How long do uPVC windows last?

uPVC windows are known for their numerous benefits over wooden and other window types. They’re noise-reducing, more secure, need little maintenance and keep homes warmer, thus saving on energy bills. However, the overall lifespan of uPVC windows will depend on a number of factors.

First of all there’s the quality of the window itself, which we’ll discuss below – something that can vary hugely between manufacturers. Then there are considerations such as the quality of the installation and even the location of the building they’re being installed in.

It’s certainly true that paying more for quality windows and accredited installers up front will save you money and hassle in the long run. Which? cites the average life span as 20 years, whereas it’s been suggested that high quality uPVC windows that are installed correctly can last over 35 years. So exactly how long do uPVC windows last, and how can you ensure that yours stand the test of time?

What are uPVC windows made of?

The essential material in all types of uPVC windows is the polyvinyl chloride polymer. The full name of uPVC is Unplasticised Polyvinyl Chloride, with the unplasticised part meaning it’s not softened to make it flexible.

Each window manufacturer will have a different formula for making their uPVC windows, including ingredients such as fillers and pigments. Other chemicals like metal salts and soaps are used in premium windows for their heat and UV stabilising qualities.

All uPVC windows are not created equally

There are a lot of considerations to take into account when looking at how long uPVC windows last. The quality of the raw materials used makes the difference between a low grade or high quality window. Additionally, the ratio of the chemicals used will affect the window’s ability to, for example, maintain its colour.

Then there’s the fact that the two panes of glass that make up uPVC double glazing are joined at the edge by a polymer compound. By its very nature, this compound will allow small amounts of water to enter the cavity between the windows, hence why a desiccant is also fitted to the windows to act as a drying agent that prevents misting.

A quality polymer compound will prevent too much water from entering the window cavity and ensure the lifespan of the desiccant is extended. If the desiccant becomes too waterlogged it will stop working, and once misting occurs, there is nothing that can be done to resolve it. So, that’s the end of the road for the windows.

The best way of ensuring that uPVC windows are high quality is to look out for these independently verified scores from the British Fenestration Rating Council (BFRC):

  • Windows that keep the heat in (Low U Value)
  • Windows that take the heat from the sun (High G Value)
  • Windows with a A++ WER rating (All of the above in one simple number)

Installation also plays a part, as the window frame needs to allow for ventilation and drainage before the sealed glass unit is added. When setting blocks aren’t used in installation it can put stress on the window each time it’s opened and eventually break the seal. Fitting the windows using putty and oily mastics can also negatively impact the window sealant, causing cracks that will hinder the window’s lifespan.

Signs of poor quality uPVC windows

One of the most obvious cosmetic signs of aging with poor quality windows is the yellowing of white or light-coloured uPVC frames. With low quality windows this can sometimes occur in as little as five years. This issue can be exacerbated by the fact that some parts of the window, such as the sill or upright, are made of a different compound to the rest of the window. Therefore some parts yellow more severely than rest of the windows, making the contrast more stark.

Better quality materials such as pure vinyl virgin resin retain their white colour over a longer period of time. Whereas, when lower quality virgin-only vinyl is used, each time it’s cut and re-melted the vinyl loses its integrity and becomes more prone to UV penetration. Additionally, resins that contain less UV-resistant ingredients, such as titanium dioxide, will yellow more quickly.

Of course some of the more stylish, quality uPVC windows come in a choice of colours, not just white, and allow for a different interior and exterior colour. If you choose these options, you should check that the manufacturer guarantees the colour-fastness of these windows.

Other signs of poor quality uPVC windows are cracks that can appear over time. The cause is low quality resins that expand when they heat up in the sun or when they freeze. However, premium windows will use strengthening ingredients like stabilisers and impact modifiers to prevent this happening.

Moving components such as hinges, locks, springs and internal levers can all wear out over time, so it’s important to choose a company that uses superior fittings and includes these parts in its guarantees.

uPVC vs other materials

There are three main materials used for windows in the UK – uPVC, wood and aluminium. As well as the benefits of uPVC windows listed above, another plus point is that they’re often the most cost-effective to install and maintain.

Aluminium has a similar lifespan to uPVC – sometimes up to around 40 years – however this is offset by the fact it’s usually more expensive. Low-quality aluminium is also prone to rust. While modern timber windows tend to be guaranteed for 30 years, that’s based on the assumption that they are well maintained. They will need to be repainted using quality materials at least every 10 years.

Summary of benefits

The benefits of buying high quality uPVC windows include the promise that they will remain watertight for longer and use ingredients that prevent discolouration and cracking.

When sourcing uPVC windows and installers, choose those with accreditations to neutral industry bodies like the Fenestration Self-Assessment Scheme (FENSA) and the Glass & Glazing Federation (GGF). These kind of guarantees can be transferred when you sell your property up to 20 years after installation, adding value to your home. Companies that provide lifetime guarantees on their windows, fittings and against issues such as discolouration, will assure you of their quality.

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