Windows provide any home with a clear view of the outside as well as reliable protection against burglary and inclement weather. However, installing a uPVC window sill is an absolute must if you want to fully utilise the potential of your windows. This construction element provides house plants or other decorations a convenient place on the inside, while the external uPVC window sill protects the masonry from accumulating moisture and grime and modern thermal insulation techniques also reliably prevent harmful heat bridges from forming.

The Advantages of the Material

Unplasticised polyvinyl chloride is a synthetic building material used in various fenestration applications, ranging from doors and window frames to a variety of exterior trims and cladding elements. This modern material is in high demand because of its advantageous natural properties, such as:

Cost-efficiency
Great thermal insulation
Durability and longevity
Low maintenance requirements

One particular benefit of choosing an unplasticised PVC window sill is the simple fact that the one main disadvantage of the material - higher flexibility resulting in lower burglary protection when compared to materials such as wood or aluminium - is entirely irrelevant for the purpose which a window board has to serve.

When installing uPVC windows, their low prices are typically seen as a compensation for the security drawbacks of the material. But as far as window boards are concerned, the great affordability of the synthetic material offers a significant benefit - with no associated drawbacks.

Avoiding Thermal Bridges

Unplasticised PVC is a great thermal insulator, particularly when shaped into multi-chamber profile systems. Usually uPVC window sill models employ this structure as well, in order to minimise the amount of heat applied directly to the adjacent frame. This means that high-quality synthetic window boards do not negatively impact the U-value of the actual windows - as long as they are installed correctly.

Low Maintenance and easy Cleaning

In contrast to timber and aluminium, uPVC can neither rot nor rust when coming in contact with moisture. This has made both external and internal uPVC window sill profiles very popular, as they not only reliably protect the masonry from rain water and dirt, but also provide these benefits over a significant amount of time. In contrast, any damage to the surfaces of an anodised aluminium sill or wooden models can open them up to harmful moisture.

Interior or exterior - which Window Sill benefits most from uPVC?

As a sill is typically constructed and installed differently depending on whether it is meant to be an interior or an exterior model, uPVC sills can have different benefits depending on their position.

When installed on the inside, uPVC sills benefit from the significant advantage of being the most inexpensive option. However, their robustness and longevity do not provide as much of a benefit as these properties would offer on the outside of your windows.

Sometimes derided as the 'plastic window sill' option, unplasticised polyvinyl chloride sills are a much smarter choice than reputation would have you believe. Simply adding wood-grain decors and the right RAL colour allows you to benefit from the properties of the synthetic material and the aesthetics of a wooden sill at the same time.

The uPVC sill really shines when installed outside; though aluminium is arguably more robust and thus provides better resistance against inclement weather, uPVC is fully sufficient for exterior installation. This is because, in contrast to the actual frames of windows, the sills have little to no effect on burglary protection, thus depriving aluminium of its great benefit compared to PVC.

Fitting uPVC Window Sills

Since unplasticised PVC is a highly insulating material, even laypersons can install them without the need for professional help and without special tools or accessories. However, a few points should always be kept in mind. Perhaps most importantly, even highly insulating PVC should be mounted in such a way as to not negatively influence the thermal insulation properties of the windows themselves; as insignificant as this influence may be. For this reason, it is strongly recommended to use connecting profiles to thermally insulate the windows from the sill.

Further, it should be kept in mind that an exterior window sill is affected by the weather and can expand or contract with temperature changes. While this effect is particularly pronounced with models made of metal, large-sized uPVC sills should nonetheless feature a joint filled with a number of elastic materials such as silicone to prevent damage that may occur as a result of warped sills.

Customising your Window Sill

Just like wooden and aluminium models, uPVC boards can be painted in any of the numerous colours of the vast RAL colour scale. Since uPVC can experience changes in colour when exposed to UV radiation for a long time, it is of great importance to choose a RAL paint for your window sill that features high lightfastness.

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