Window in an empty room

PVCu or uPVC – What’s the Difference?

If you’ve been shopping for exterior doors or windows recently, you might have come across two similar terms: PVCu and uPVC, and wondered what the difference is between them.

Let’s cut to the chase: there is none. Any time you see the term ‘uPVC’, you can mentally substitute the term ‘PVCu’ (and vice-versa). So, why are there two terms for the same thing?

Let’s take a look.

So what is uPVC (or PVCu)?

Let’s rattle through a quick uPVC definition. The acronym stands for unplasticised Poly Vinyl Chloride. It’s the same stuff used to make faux-leather clothing, inflatables, and electric cable insulation, except that it’s not had a plasticising agent added to it. This agent is what makes the material flexible. Without it, uPVC is tough and rigid, and at the same time waterproof and glossy. It’s the perfect material, in other words, from which to build a window frame.

What uPVC means in practice is chunky white window frames. The material is recyclable, and cheaper to manufacture than aluminium. When uPVC was first introduced in the 1980s, it had another advantage over aluminium – it didn’t conduct heat as easily (aluminium windows have since been designed with effective thermal breaks in the centre, meaning this isn’t such a problem).

uPVC enjoys a considerable advantage over timber in that it doesn’t need to be finished and maintained in the same way – the topmost layer is inherently glossy, which means that stains and moisture will slip from the surface. As such, you needn’t worry about choosing paints or adding additional hardware.

It’s for these reasons that uPVC is to be found on so many British homes.

Why Do We Use the Term PVCu?

uPVC first entered Britain thanks to German manufacturers, and, as a result of the double-glazing boom of the era, it ended up becoming something of a marketing buzzword. Everyone, it seemed, wanted their house equipped with energy-efficient uPVC windows.

So, if uPVC was a perfectly good term, why did ‘PVCu’ come about? The answer comes from mainland Europe, where sentences are often formed with the adjective after the noun (just think of Fédération Internationale de Football Association). In the 1980s, it was decided that British manufacturers should use the same term as their European counterparts in order to avoid confusion. And yet, making this transition proved rather difficult – as getting an entire industry to change its habits often is. We’re thus still using the same term decades later, and there’s no indication of this changing anytime soon!

As a side benefit, ‘PVCu’ might appeal to those of us who appreciate consistent capitalisation. ‘uPVC’ at the start of a sentence just doesn’t look quite right.

What’s the Correct Term – uPVC or PVCu?

Some may insist that one term or the other is correct, but there is no practical difference between the two. Whichever you prefer to use, you’ll be understood by our team – and the benefits of the material remain the same!

Looking to replace your windows? Start your shop for our full range here.

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How to Whiten Yellowed uPVC Windows

Arguably the most popular material for modern windows is unplasticised Poly-Vinyl-Chloride, or uPVC. It’s robust, inexpensive, and lasts for years with minimal maintenance. To keep yours looking spotless, you only need give it the occasional wipe down with a damp cloth.

Over time, however, certain sorts of uPVC are prone to discolouration. Those brilliant white frames, if exposed to the elements for long enough, will turn an unsightly shade of yellow. In this article, we’ll take a look at the problem, why it happens, and see whether there’s anything to be done once your uPVC has gone yellow.

What Causes uPVC to Turn Yellow?

There are several things which can cause uPVC to turn yellow, but the likeliest culprit is exposure to UV light. You might notice that your windows aren’t so yellow in places where the sunlight is restricted (your south-facing windows, for example, might be most affected).

One of the major advantages of uPVC is that it’s recyclable, and therefore environmentally friendly. But it’s for this reason that not all uPVC windows are created equally. If your window has been made using extra plasticizing agents and pigments, then it might be more vulnerable to discolouration.

How Not to Whiten Yellowed uPVC Windows

Having identified the problem, we’re left with the question of how to make yellow uPVC white again. You might be tempted by several common cleaners, some of which are to be avoided at all costs. Two offenders in particular stand out:

Bleach might seem a sensible option for cleaning yellowed uPVC. It turns things white, doesn’t it? Why shouldn’t it do the same to your window frames?

Unfortunately, it’s not that simple; bleach will react with the PVC and turn it a disastrous shade of brown. If you use it, even in diluted form, you can expect a total catastrophe that can only be fixed by replacing the entire window.

Sandpaper might also seem a sensible option. If the top layer is discoloured, then surely all we need to do is scrape it away to reveal the whiteness beneath. Again, this is a misunderstanding of how uPVC works – the topmost, glossy surface is created as the plastic is manufactured – the interior of the material is quite different. It’s dull, and won’t repel water or stains in the same way. If you sand your uPVC window, you will ruin it.

How Do You Clean Yellow uPVC Windows?

Depending on the nature of the staining, you might have some luck with more gentle cleaning solutions. Baby wipes have been known to lift away some stains, and make a good first point of call if you have access to them. Household cleaners like CiF should be regarded with some caution; be sure to check the bottle doesn’t contain any bleach.

