Mouldy Window Frames – What Causes Them and Steps You Can Take to Reduce Mould Build-Up

Posted: 28th July 2023

If you’ve noticed a fuzzy or splotchy substance growing on your window frames, you’re dealing with a common household issue: mould. Mould on window frames is not only unsightly, but it can also cause structural damage and pose health risks. Understanding the causes and knowing how to prevent and control its growth is crucial.

The Root of the Problem: Understanding the Causes

The primary culprit behind mould growth is moisture, and your windows, especially on the inside, provide an ideal environment for mould spores to thrive. Here are the main causes:

Condensation: Condensation occurs when warm, moist air comes into contact with a cold surface, like your window glass. This causes water droplets to form and often settle on your window frames, providing a damp environment perfect for mould growth.

Leaking Windows: If your windows are not sealed properly or the sealant around your window frame is broken, water can seep into your interiors. This dampness encourages the growth of mould around your window frames.

Poor Ventilation: A room with poor ventilation traps moist air, leading to a humid environment. Bathrooms, kitchens, and laundry rooms are particularly susceptible due to the excess moisture from cooking, washing, and bathing.

Which types of windows are more susceptible to mould build-up?

Mould can potentially develop on any type of window if the conditions are right. However, certain factors can make some windows more susceptible than others:

Single-Pane Windows: Single-pane windows are more susceptible to mould growth because they lack the insulation provided by double or triple-pane windows. The exterior cold easily affects the interior pane’s temperature, leading to condensation when warm interior air contacts the cold surface of the glass. This condensation can then promote mould growth.

Wooden Frames: Wooden frames, while not particularly prone to condensation, can absorb moisture if not properly sealed or if the sealant has worn off. This makes them potentially more susceptible to mould than vinyl or fibreglass frames, which are more water-resistant and less likely to foster mould growth.

Poorly-Sealed Windows: Regardless of the type of window, if they are poorly sealed, they can allow moisture to seep in from the outside, creating a damp environment conducive to mould growth.

Windows in High-Humidity Rooms: Windows located in high-humidity rooms such as bathrooms, kitchens, or laundry rooms are more likely to develop mould. The excess moisture in these rooms from cooking, washing, showering, etc., can lead to a buildup of condensation on windows, promoting mould growth.

Old Windows: Older windows can become susceptible to mould due to wear and tear over time. The seals may deteriorate, allowing moisture to seep in. Older wooden windows may have absorbed moisture over the years, and the paint or finish may have worn off, leaving the wood exposed to potential mould growth.

Tackling the Mould Menace: Prevention and Control

The key to mould prevention and control lies in addressing the moisture issue. Here are practical steps you can take:

Promote Ventilation: Proper ventilation is vital in reducing indoor humidity. Install exhaust fans in high-humidity areas like bathrooms and kitchens. Regularly open windows in other rooms to allow fresh air in and stale, moist air out.

Use a Dehumidifier: A dehumidifier can help in high humidity conditions by reducing the moisture level in the air, making your home less mould-friendly. This is especially useful in basements and other areas prone to dampness.

Regular Cleaning: Regularly clean your windows with a mould-killing solution. This removes mould spores before they have a chance to grow.

Insulate Your Windows: Proper insulation of your windows can help reduce condensation. The goal is to keep the window surface temperature from getting significantly cooler than the room air temperature. This can be achieved through thermal or double-glazed windows, which have insulating properties.

Fix Leaks: Regularly check your windows for leaks. If your window frames are wooden, look for signs of water damage or rot. If you find any, fix them promptly to avoid creating a hospitable environment for mould.

The Mould Removal Process

If mould has already made its way onto your window frames, don’t despair. You can remove it using a simple process:

Don protective gear: Wear gloves, a mask, and eye protection to avoid exposure to mould spores.

Make a cleaning solution: Mix one part bleach with three parts warm water.

Scrub the mould: Using a stiff-bristled brush, scrub the mouldy area with the cleaning solution until the mould is gone.

Dry the area: Once you’ve cleaned away the mould, use a dry cloth to wipe the area clean. Leave the windows open to dry completely.

Remember, if mould has penetrated deeper into the window frame material or the infestation is too large, you may need to replace the window frame or seek help from professionals.

Bringing it all together

Mould on window frames is a problem that, while common, shouldn’t be ignored due to its potential health risks and potential to cause structural damage. Regular inspections and cleanliness, along with controlling indoor moisture, can prevent the growth of mould. Take steps today to protect your windows and ensure a healthier, more comfortable living space.