Mold on the window sill is a very common problem no matter if you live in a cold area or hot area, and have poor ventilation in your house. This problem not only makes your windows stained but also is the cause of many health risks.  
If you have mold on your window sills and frames you should remove that as soon as possible so that your windows don’t get more stained or cause respiratory problems or other types of infections.

In this article, we will be understanding about different types of mold, their causes, how to clean them, and their danger so that you can maintain a healthy living environment.

Causes Of Mold On Window Sills

Some factors that are the causes of Mold on window sills are the following:


Moisture is the main requirement that mold needs for its growth. High humidity, window leaks, damaged window frames, leaks on the roof, etc can be the cause of the moisture in your house and this can be the reason for the mold to grow on window sills or frames.

Poor Airflow

Lack of proper airflow can trap moisture in your home and that can create the best environment for the mold to grow.


Warm environments are also the cause of some types of mold. In some cases, if the window sill is exposed to direct sunlight constantly that can be the cause of mold growth.

Window Material

In some cases the window sill or frame is made out of organic material like wood etc and dust staying in that area can provide food sources for mold.

Types Of Molds On Window Sills

Molds have different types. Each type has different characteristics and could cause different types of problems. Those types are the following:

  1. Aspergillus: This type of mold is typically found indoors. It has different colors including green, yellow, and black. It grows on different surfaces and in wet environments that fall under the temperature of 53 F° to 149 F°.
  2. Cladosporium: Cladosporium is found indoors and in cool damp areas. It can appear in black, green, or brown colors. If mostly grown on organic materials i.e. wood, fabrics, textiles, and other materials.
  3. Penicillium: It is well known for its blue or green appearance. Penicillium usually grows on materials that might have been damaged by water including wallpapers, carpeting, insulation, etc.
  4. Stachybotrys: It appears in black or dark green color. Stachybotrys is commonly known as black mold. It is the most toxic mold out of all the indoor molds. It grows on materials like wood or paper.

You can learn about some other types of mold that might grow in your home.

How To Clean Mold From Window Sills

The steps to clean mold from window sills are following:

Step 1 – Wear Protective Gears

Wear safety gear such as gloves, masks, etc so that when you are cleaning mold it doesn’t touch your skin or go inside your lungs while breathing and cause infection or allergy.

Step 2 – Remove Excess Mold

Open the window from where you are cleaning the mold and remove the excessive mold that is on the surface. To remove the excessive mold, spray water on the surface and wipe that area with a dry cloth that you can easily throw away after cleaning.

Step 3 – Cleaning Solution

Some of the best cleaning solutions for mold are beach, vinegar, baking soda, Tea Tree oil, etc and after some research, we found that bleach is the best way to remove mold. But bleach mixed with water only kills mold that is present on the surface level and thus it can grow back.

The best cleaning solution is baking powder mixed with white vinegar. Spray this solution where the mold is and let it sit there for a few minutes so that it is soaked in that area where mold is growing and can fully kill the mold. 

Step 4 – Scrub

After applying the cleaning solution and letting it sit there for a few hours scrub that area with a brush or with a spine. Don’t scrub too hard that it might damage the surface but scrub enough that all the visible mold is removed.

Step 5 – Rinse

Rinse the area with clean water and dry the area using a cloth or paper tissues so that the mold doesn’t grow in that area again.

Step 6 – Disposal

Dispose of the cleaning materials that you use so that you can avoid spreading mold and any other health-related issues. Avoid touching the cloth, brush, or tissue paper that you have used to clean mold because that could cause you allergies and other health problems.

Dangers of Mold

In the start, mold might not appear as a very big problem but it can cause many health issues. It also damages the area where it is growing and can destroy your property and its value.

Health Issues

If you are exposed to mold constantly and you accidentally touch it or you are breathing near it it can cause health issues like respiratory problems, allergies, infection in your toenail, inflammation in the lungs, etc. 

Symptoms include coughing, sneezing, runny nose, and skin rashes.

Property Damage

Mold can easily damage and deteriorate organic materials like wood, paper, fabric, drywalls, etc. Over time these damages can lead to structural damage to your house. This looks very bad and also decreases the value of your property

Prevention Tips

To prevent mold on the window sill you would have to control the moisture and would also have to maintain a clean area around your windows. Some tips that can help you prevent mold are the following:

  1. Use dehumidifiers and air conditioners to keep the indoor humidity levels below %60.
  2. Install exhaust fans in areas where you cannot use air conditioners to increase airflow.
  3. Clean window sills and window frames regularly so that the dust does not stay there for a long time.
  4. If your house is leaking from somewhere or there is water constantly at some places in your house, fix it and try to keep that area as dry as possible.
  5. Use mold-resistant paints and sealants on the window sills and on the area around those places.


Mold on window sills is a manageable problem. You can easily control and remove the mold by understanding the type of mold and the damage that it might cause to the place. By removing mold using the cleaning steps explained above you can save yourself from health issues and your property from damage. 

After cleaning, you can easily maintain and clean that area to prevent mold growth in that area again.

A: Some types of molds are not toxic but others are very bad for your health like black mold. However, due to similarities between these types, it is hard to identify which mold is dangerous and which one doesn’t affect the human body.
Mostly window sill mold doesn’t cause many health issues but in some cases, it can also cause skin irritation and breathing issues.

A: It is very normal for mold to grow around areas like window sills, leaked areas in the house, water pipes, and areas that are exposed to water or constant sunlight.

A: Mold can be very harmful for you so it is recommended to remove it as soon as possible.

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