hand on window handle

How to Clean Inside Double-Glazed Windows

The vast majority of UK homes have double-glazed windows. A double-glazed window is made up of two panes of glass held together with an airtight seal.

They can be pretty pricey, but they improve the insulation and energy efficiency of your home—arguably worth the price tag.

Although double-glazed windows are completely sealed when fitted, it is not uncommon for these seals to become damaged with time.

This allows condensation, dust, and dirt to accumulate between the panes of glass and obstruct your view of the outside.

Cleaning between these panes may seem impossible, but there are ways to remove this unwanted build-up.

In this article, you’ll learn how to clean inside double-glazed windows without the help of a professional. Read on for a comprehensive guide!


What’s the Best Way to Clean Inside Double-Glazed Windows?

professional replacing window seal

If you notice condensation, water droplets, dirt, or dust inside your double-glazed window, the best solution is to call a professional.

The murkiness inside your window is due to the seal breaking. A professional can reseal or replace your window to resolve the issue.

Unfortunately, this can be quite expensive, especially if several of your windows need to be fixed at the same time.

If you want to avoid these costs, there are a few things you can do to try and clear out the inside of the window and prolong the time before a professional needs to be called.

The best cleaning method involves drilling a hole in the glass. This allows you to insert a cleaner between the two panes and remove dirt and condensation.

It is the only effective method if you have dirt stuck between the two panels, but it does require basic DIY skills.

Fortunately, you can clean inside double-glazed windows without drilling if you aren’t confident using a drill.

However, this is only successful in removing moisture—not dirt. If you have dirt between your windows and don’t want to risk drilling the glass, calling a professional is your only option.


How to Clean Inside Double-Glazed Windows by Drilling Holes

professional drilling holes on window

If you want to remove dirt between the window panes, then your only option is to drill holes into the glass. This allows you to insert a cleaner into the holes and clean inside the two panes (see below).

However, drilling can cause your window to crack when done incorrectly, so we suggest you only do this as a last resort and if you’re comfortable using a drill.

If you’re up for the challenge, the safest way to drill these holes is as follows:

  1. Attach a 3/8-inch diameter glass cutting drill bit to a power drill.
  2. Fill a spray bottle with cold water.
  3. Put on a pair of safety glasses and some protective gloves.
  4. Place the drill tip in the bottom right corner of your window on the side that faces outdoors.
  5. Carefully drill into the glass while constantly spraying the area with cool water.
  6. Stop drilling as soon as the tip has gone cleanly through the exterior pane.
  7. If needed, repeat in the upper right corner of the window as well.
  8. Wipe down the glass to remove any remaining moisture.

Once you have finished drilling, you have a few different options for cleaning inside the two panels of your double-glazed windows.

The best choice depends on whether you’re trying to remove dirt, moisture, or both, and what equipment and ingredients you have to hand:

  • Wipe the glass clean: Create a long duster by securing a sock to the end of a wire. This can then be inserted into the hole and used to wipe away any dirt or moisture inside the glass. This method works best on smaller windows.
  • Inject a cleaning solution: Use a syringe to inject a cleaning solution into a hole at the top of your window. The liquid will run down the glass and remove some of the dirt. If you use this method, ensure you remove the excess liquid with one of the options below.
  • Insert a desiccant packet: To draw moisture out of the window, insert a small desiccant packet into one of the holes. Once all the condensation has been absorbed, you can remove the packet and discard it.
  • Use a fan to increase air flow: Aim a fan directly at your window to increase the airflow through the holes. This will help to evaporate any moisture and condensation trapped between the window panes.

After you have thoroughly cleaned your double-glazed window, ensure you leave the holes open. This will allow you to easily clean the window again and prevent any moisture currently between the panes from being locked inside.


How to Clean Inside Double-Glazed Windows Without Drilling Holes

clean double glazed window with dehumidifier

If you don’t feel confident enough to drill into your window, there are some things you can try to draw out moisture without creating any holes.

These methods will not be able to remove any accumulated dirt, but they will help remove any water droplets or condensation that may have formed.

  • Draw out moisture with a dehumidifier: Small dehumidifiers can be purchased for less than £100. When placed near your window, they will help to draw out some of the moisture inside.
  • Purchase a moisture absorber: Moisture absorbers can also be used to remove the built-up liquid inside your windows. These can be bought in the form of a water snake or a small plastic unit, such as the Unibond Aero 360.
  • Use a hairdryer: As a last resort, you can try evaporating the liquid inside your windows with a hairdryer. Always use the lowest heat setting and hold the hairdryer a safe distance from the glass, as too much heat could cause your windows to crack.

Remember that these solutions are only temporary fixes and may not leave your windows looking like new. If you have any concerns or wish for a more permanent solution, your only option is to call a professional.


Why Is the Inside of My Double-Glazing Cloudy?

Condensation on window

When a window is fitted, you don’t expect the inside to become clouded with condensation.

Unfortunately, this is a common issue with double-glazed windows and indicates a problem with the seal holding the glass panes together.

Moisture in the air can then accumulate inside the window, making it appear foggy.

There are several ways in which this seal can become damaged. The most common causes include:

  • Temperature fluctuations: As the temperature changes throughout the year, the glass within your window will expand and contract. This movement will not be noticeable but slowly take its toll on the seal, allowing cracks to form.
  • Poorly fitted windows: If your window became cloudy soon after it was fitted, it is likely that the glass panes and window frame were not properly aligned during installation. This increases the chance that the seal will break, allowing in unwanted moisture.
  • Incorrect cleaning products: Many cleaning products you can purchase from the store contain harsh chemicals that cause damage to double-glazing seals. In general, avoid products containing bleach and stick to natural cleaners for washing windows instead.


Is Condensation on the Inside of Double-Glazed Windows Bad?

condensation on glass window

If you notice condensation inside your windows, it’s a good idea to rectify the problem as soon as possible.

Although the cloudy appearance of the glass might not bother you too much, a number of other issues can arise when the water is left for a long period of time.

First, the condensation is a clear sign that the seal around your window has been broken. This decreases the window’s insulating properties, as air can more easily flow in and out of your home.

Unfortunately, your energy bills will increase as a result, especially in the cold winter months.

The other main issue related to the formation of condensation is that it can lead to the growth of black mould.

This is a serious health concern, especially in babies and young children. Not only can it make you feel generally unwell, but it can also trigger asthma attacks, cause nasty skin rashes, and may lead to life-threatening illnesses.

You’ll need to remove it quickly using a black mould cleaner.


How to Stop Condensation Inside Double Glazing

air vent and dehumidifier

If your home is particularly prone to condensation, there are some ways to reduce the humidity so that the water vapour is less likely to form. Your best options for this are:

  • Improve the ventilation: One of the best ways of reducing the humidity level in your home is to allow for proper ventilation. Although an appliance like an extractor fan will help with this, simply opening your windows will be highly effective. This may seem impossible during winter, but even 20 minutes a day will allow some of the humid air to escape your home.
  • Control the humidity: If your humidity levels are particularly bad, you can also try to control them. Dehumidifiers are a great way to do this, but they can be expensive if you want one to cover your whole house. Instead, try placing smaller ones in the rooms that tend to be the most humid (e.g., the kitchen and bathroom).