What material should an external window sill be made of?


The external window sill is undoubtedly a very important element of the finishing of any building, including of course the house. It is worth remembering that windowsills are not only a decorative element of windows and elevation, but they are also supposed to perform practical functions. We are talking above all about preventing the formation of thermal bridges.

External window sills can be made from many types of materials. It is important that the material used is durable and resistant to various weather conditions. This element should also be matched to the window and the style in which our house is built. Although the selection of external window sills may seem to be a seemingly unimportant matter, it is worth paying some attention to this issue, as they are usually installed for many years and it is important that they serve us successfully.

What is the role of external window sills?

The exterior window sill, although often overlooked, has a key function both aesthetically and practically. It is an essential element in creating the appearance of the building, necessary to harmoniously match the colour scheme, type of façade and window joinery.

However, it is worth looking at not only the visual aspect, but also the functional aspect of the window sill. After all, its main task is to effectively protect against rainwater penetrating under the window frame and onto the façade. In this way, the exterior window sill effectively prevents drips and mould growth. Installed at a slight angle, it also allows water to drain freely to the outside. A correctly selected window sill therefore provides an effective protective barrier, shielding our property from unnecessary expenses associated with damage to the window frames and moisture that could compromise the integrity of the building.

What types of external window sills do we have?

We already know what role external window sills play, so it would also be worth finding out what material it should be made of. However, the answer is not clear-cut, especially as there are many solutions available on the market. Importantly, there is no single, ideal solution for everyone, as we should take into account, for example, individual preferences in terms of aesthetics or, of course, our financial capabilities.

Therefore, the following types of window sills that we will present to you differ in terms of durability, resistance to damage, colour, maintenance and, consequently, price.

Steel window sills

Galvanised steel window sills, also known as the economy option, are very popular mainly due to their attractive price. The main advantage of steel window sills is their availability in various sizes, which makes it easy to find the right product even for non-standard window dimensions.

Their low weight also means that there are virtually no restrictions on their use, even when replacing window sills in older buildings. The process of galvanising the steel and coating the surface with various types of varnish considerably extends their durability, and regular maintenance guarantees long-lasting use for many years.

An additional advantage of steel window sills is the wide range of colours available, which makes it easy to harmoniously integrate such a solution into the overall shape of the building. Nevertheless, it is worth mentioning some disadvantages, in particular the noise created when raindrops hit the surface of the sheet metal, which can be a nuisance for some property owners.

Plastic window sills (PVC)

Plastic window sills, often referred to as PVC window sills, are made of foamed or hard PVC, which is then covered with a laminate, i.e. a material used for the production of the most popular window profiles. The advantage of this type of window sill is, above all, excellent damping of falling raindrops, which we could not say about the previous solution.

Plastic window sills can also be chosen from a wide range of colours, as the colour possibilities of veneers are practically endless. As a result, we can find, for example, sills imitating wood, which perfectly match the façade and especially the window frames. Such window sills are also resistant to corrosion and acid rain. They are easy to keep clean, but unfortunately they are not very durable, so this may not be the best solution for those who intend to install window sills for a long time.

Aluminium window sills

Aluminium window sills, although similar in some aspects to the steel window sills described at the beginning, are distinguished by better technical parameters. This is because they are characterised by greater rigidity and resistance to corrosion than their predecessors. In addition, the protection of the surface with varnish means that they do not require regular maintenance. Their advantage also lies in their higher resistance to moisture, UV radiation and mechanical damage. They are also sold with matching accessories. A wide range of colours, allowing powder coating in a RAL colour of your choice and the option of a smooth or embossed surface, are additional advantages.

Unfortunately, the disadvantage of this solution is the expansion of the material under the influence of heat. It is therefore advisable to maintain an expansion gap at the ends of the sills and around the fixing screws. There is also the risk that the noise of falling raindrops hitting the aluminium surface can be annoying. It is therefore worth taking this into account when choosing aluminium window sills. Finally, it is also worth mentioning the price, which will be slightly higher than for steel window sills.

Ceramic window sills

Ceramic window sills and clinker sills are an option that is very visually appealing. It is therefore very often chosen by lovers of original design who are looking for an unconventional finish.

This type of parapet is usually made from bricks, fittings and clinker tiles. Consequently, they are durable, frost resistant, as well as characterised by low water absorption and ease of installation. The main disadvantages, on the other hand, are considered to be their poor resistance to mechanical damage, which is why we do not recommend using them on the ground floor or with windows that reach to the floor. The impact of a hard object may result in chipping of a brick or tile fragment.

It is also worth mentioning that ceramic window sills are quite expensive and heavy, so in the case of old buildings it may be a problem to install them. However, many, as we have already mentioned, are persuaded by their exceptional aesthetics, which is why they are very much chosen for rustic-style buildings.

Granite window sills

Exterior window sills made of granite represent exceptional durability. Granite, being a natural stone, ultimately enjoys widespread use due to its robustness. It is a popular choice for those who are planning an investment for years to come, both in terms of the finishing elements of the house and the garden. Granite shows resistance to dirt and adverse weather conditions, and is not easily damaged due to its hardness.

It is also characteristic of granite that it ages with dignity. Its durability is not affected by time. In addition, granite looks exceptionally aesthetically pleasing, characterised by its elegant appearance and fascinating texture. By installing it under the windows, we can be sure that it will serve us for many years. It comes in a variety of colours, from white to black, with earthy tones, as well as colours such as pink, green and red. Although it is most commonly found in shades of grey, the variety makes it possible to match different styles and aesthetic preferences.

Conglomerate window sills

If you want to spend a little less, it is worth considering conglomerate window sills, which look very similar to the granite described above. This is all because conglomerate contains granite or marble, which is processed with the addition of polyester resin.

Consequently, this material is considerably cheaper than stones without any admixtures. In addition, due to the pigments added to its formation, the choice of colours is enormous. Conglomerate is also very easy to care for and has a high durability.

Wooden sills

Last but not least, we could not fail to mention the classic and timeless wooden window sills, which are extremely popular among people who appreciate the natural beauty of this noble material. Undoubtedly, the greatest advantage of this material is its aesthetics and ease of adaptation to buildings with a variety of architecture – from rustic, through classic to modern. Wooden window sills also harmoniously harmonise with wooden windows, providing a stylish complement to the overall composition.

Nevertheless, there is a disadvantage associated with wood as an outdoor material, namely the need for regular and labour-intensive maintenance. If care is neglected, the result may be that the wooden window sill, instead of being decorative, will quickly start to undergo unsightly changes. The process of greying and cracking of the surface will be a clear sign that the wood has not been properly protected. Factors such as water, snow, frost or fungi have a huge impact on the natural degradation of the raw material, which underlines the need for systematic application of wood protection products.

So, as we can see, when choosing a material for use in external window sills, we cannot limit ourselves to aesthetics alone. Price, durability of the material or the need for maintenance are also important. It is also worth noting whether the chosen sill has a special vertical strip with a special grooved undercut, which allows water to flow freely in front of the face of the building instead of along the façade.

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