You can also find some specially-formulated uPVC window cleaner on the market, which may restore new life to ailing windows. Even if you don’t experience stellar results, you can at least be sure that you aren’t going to do any harm!

Looking to replace your windows? Start your shop for our full range here.

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uPVC kitchen windows

A Guide to uPVC Windows

In the UK, the majority of window frames are manufactured using uPVC. uPVC windows offer several distinct advantages over windows made from aluminium or timber, the most obvious of which is their affordability.

In this article, we’re going to take a closer look at uPVC windows, and what they can and can’t do. We’ll do this by addressing a few questions about the limitations of uPVC, and discussing which ones can and can’t be overcome.

What is uPVC?

First, let’s establish exactly what we’re talking about. PVC, or poly-vinyl-chloride, is a form of plastic perhaps best known as a substitute for leather. You might have seen tarpaulins, dresses and coats made from the stuff. In this context, the material has been supplemented by a plasticising agent, which is what allows it to become flexible and stretchy.

That’s not the extent of PVC’s powers, however; if an extra ingredient is added, the material sets in a rigid, tough form. This material is known as unplasticised PVC. It’s particularly suited to use as a building material, and it’s the stuff from which most windows in the UK are now built.

Can uPVC Windows be Painted?

The overwhelming majority of uPVC windows are brilliant white, and those that do come in other colours are given their pigment at factory level, before the plastic has set. uPVC is naturally resistant to paint. Their surface is low-friction, which allows them to resist stains, and rainwater to quickly slide away. For the most part, this is an advantage, as it makes cleaning the windows easy, and it gives the surface of the material a durable, glossy appearance. It also makes painting your uPVC window very difficult.

This doesn’t, however, mean that painting a uPVC window is impossible – It just means that any coat of paint you apply will be more prone to peeling and warping over time, as differences in pressure and temperature gradually lift the paint from the surface of the plastic.

For best results, we’d suggest masking the glass thoroughly and applying a spray-on coat of matte paint. If you want a gloss finish of the sort you’d get on a door, then you’ll need access to a heavy-duty paint-sprayer. If you’re going with a gloss paint and a brush, then you should be prepared to apply multiple coats, and sand-down with extremely-fine sandpaper. Be very careful that you don’t sand all the way down into the plastic; once the top layer has been scraped off, you’ll never get it back.

While painting can be a great way to lend a new lease of life to aging uPVC windows, if you’re investing in new windows and aren’t keen on them being white, we’d strongly suggest opting for engineered timber or aluminium windows instead. The material simply isn’t built to be modified in this way, and looks and functions best when left in its usual glossy-white state.

Can uPVC Windows be Recycled?

One of the reasons that uPVC is so affordable is that it can be easily reshaped and recycled. It’s a thermoplastic polymer, which means it’ll melt when exposed to a sufficiently high heat. uPVC windows should therefore be taken to a recycling facility when they reach the end of their lifespan. Find your local recycling centre, and remove any non-uPVC materials, like seals, and metal hinges, from the window.

How Long Do uPVC Windows Last?

uPVC windows can easily last three decades or more. To be assured of the best possible quality, we’d strongly recommend checking the length of the warranty before deciding. If the supplier isn’t prepared to put their money where their mouth is when it comes to longevity, it’s time to start worrying. Look for a warranty of ten years.

Of course, this is assuming that your installation was carried out by an expert under good conditions. If the window is misaligned or otherwise poorly-installed, you can expect it to fail much sooner.

When failures do occur, it’s usually a part of the window that’s not made from uPVC that’s to blame. For example, moving parts like seals and hinges might wear out and become misaligned thanks to frequent stress and gravity. These hardware components can in most cases be replaced while leaving the window itself intact.

Finally, there’s another factor complicating things here, and that’s the improvement of the technology over time. Given that modern windows are far more efficient than those manufactured even just ten years ago, you might consider it worth your while to swap out for some new ones.

Signs of an aging window

If you think your uPVC windows are looking a little sorry for themselves, then you’ll want to keep an eye out for the following.

Condensation occurs between the panes of a double-glazed window when the seal around the edges has broken, and water vapour has been allowed to creep in. The presence of such a gap means that all of the inert gas inside the panel has escaped, which will hugely reduce the efficiency of the window.

Draughts around the window frame can be fixed without replacing the window, but they’re usually evidence that the window is on its last legs. If you find yourself shivering every time winter rolls around, investing in replacement windows might make financial sense.

Discolouration. uPVC windows are white when they’re first installed, but this can change. Prolonged exposure to ultraviolet light can, over time, cause that white to turn yellow, which, amongst other things, will devalue your property. If your home is equipped with old, yellow windows, then a replacement set is probably long overdue.

Can You Drill into uPVC Windows?

