Mold/Possible Causation of White Mold near Floor?
Hello, and thank you for fielding my question, Steve.
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 1,000 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. These books remain in the same positions they were when they were originally placed upon the shelves. 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 removed 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.
Even though you don't see cracks or free water in the basement, I am sure that your basement has very high humidity levels for parts of the year.
I recommend that you remove all porous materials from the basement. They are probably loaded with mold. Carefully (to minimize spore release) place the books, etc. into strong plastic bags and discard. Install a high quality dehumidifier in the basement and run whenever the relative humidity in the basement exceeds 50%. This is typically during the spring, summer, and early fall. Use a wall-mounted humidistat to keep track.
If you have the funds, you should have a mold remediation contractor do the initial removal and cleaning work. They will use HEPA-filtered air scrubbers and/or negative air machines and HEPA vacuums during the work, and these measures will greatly reduce airborne spore levels and reduce spore deposition on surfaces.
The crawl spaces, if they are connected to the basement, are likely also contributing moisture to the spaces and to the house. You may even need two dehumidifiers. If you can drain the dehumidifiers into a condensate pump or a floor drain, they will not require daily emptying.
Best of luck, and let me know if you have any more questions.