Condensation on Double Glazing

what is condensation?

Condensation is the process where water vapor becomes liquid. It is the reverse of evaporation, where liquid water becomes a vapor.

Condensation happens one of two ways: Either the air is cooled to its dew point or it becomes so saturated with water vapor that it cannot hold any more water.

Condensation itself is not thought to be dangerous however if it is not maintained efficiently
then it can develop into mould which is linked to health conditions such as asthma and Bronchitis.

Rain drops on the window
glass desgin

The Different Types of Condensation

Surface condensation

This is the most familiar type of condensation, taking the form of water on window panes.

Cold-bridge condensation

This occurs when warm, moisture-heavy air comes into contact with surfaces at or below its dew point. This occurs at the base of external walls.

Warm-front condensation

This occurs when warm, damp air gets into a cold house.

Surface condensation

This happens when warm, moist air diffuses into a vapour-permeable material, such as fibrous insulation.

Reverse condensation

TThis is also called “Summer condensation”. If rains drenches a wall and strong sunlight then dries it, the heat can actually force water vapour into the wall.

Radiation condensation

This is sometimes called “clear night condensation“. If there is a sudden temperature drop at night, it can cause condensation on the underside of roof coverings.

If your home is suffering from condensation you will start to see signs of it very quickly which include

Streaming windows

Wet walls

Damp areas on walls

Wallpaper peeling

Signs of mould growth

Musty smell on clothes

Condensation inside glass of your windows

If you’re finding the inside glass is gathering condensation and making your window glass wet but it doesn’t necessarily mean there is a fault with windows.


The main reason this type of condensation gathers is due to factors inside, such as the ventilation and how many people live in the property. Things such as purchasing a dehumidifier can help massively and mean that you dont need to replace your windows.

Condensation on the outside facing glass of your windows

Condensation forming on the outside glass is really good sign that your windows are working and keeping your home well insulated.


Such condensation should disappear once the temperature outside heats up but this does not indicate any fault with your windows or need replacing

Condensation between the two panes of glass

Double-glazed windows are designed with two panes of glass, separated by a small gap of air,making it harder for heat and noise to pass through.


If you’ve had double-glazed windows for a few years, you may have noticed small droplets of water inside gap. These droplets can sit at the bottom of the unit, or trickle down from higher up.


Even the tiniest gap or break in this seal allows moisture from the air to get in, leaving the inside of your double-glazed windows wet.

Why are double glazed windows getting condensation ?

Once the seal has been broken and moisture has got in, the vast majority of that moisture will become trapped inside the double-glazed unit.


When the droplets are heated up, because the sun is shining on your windows, for example, the moisture will be vapourised back into a gas.


Eventually, it will be drawn back out onto the cold surface inside your double glazing, becoming condensation.

Condensation is arguably more of an eyesore than water droplets, as it can mist up your double-glazed windows from the inside.

Reducing condensation inside your double glazing


Keeping your home well ventilated is one free and easy way to lower the humidity and reduce condensation inside your windows.

Try to regularly open windows to allow air to move freely and let moist air escape from the property. its best to keep windows open when doing activities such as bathing, showering and cooking

Reduce the moisture

Everyday home activities produce moisture into the air that cannot be avoided.

Little changes such as having your tumble dryer vented outside and hanging washing
on an outside line instead of drying it inside the home can really help.

If you have a condensation dampness issue it is never a good idea to dry clothes indoors or over radiators.


Window replacement is the most obvious way to eliminate condensation. A new unit will have new seals which will stop moisture getting in.

It can be pretty expensive replacing all of your windows. Replacing double-glazed windows also means getting rid of your original windows, which may be detrimental to the overall look of your property.


Double-glazed windows can be repaired to reduce the effects of condensation inside the unit.

Secondary glazing

Arguably the best solution for reducing condensation on double-glazed windows is secondary glazing. It works by installing a secondary window on the inside of your existing fixtures.

There’s no need to get your existing windows replaced and impact the style of your home or commercial building. Even better, secondary glazing provides a long list of other benefits.

As well as reducing condensation, it will improve thermal efficiency, reduce noise levels and bolster your windows’ security.

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The cost of energy bills increases every year, but without having to turn up the heating, double glazing works to keep your home warm.
On the basis of how energy-efficient they are, Windows has various types. The best-performing ranking is an A+, and G is the lowest.
Because of advanced glass technology, many new windows are double glazed with improved energy efficiency. An outer bane allows for heat to pass through.

The coated glass is able to select the wavelengths of energy allowed to pass and which wavelengths to reflect. More heat is kept by the inner panel,
reducing the need to use central heating Double glazing also creates insulation barriers by trapping air between the glass panes.
Argon gas is used to provide effective insulation, and the window is fitted and sealed to ensure there is an airtight fit

Replacement windows will help you save money you your energy bills; however, for a bigger impact, consider making additional changes to your home:

Install a programmable thermostat
Purchase Energy Star certified products, including appliances and electronics
Turn off electronics, appliances, and lights when not in use
Keep your home well insulated, particularly if you live in a colder climate like Boston
Weatherize your home before the change of each season
Avoid using your appliances in peak times, particularly in the summer
Keep your thermostat lower in the cooler months and warmer in the hotter months
Simple changes could help you save big on your energy bills.

Both internal and external sliding and folding doors are a perfect space-saving addition to your home. They can open up to create wide open plan areas inside, while by opening to the outside, they provide a seamless transition to the garden.

We know that if your doors and windows do not provide quality thermal performance, they could burn a hole in your pocket in the form of electricity bills. The advantage of Aluminium Windows and Doors is also that it is a conscious choice. They are energy efficient, eco friendly and highly recyclable especially when the performing glass is chosen wisely.

At Deltra Global, our TOSTEM windows have a single laminated solar glass which not just reduces noise and heat gain but also makes the windows highly energy efficient.

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