry, dust falls out of the exposed fiberglass insulation in the basement ceiling below. Is this something to worry about?

Our Answer

This could be a problem if your family has allergies and the dust is moldy or contains dander from a previous owner's pet. In addition, the fiberglass could be infested with mice or even with mold-eating mites--both sources of allergens that can find their way upstairs on air flows.
Fiberglass insulation makes for an excellent filter that can trap indoor air contaminants which can include dust that will feed mold.

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Mold on Concrete Block Walls: Determining source of fuzzy white growth on basement walls

There's a fuzzy white growth on my basement walls. Is that mold?

Our Answer

It may be mold but is more likely efflorescence, crystals of mineral deposits left behind when moisture migrates through a foundation wall, and then evaporates.
Efflorescence flakes will dissolve in vinegar or dry up into powder, which mold will not.
To reduce moisture on basement walls, improve your roof and surface drainage conditions outside the foundation wall area.

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Are Mold Test Kits Reliable?: Petri dish results often inaccurate and difficult to analyze

I decided to test for mold myself, so I bought a home mold test kit. The lab results came back saying there was penicillium mold in every room (the living room had eleven colonies) and a lot of stachybotrys mold in the bedroom. What do you think I should do next?

Our Answer

The kind of petri-dish (settle-plate) mold testing you refer to uses a small, flat dish containing a mold nutrient. The dish is supposed to be left open for a set period of time, then closed up and allowed to stand for several days, either in your home or, for an additional cost, in the lab to which you send the dish for analysis. Either you or the lab counts the colonies that grow.
The Money Pit's indoor air quality expert Jeff May doesn't trust the results of such tests, for a number of reasons. He notes that some people leave the dish open too long or run the test with the windows open, both of which can impact accuracy of the results.
Plus, the recent rapid increase in the number of consultants investigating mold problems and proliferation of laboratories providing analyses (and perhaps using unqualified technicians to do so) have led to many misleading reports.
May recommends that you next have mold testing done by professionals and the results analyzed by a qualified lab. If this second mold test confirms your original results, hire professionals to find and eradicate the sources of mold contamination under containment conditions.

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Mold Danger and Children

My three-year-old son has had a runny nose for the past year, and now has an eye allergy. His doctor said it could be due to mold in our apartment. We can't see any mold on the newly painted walls, but can smell and feel the humidity as soon as we walk in. The owner won't do anything about it, but I need to protect my son. I appreciate your advice.

Our Answer

Mold exposure can be very dangerous to children. The mold spores that lead to the health issues you've described are pretty speedy, stealthy airborne travelers, and can take up residence in areas of a home that aren't easy to spot.
 
Improper ventilation can lead to the damp environment that mold loves best, and this could be a primary issue in your apartment. However, an air quality professional will be able to give you the best and most thorough assessment of the conditions and what can be done.
 
Before finding a local pro through the Indoor Air Quality Association, make sure you've carefully documented any mold sightings and issues, as well as your son's pattern of symptoms. Then re-address the situation with your landlord, who has a duty to keep the property in a reasonable state of repair and safety.
 
If he or she still resists addressing the problem, be prepared to foot the bill for an air quality inspection, and to move or file suit if the results reveal mold issues that the landlord refuses to correct. Regardless, be sure that you have expressed your concerns to the landlord clearly and in writing. Should the landlord still not take action and the mold problem gets worse, the landlord could be responsible for not only the cost of cleanup, but even the cost of any medical treatments that exposure to mold may cause.

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Green Mold in Basement

Green mold is growing in my basement.  It is growng on furniture, boxes, plastic tubs, etc.  I am afraid to even check all my videos.  What is this mold?  My landlord is bringing in inspectors tomorrow.  My landlord said that I should not be storing anything in the basement. However, I have lived here in PA in this house for 18 months.  The flooring in the basement is concrete.  I have had previous mold exposure in CA when I lost my home. I have sealed all the vents from the basement to the first floor.  I am still getting sick.  What is this green mold?

Our Answer

I don't want to alarm you but this situation sounds pretty serious.  Although I can not be certain without seeing and confirming what you have with a lab report, my first guess would be that this green mold may be a potentially toxic mold called Aspergillus.
Under certain conditions, this type of microfungus, along with others, such as species of Stachybotrys chartarum (often referred to as "toxic black mold") can produce mycotoxins which have an impact on human health. Aspergillus mold can be more of a concern than Stachybotrys chartarum, though, for several reasons.
While Stachybotrys chartarum requires wet conditions (steady leaks or a floor flood) in order to thrive, and thus is not as common as Aspergillus molds, which can grow in conditions of elevated relative humidity. Aspergillus spores are also smaller than Stachybotrys spores, and thus can remain airborne longer and are easier to breath.
The photo above depicts Aspergillus and was supplied by Jeff May, author of The Mold Survival Guide and several other leading books on indoor air quality.  Jeff also authored much of The Money Pit's Mold Resource Guide .
In any event, a thorough, professional inspection by a mold expert is the appropriate first step to determining exactly what you have and what needs to be done about it.  Until then, hold tight.  One of the fastest ways to contaminate an entire house is by attempting to remove a serious mold infestation without having the knowledge, qualifications and tools to do so.