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Preventing Mold on Windowsills

Preventing Mold on Windowsills

Finding mold growing on a windowsill can be unsettling. While no cause for immediate alarm, mold in the home can cause health issues for those living there.  It’s important to figure out what is causing its growth and make changes to prevent it.

Why Does Mold Grow on Windows


A moist environment must exist for mold to grow. This can be caused by a couple of different factors, including internal and external issues.

Internal factors could include rooms where a lot of moisture is generated. Those factors include water boiling in a kitchen or a hot shower. Installing Window Air Conditioner and regularly using an exhaust fan alleviates most of these issues This is an easy fix.

External factors cannot be as easily solved.

What Causes Mold

The mold on your windowsill may come from condensation or leaks allowed into the house through your windows. This happens most often in winter when it drips down to the bottom of a window. To prevent more mold from growing, you must first decide where the moisture originates.

If you see condensation on a window, the first thing you must do is check for leaks. You may find one of the following issues:

Cracked caulk or sealant

Can Window Choice Prevent Mold

Window Choice Prevent Mold

Due to condensation, you may find water (moisture) around windows, which happens most often in the winter months. This water drips down to the bottom of the windows and affects the windowsill and the drywall around it leading to mold growth. Mold in a home can cause health problems if left unchecked.

Recaulking and weatherstripping may help block some of the moisture, but often window replacement is the only real solution. The choices you make about your new windows make a difference. Your window options consist of materials, like wood, vinyl, or aluminum, and style, like single or double hung, sliding, bow, bay, or casement windows, etc.  Let’s look at how window materials and construction make a difference in reducing moisture in your home:

  • Wood windows: Most older homes with windowsill mold problems still have their original wood windows. In these cases, the window frames may have flaking paint, crumbling caulk or single-pane glass, all of which allow moisture into the home. New-home builders who opt for wood windows get a better product, often with double-pane glass and other insulating upgrades. However, wood still expands and contracts as it absorbs moisture, requiring paint and other sealants be applied and maintained over time.
  • Aluminum windows: Homeowners often avoid choosing aluminum windows because they assume this material doesn’t offer as much insulation since metal conducts both heat and cold. Window Liquidators offers a line of aluminum windows from Crystal that addresses this issue. Crystal’s aluminum thermal-break windows provide an exceptional choice because of a polyurethane thermal barrier that effectively “breaks” conduction turning the aluminum into a good insulator.
  • Vinyl windows: Though they can be expensive, vinyl windows offer the most energy-efficient option of the three to prevent moisture from seeping from outside into your home. Vinyl frames and sashes help reduce condensation on your windows, which also reduces the opportunity for mold to form on the windowsill. Because of vinyl’s natural insulating qualities, the temperature of your interior glass remains higher. Also, because of the insulation provided by these windows, the air surrounding the window remains warmer, which allows it to store more water vapor. This keeps the moisture off the windowsill creating a dryer environment.

Two product lines of vinyl windows are available from Window Liquidators. Learn more about the advantages of each on our site. 

Other Features That Help Prevent Windowsill Mold

Windowsill Mold

Glass choice makes a big difference in environments where moisture is a concern. Window Liquidators’ product catalog offers energy efficient choices that can help control moisture. Choosing windows with a glass package that includes at least a double pane design with argon gas between them provides extra protection against moisture and heat variances.

Order Replacement Windows

Sometimes the only way to rid your home of mold on the windowsills for the long term is to choose new replacement windows. Window Liquidators has a great selection of energy-efficient windows in many styles to suit your needs. Browse their products or get in touch to learn more.

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