Mold on Window Sills

How Did I Get Mold?

Molds reproduce by means of tiny spores. The spores are invisible to the naked eye and float through the air. Mold may begin growing in your home when spores land on moist organic material surfaces such as wood, drywall and other materials. All types of molds require moisture for growth. Molds grow best in warm, damp, and humid conditions and spread and reproduce by making spores. Molds can grow on the grease or any other organic substance such as a dust or a dirt layer, commonly found on window sills.

How To Prevent Mold

Prevent the growth of molds by preventing excessive moisture in your home. Molds require 24 to 48 hours of moisture to begin to grow. Therefore, if your window sills in your home are wet for more than 24 hours or so, you run the risk of the growth of molds. Indoor relative humidity (RH) should be kept below 60 percent, ideally between 30 and 50 percent, if possible.

Steps to prevent the growth of molds:
      • Wipe your window sills when they are wet from condensation
      • Purchase triple pane glass in high moisture areas such as bathrooms
      • Reduce condensation – see preventing “Condensation” webpage
      • Minimize mold by cleaning and dusting your window sills as the spores can enter your home through an open window

Removing Mold

Once molds have begun to grow in your home, sometimes it's not enough to just take away the mold's moisture source by wiping it off with a cloth. Mold that runs out of moisture and is left behind can lie dormant for a long period of time without dying. So if you already have mold growth on your window sills, you need to take steps to remove it correctly.

Here are a few easy steps to remove molds:
      • Fill a spray bottle with white vinegar (do not add water)
      • Wear non-porous gloves when cleaning with vinegar
      • Spray the vinegar on the troubled area
      • Allow the vinegar to sit for at least 1 hour
      • Scrub the molds away with warm water using a scrub brush or toothbrush
      • Wipe the surface with a dry clean cloth

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