Mold/Possible Causation of White Mold near Floor?
QUESTION: Hello, and thank you for fielding my question, Daniel.
I have an older one-floor house in New Jersey which has a main level and an unfinished basement with a concrete floor. It was constructed in the late 1800's. Approximately 50% of the house is built over the original basement. The newer additions, which were built in the mid 1900's, are constructed over concrete crawlspaces.
There is an apparent white mold problem which exists on the main level, yet only affects those areas of the original house that are directly above the original 500 sq. ft. basement. The mold develops on wooden surfaces up to a height of about four feet above the floor. It seems to flourish in warm humid weather.
Despite its age, the original basement is in excellent condition. There are no cracks in the foundation or the floor. The basement is not subject to flooding, water does not enter through the windows, and rainwater does not penetrate the concrete walls.
However, I do suspect there is a moisture issue which is causing the mold I am encountering. My question regards the cause.
When my grandparents purchased the home in the 1950s, they moved over 1,500 hardcover and softcover books and magazines printed in the 1920s and 1930s from their previous home and placed them upon shelves which are up against one wall of the basement. Many of them have become moldy and are damp to the touch. There is a pungent odor in the basement.
Additionally, for whatever reason, there was a piece of plywood laid upon the concrete floor. Whenever the plywood was stepped on, water would expel or splash from underneath the board. I moved the plywood board and found no cracks in the floor. Since removing the plywood, the floor remains dry. It seems that the wood laying on the floor encouraged moisture beneath it.
Is it possible that this literature collection is attracting dampness and moisture, thus encouraging mold in the basement and immediately above? I know that paper and wood, being fibrous, can absorb moisture, which is why I suspect the books and magazines.
Thank you for any thoughts you might offer on this matter.
ANSWER: H Alex, you have an interesting and historical situation. Any kind/color of mold needs air, moisture and a food source to be alive and grow. When it does that it "off gasses" the musty smell.Whatever books, wood and anything else in the basement must be removed. The entire basement must be treated with an "anti-microbial" treatment. Then it needs to dry out. After that I suggest installing a dehumidifier which should be set at 50% - 60% and left to run and drain automatically. Only then would you be able to store such items down there. Books don't attract mold but they are a food source for mold. Moisture can come through concrete because it is porous and that is why the plywood on the floor was so wet. It was trapping the moisture between the concrete floor and the underside of the plywood. If you store stuff down there again you would need to put something to raise whatever you are storing, off the concrete floor. Something made of plastic is better than anything made of wood. A metal storage type thing can rust so I don'r recommend that either. For more information you can look up mold on www.cdc.gov/mold or www.epa.gov/mold
Good luck, Daniel
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QUESTION: Hey Daniel,
Thank you for that very through reply. I must ask a follow-up question in regards to an important detail that I forgot to include in the original question.
During the summer, this basement feels very damp, and that dampness can likewise be felt in the rooms above it. On a very humid day, being in the house for ten minutes gives one the feeling of sweating. Air conditioning is not used. Upon leaving the house, there is a feeling of clamminess on the skin and a slight odor in the clothing and nasal passages. Note that this only occurs on days and nights when there is higher humidity.
I have often heard of damp basements, but my mom's house, which has a cracking basement floor, hardly ever experiences and dampness and no visible mold. Might it be the particular concrete that was used to build the basement which allows this moisture to penetrate so intensely?
You are correct about keeping any metal in such an environment; There are some old lamps and other metallic items stored in there which show signs of rust.
How do you mean that I have "an historical situation"? And, along with following the other sound advice you have provided, would the permanent removal of these books and other contributing items reduce the dampness in the basement?
Thank you very much for helping me to understand this issue better.
Hi Alex, By "historical situation" I mean the house is very old and was added onto over time. When there is high humidity in the air more mold will grow. When mold grows it "off gasses" that is what you smell and are breathing. All concrete is porous it does not matter what type of concrete it is. The ground around your mother's house must be dryer than the ground around your house. Thus allowing more moisture to enter the basement through the concrete. Proper ventilation and/or de-humidification is a key to having a dryer basement. By the way your mother's basemnt may also have mold in it you just can't see it. Some molds are actually invisible and some molds hide in the cracks in the floor or walls and other minute places in the basement. Did you check out the web sites that I sent to you? They have much more detailed information from experts that may help you with your situation.