Home OwnersCondensation


condensation on glass

Condensation on Windows

Misty bedroom windows and damp curtains are more than just minor wintertime annoyances. Condensation on window panes are often indicative of hidden problems that if left unchecked, can lead to major structural damage.

It may seem like condensation only happens in the winter because it is most noticeable on those frozen winter mornings. However, condensation can happen year-round, and it’s important to be on the lookout for wet window frames and damps spots around the house.

Are you wondering if condensation on your windows is really an issue? The answer is yes. Peeling or bubbling paint and warped wood surfaces are a sign of dampness. When unattended, this can lead to rot and may need expensive repairs.


What causes condensation on windows?

condensation on window frame

Condensation on glass and joinery is due to two things.

  1. The amount of moisture in the air
  2. The difference in temperature between the window/door and the air temperature

When a glass surface is cooler than the environment surrounding it, droplets of water collect on it. These droplets of water are called condensation. Simply put, for condensation to occur, humidity or moisture-laden air needs to meet a cold surface, like glass. At this point, it will turn into little liquid drops.

Condensation can collect on any glass surface, whether it’s on your glass of cool orange juice on a warm day or on the glass panes of your windows. The reason we see condensation most often on glass is because it is an impervious material that does not absorb water.

To reduce condensation we can either address one or both of these points.


How to stop condensation on windows:condensation on windows

In order to prevent condensate from forming on windows, you need to address the factors causing it including humidity in the environment, ventilation systems and the insulation of the building.

  1. Dehumidify the environment
  2. Increase the insulation of your windows
  3. Apply heating and reduce sources of moisture

1. Dehumidifying the environment

Having a good ventilation system removes excess moisture from the interiors of your home. Keeping the environment drier does reduce the chance of condensation.  Take a look at domestic ventilation systems that you can invest in. It also helps to keep your windows open every now and then- especially when you’re drying laundry or cooking. Turn ventilation fans on and open vents allow water vapour to escape.

Look for dehumidifiers that you can have at home. A dehumidifier sucks in moisture-laden air and extracts water from it. All the extracted water is stored within the machine and you can just empty it out.

2. Increasing insulation

This can be done by upgrading to double glazing for your windows. Doing this should prevent most of the condensation from collecting as the interior pane of glass will not be in contact with the cold outside environment and so, will not be susceptible to condensate forming. So if you’re still wondering whether double glazing is really worth the cost, this should answer your question. Double glazing goes a long way in protecting your home from structural damage.

To further reinforce the insulation in double glazed windows, we can add thermally broken joinery like Thermal Heart. Here, a nylon barrier is inserted into the frame and it creates an additional insulation barrier, keeping the warm and cold areas separate and reducing heat loss. Using Low E with Argon gas is another option.

 3. Heating and reducing other sources of moisture

home heating

Keeping the heat inside your home above ‘dew temperature’ (i.e. the temperature at which moisture turns into water droplets) helps prevent condensation from forming.

If the natural humidity in your area is already high, then choose your houseplants wisely. It can help to keep away from Bamboo palm, Monstera, Ficus and ginger, as they make humidity problems worse. Opt for Orchids, Spider Plants and Peace Lilies instead.


Is condensation on windows normal?

Condensation on the inside of your window panes is a sign that all may not be right as it is an indicator of excess humidity in your home. The excess humidity could be caused by a faulty ventilation system, poor insulation, or lack of ventilation. Additionally, you should check for a hidden problem like a leaky pipe within your walls or in your basement. Condensation could also indicate that your insulation system has some weak spots that need to be addressed.


Is condensation on windows bad for health?

Condensation on window causing mould

Condensation is an indicator of excess humidity in the environment. If it occurs on the inside of your window panes, it means that all your interiors are exposed to dampness. This leads to the growth of mould or mildew. Have you noticed a musty smell in one or more of your rooms? Spores of mould or mildew can be very bad for health. These can grow on a number of surfaces including carpets, wood, paper or insulation.  It can cause respiratory illnesses and skin irritation to the people living in the building. Early mould exposure has even been linked to asthma in children.


Options for upgrading the insulation of your windows

Changing from single glazing to double glazing will remove most of the condensation on the glass.

Upgrading to Low E with Argon gas will ensure further insulation and make it unlikely to have condensation on the glass in most situations.

If the home owner choses to use standard aluminium with double glazing the glass will have about a 20mm condensation area around the perimeter of the glass, this is because the glass is colder on the edge due to transfer from the aluminium.

When using Thermal Heart TM which is our thermally broken joinery with a warm edge spacer on the double glazing the aluminium is warmer and far less likely to condensate.

Note: It should be mentioned that different cladding systems will determine the success of thermal break joinery. For example cavity systems such as brick will not be as effective as one without a cavity as air can pass around the sides.

For houses that use a sill tray, the bottom of the window and door will not be as insulated as the sides and top. The homeowner can choose to further insulate between the sill tray and the joinery if they chose. The sill tray is only a precaution and not part of the drainage system.

For more information on condensation and thermal break joinery please contact Window Factory.

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