How long does double glazing last?

How long should double glazing last?

Trying to answer the question of how long should double glazing last is like trying to answer how long does a car last, a carpet or even a shoe. The reality is – it depends.

Two people can paint their house with the same quality exterior paint but they won't get the same results. The person that lives in an exposed location next to the coast will need to repaint their house far quicker than someone who lives in a sheltered location. A wall facing south that gets a lot of direct sunlight will peel and crack far quicker than a sheltered wall facing east that doesn't get any extremes of temperature or weather.

A house painted badly without preparation will not last as long as a house that has a quality finish by a reputable tradesman.

In the same way, the lifespan of your windows and how long double glazing should last is dependent on the environment, the quality of the windows and the quality of the installation.

Windows can last anything between 10 - 50 years depending on how well they are made, installed and looked after.

On average, double glazing windows should last 20 years minimum.

How long does double glazing last?

In reality, how long 'does' doubling glazing really last?

The good news is that over the last fifty years, technology for manufacturing and materials has advanced so much that updated and better products are being developed all the time. Homes built today are far superior to those built post-war.

Double glazed windows today have a vastly improved thermal performance to windows made in the eighties, nineties and noughts.

A double glazed window produced today will have a lifetime of 25-30 years and more if fitted in a sheltered location and not subject to any extreme weather.

A double glazed window that does face exposed weather will expect a lifespan of 20 years.

How long should double glazed sealed units last?

The integrity of a double glazed window is dependent on the quality and production of the double glazed sealed unit.

The material and quality of the frame are still important, but if your sealed unit fails then you lose all your double glazing insulation properties for the window.

Most manufacturers guarantee and offer a warranty for the double glazed unit. At Everest, we offer a lifetime guarantee against fog and condensation inside our units used in our windows.

We consider a minimum of 20 years' lifespan from our double glazed sealed units, but 30 years' lifespan and more is what we expect (when fitted in a sheltered location).

How long do windows last?

As mentioned above, some factors can halve or double the lifespan of your double glazing and windows. The predominant factor being temperature.

A window is designed to take a lashing from rain, but window frame materials find it challenging to cope with extremes of temperature as these make them expand and contract.

If you think of hard rocks by the coast – rain and water lashing at them every day for years doesn't wash them away. They might erode over time but are mostly resistant to the waves (unless they are a significantly soft limestone or chalk rock). The Achilles heel of rock is heat and cold – constant contraction and expansion over time form small fissure cracks in the rock. If water gets into the crack and freezes it expands – widening the crack. Over the years of this freezing cycle eventually, the rock cracks open and split apart.

The insulating Argon gas between the panes of glass in the double glazed sealed unit reacts to changes in temperatures by expanding and contracting. This action is called thermal pumping and windows that face south in direct sunlight are the most susceptible.

Thermal pumping puts stress on the seals of the double glazed unit as it constantly expands and contracts. Like the rock, the seals start to show small fractures that grow in size over time and airflow is sucked in and pushed out through the cracks as the gas expands and contracts.

This is when a double glazed unit is compromised and fails.

What factors affect the lifespan of double glazed windows?

Location

Sheltered or exposed positions will make the biggest difference in how long your windows last. A window on a coastal property will have a significantly shorter lifespan due to acidic saltwater than a window in the countryside.

Quality of manufacture

There's a reason that we have antique furniture. It's because cheap Swedish furniture didn't exist 100 years ago! Windows made from reputable manufacturers and craftsmen will long outlive anything cheaply made.

Quality of installation

Your quality window is dependent on being fitted correctly by a skilled fitter. It will only last if it sits correctly in the opening, without gaps and all fully sealed. Badly fitting windows will allow water to seep between the brick and the frame causing endless damp problems and can rot a timber frame underneath.

How do I know if my double glazing needs replacing?

Energy-efficient windows are one of the structural parts of a property that significantly contribute to reducing energy bills and keeping your home warm.

To ensure you're not paying more than you should for your heating bills, it's important that your windows continue to perform as they should.

If you've noticed that your heating bills are creeping up it could be your double glazing that is starting to fail.

You'll know your double glazing needs replacing if it does any of the following:

You can feel draughts around the frame

Run your hand around the frame, does it feel draughty and cold? Either the seals around the frame or the seals in the double glazed unit could've failed. If the unit fails, the Argon gas that insulates the panes of glass dissipates and this will result in decreased U values.

There's condensation in-between the panes, inside the double glazed unit

Desiccant (usually silica gel) is used inside the spacer bar of the sealed unit to absorb the natural moisture that occurs between the panes keeping the unit fog-free. If the seals of the unit begin to fail, more moisture is drawn into the unit by thermal pumping and saturates the silica gel.

This is when fog and condensation begin to form in-between the panes of glass as the first sign that your sealed unit has failed.

Note that condensation only forms on glass in direct sunlight, so a north-facing window might have failed seals but won't show condensation. Sometimes you can only tell a seal has failed by inspection or testing with a thermal camera.

Also, note that not all windows fail because of thermal pumping. Seals defectively fitted in the manufacturing process and bad batches of windows can produce failed units. For this reason, it's essential to only buy double glazing from reputable suppliers who guarantee their units.

There's white dust inside the double glazed unit between the panes

Once the desiccant becomes saturated, it starts to degrade and particles begin to drift around the sealed unit. White snowflakes of dust settle on the inside of the panes of glass. This is a sure sign that your double glazed unit is compromised and has failed.

You can hear a lot of noise from outside

Double glazing acts as an insulation against temperature and sound. When your windows are closed, the outside noise should be reduced and muffled. If you are noticing more noise, the Argon gas could’ve escaped from the sealed unit reducing your insulation.

The windows won't open or close properly

If the window isn't closing flush, this would mean the seals are not contacting and the insulation of the frame is compromised. This can be caused by cheap uPVC. If you have tried to adjust the hinges of the window then the frame may be at the end of its life.

The frames are visibly degraded – yellowing uPVC or cracked timber

The double glazed sealed unit might be an integral part of the window but the frame is also an essential part that supports the unit. Wooden frames that are rotten and cracked can’t be salvaged and uPVC that is yellowing or warped cannot be saved.

Remember to always check the manufacturers' guarantee – if they have failed within warranty you can get them repaired or replaced.

How long does double glazing last:

If your windows are showing any of the signs that they need replacing, our expert team can help you to choose the best solution for your home.