Unlike timber, uPVC is not designed to be modified once set. While it’s possible to do so, there are better alternatives. For example, if you need to drill a hole to pass a cable from the outside of the property, it’s almost always better to drill said hole in the surrounding wall than it is through the window frame itself. The same applies if you’re fitting blinds or curtains to your uPVC windows.

uPVC windows are very rarely uPVC all the way through – they often contain metal cores which can make drilling problematic.

What’s more, sealing the edges of the hole once you’re done will be difficult. You’re more likely to compromise the performance of the window than you are to improve it. A gaping hole in your window frame will look amateurish, particularly when you come to sell the house.

But what if you’re looking to replace your uPVC handles? Won’t that require drilling into the window? No, because uPVC handles are not interchangeable, like their counterparts on timber windows. They’re designed to remain in place for the lifespan of the window.

How Can You Maintain uPVC Windows?

To ensure that your windows enjoy the longest possible lifespan, we’d suggest giving them some occasional TLC. We’ve covered how to clean and refresh them in previous blogs, so be sure to give them your attention.

What’s Wrong With uPVC?

As we’ve mentioned, uPVC compares favourably to timber in terms of how much maintenance it requires, but it’s not a perfect material. Amongst its disadvantages is a tendency to expand during periods of hot weather. In extreme cases, this can exacerbate any existing misalignment issues and make it difficult to shut the window. There are a few things you might do to combat this problem, and we’ve covered a few of them here.

Homes in conservation areas are subject to stricter planning controls, which might make installing uPVC windows impossible. For all of their many virtues, uPVC windows will reliably undermine the impression that you’re walking through a 16th-century countryside village. As such, check with your local authority before you place the order – as having to remove your windows a few days after installing them can be embarrassing, not to mention costly.

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Window in an empty room

Why uPVC Expands (and what to do about it)

uPVC is a commonly used building material for many modern homes but there are few people who actually know what uPVC is and why it’s chosen. uPVC is the abbreviated term for unplasticised polyvinyl chloride. Polyvinyl chloride is a lightweight and sturdy plastic that is normally made into a flexible material by combining it with other plasticisers. uPVC however is the original unaltered version of polyvinyl chloride. It remains strong and rigid, making it a perfect choice for construction purposes.

uPVC is often used for windows, doors and guttering; external components that are generally exposed to the elements. While uPVC is a sturdy material that will withstand wind and rain, like all plastics it can suffer in the heat. uPVC expands in heat and while it shouldn’t cause too many issues, it can be far from ideal for homeowners.

So how can you prevent uPVC windows and doors from expanding in the heat?

If the uPVC has expanded in the heat, you may have issues shutting or locking your windows and doors. When the temperature cools the uPVC will return to its original form, however this is not helpful if it’s a warm summer night and you need to secure your property before going to bed. Unfortunately, there’s not a lot you can do but wait for the plastic to cool. You could give it a helping hand by pouring cold water on to the frame but if it’s a particularly hot day this won’t make much difference.

If you really need to shut or lock your door and can’t afford to wait for it to cool, you could try and adjust your hinges. uPVC doors have easy to alter flag hinges to specifically accommodate for heat expansion so you could adjust them as required. Adjusting the hinges however may be problematic because while it solves the issue in the short term, when the uPVC returns to its original form you may struggle again to close your door and it may need adjusting back.

If the problem keeps recurring you may need to alter the size of your door or have them replaced. When the uPVC expands, make a note of the issue. For example is your door catching on the bottom of the frame? If so you could consider shaving some length off the bottom of your door. This is a risky manoeuvre if you don’t know what you’re doing however so may be worth seeking professional advice first.

Should you avoid uPVC windows and doors?

uPVC windows and doors do have many benefits. As a material, uPVC is easy to clean, robust in design, withstands cold and wet weather, and is often more affordable than wood or aluminium.

Unfortunately uPVC doesn’t have the longevity that other building materials do. Time can take its toll on uPVC windows and doors, making them discolour and break down. Unlike other materials, uPVC doors are also difficult to fix so if breakages do occur they may need replacing.

uPVC doors also have the issue of heat expansion which can be troublesome, especially if you have to keep adjusting the hinges. This tends to be more of an issue for darker uPVC or woodgrain models, but is also commonly the case for white uPVC.

The type of material you choose for your windows and doors comes down to personal preference. Sure, uPVC is cheaper and easier to maintain and for the most is a sturdy material, but it may not be the best choice for you.

Heat expansion is a worry as is the possibility of having to replace your windows and doors sooner than you’d prefer. Wood is a good alternative. It’s energy efficient, incredibly durable if cared for properly, and can be customised with paints or oils. However wooden doors do require more maintenance. What you choose then will depend on personal preference. It’s not that uPVC is a bad building material – there is a reason it remains a popular choice – there are simply things to consider when deciding whether this material is right for you.

Looking for new windows for your home? Browse our sliding sash or casement windows or find out about our handmade bespoke windows.

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