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PVCu or uPVC? Window terms explained

French doors with  white brick courtyard
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French doors with mullions white

Many window suppliers and installers will offer uPVC or PVCu windows and customers can become confused about the difference between the two.

Well, there is absolutely no difference at all except where different window suppliers choose where to put the 'u,' at the beginning or the end.

So what's the difference between uPVC and PVCu, why are there two terms for the same window and why doesn't everyone use one or the other.

What is a uPVC window anyway?

The term is actually an acronym for unplasticised polyvinyl chloride and it's the same type of plastic that is used to sheath electric cable and make inflatable boats and castles.

However, unlike bendy PVC inflatables, uPVC windows are rigid. This is because inflatables made of PVC have had a plasticizing agent added to the mix, while the plastic for windows hasn't -- hence 'unplasticised'.

So the type of uPVC used in windows manufacture is smooth, shiny and waterproof, just like an inflatable, but it is strong and rigid -- an ideal material for constructing a window frame.

There are many other advantages to manufacturing windows from uPVC. The material is extremely long lasting and needs little maintenance while at the same time being eminently recyclable.

Unlike timber window frames, uPVC windows do not need regular repainting, do not rot when they get wet and they are cheaper to produce than aluminium window frames.

Windows, after all, are subject to a lot of abuse. They must withstand a wide range of temperatures, from hot summer days to freezing winter nights as well as wind and rain throughout the year.

Why use the term PVCu at all?

Rigid PVC windows were first made by German manufacturers and quickly caught on when they were introduced to Britain, along with the boom in double glazed windows.

In this country the term uPVC was used to describe this wonder material as the English language usually puts the adjective before the noun, hence unplasticised PVC.

However, in most European languages the adjective follows the noun (e.g., a French house in French is maison francais) and so this type of plastic window was called PVCu.

Britain tended to fall in line with European use when it joined the EU but the original British usage continues.

Technically. the strictly correct term is PVC-u so no one is using it correctly and in fact, PVC-u is not used in the manufacture of windows and doors anyway as stabilisers and additives are always added to the mix to help with colour and to add UV light resistance to stop them yellowing and getting brittle with age.

What's the advantage of PVCu?

We use PVCu in the manufactures of windows, doors, conservatories and sun lounges for a whole variety of reasons.

Modern PVCu comes in a variety of colours and finishes that are highly weathered resistant and low maintenance. PVCu windows do not warp or bend and will not rot, no matter how damp and humid the conditions.

The material is strong and tough, has high impact resistance and insulation properties but can be easily reshaped at high temperatures to make it highly recyclable.