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.