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Mold Behind Pictures on Wall

Q. I noticed recently that on the West and North walls of my house I had mold growing only behind artwork I had hanging on the walls. These are both exterior walls (not basement walls) and I had no mold behind the artwork on the interior walls. There are no signs of water leaking into my house, and the walls appear to be dry. The exterior is brick and the interior is finished drywall.

Do you have any idea what may be causing this mold growth behind my artwork and how I can eliminate the problem? I am truly puzzled.

A. The reason mold accumulates only behind pictures on the exterior walls is due to condensation caused by the interior of your home being cool with a relatively high humidity level and the exterior being warm during the summer months. It works in exactly the same way that a glass of ice water sweats while sitting on the kitchen counter. Plus, the hanging picture restricts air movement which causes the space behind the picture to remain moist, and this is the ideal breeding ground for mold and mildew.

This is a common occurrence on solid masonry structures, or structures that are poorly insulated. The interior walls do not show these symptoms because everything inside is of uniform temperature so no condensation occurs.

Prevent Mold & Mildew Growth

If your display or storage space is particularly prone to mold growth, consider the following:

• Air circulation minimizes mold growth. Paintings or any artworks hanging on the wall should therefore have a spacer behind them so that they are not in direct contact with the wall. External walls, in particular, transfer dampness from outside.

• Keep the fans on, especially at night, not just for your comfort but for your artworks’ benefit. Highest levels of humidity are reached during the early hours of the morning.

• Avoid placing objects in the corners of rooms because there is naturally less air circulation in corners.

• Maintain a clean environment by vacuuming to prevent dust, because mold settles and thrives on dust.

• Regularly inspect artworks for signs of mold and remove it immediately.

If you have a persistent mold problem, you may have to “disinfect” the room before taking any of the above steps.

If mold is growing in particular areas of the building or room, even during the dry season, it usually indicates the presence of localized high humidity which may be caused by faulty plumbing, improper exterior wall coverings or improper flashing. Any of these factors will allow the wall to collect moisture and can create additional mold issues.

All of the above are measures to try and minimize mold growth, but they cannot guarantee outbreaks won’t occur. Hopefully, they will contribute to protecting your valued artworks.

Learn more about Mosby water & moisture repair services.

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