What are Tilt and Turn Windows?
Like so many things in Germany that work properly, tilt and turn windows are made differently. Why is this? First off, it is partly because German energy conservation laws have a higher standard than in the UK. Secondly, however, it is also due to the fact that the German consumer tends to look towards the long term. They are looking for a product that will last a long time, not just five or 10 years.
By law, a product used in a home in Germany must be fit for purpose for a long time. This is unlike the UK, where ‘fit for purpose’ usually means that it is operational when new and for only a short period (usually a year) after. Many manufacturers have bold claims such as 50-year guarantees. But, when you read the small print, you discover that these are very much conditional and often mean little in practical terms.
Tilt and turn windows are the norm in Germany and many other northern European countries, where the winter weather is much colder than in the UK.
How do they work?
A tilt and turn window opens on two axes: tilting when ventilation is needed, and turning mainly to provide a means of escape from a room in case of a fire. This is unusual compared to the mechanisms found more commonly in UK windows.
In the ’tilt’ position, the window tilts inwards into the room, remaining fixed at the base. This allows ventilation, whilst still maintaining a high level of security and shielding off the rain. Our heavy-duty window opening mechanisms provide security even when open.
The tilt and turn mechanism
The tilt and turn mechanism allows for the insertion of three butyl rubber seals in the window between the frame and the opening sash, made up of an external seal, mid-window seal and inner seal.
Many non-tilt and turn manufacturers are limited to one or two seals due to the constructional make-up of the frames and the reluctance to bear the additional machining costs of making this feature. Essentially, the cold air is kept at the outside of the window frame and cannot reach the inner edge.
Safety first! As the windows tilt inward, they can be used to ventilate a space in bad weather and be opened with lesser risk of a break-in. The tilt function usually opens by just 5-10cmm, meaning that there is not enough room for someone to climb or reach through.
The turn function is operated by putting the window handle in the second of its two positions. This also allows the window to be cleaned from the inside of the building.
Could tilt and turn windows benefit you?
Fundamentally, tilt-turn windows and doors offer:
- Better airtightness, due to both the locking points and the rubber seal which runs around the whole perimeter of the window, thus pulling the window sash tightly into the window frame.
- Lower thermal gradient in the window frame. A tilt and turn window can have up to four airtight seals across the frame. Most normal UK windows have just one. Don’t be confused by flap seals around the external perimeter of the outer frame, which have cut-outs for drainage. This is just a weather seal that allows cold air to enter into the gap between the opening sash and the window.
As a result, the distance between the outside air at zero degrees and the inside air at 20 degrees is only the width of the airtight seal. As most tilt and turn windows have 2-3 seals, the inner chamber behind the first airtight seal is often at 12 or even at 15 degrees, meaning that the thermal gradient is gentle. The frame is thus warmer and the window offers better performance
- Opening inwards, not outwards. Many may gasp in disbelief that someone could have a window that opens this way, as they are concerned about not being able to use the inside window cill to display their precious Wedgwood artefacts. But, rest assured, this is not an issue. In Germany, window cills are used in the same way in as the UK. 99% of the time, the window is used only in the tilt position, thus allowing our cultural love of cluttered window cills to continue.
- Many German-style tilt and turn windows have thick, chunky frames. That’s simply the style in Germany. In a house with large openings, the strong engineered frames can allow for large maximum sizes. That said, however, often these are not suitable to retrofit into a UK home with normal windows. If the window is small, the frame size is still chunky and results in less glass. However, some of the Danish tilt and turn units offer slim frames, thus providing a happy medium ideal for UK houses.
Are your windows energy efficient?
There are a few different types of condensation. Ever noticed condensation around the edge of the glass near the frame on the inside? This is partly caused by cold air being deep inside the frame. A cold bridge is created, cooling the inside of the window frame. This is not good for energy efficiency, or for the air-tightness of your windows. Tilt and turn windows essentially shut like a bank vault in terms of their overall efficiency.
Want to test the energy efficiency of your windows? Here’s an easy trick. Take an incense stick around the frame of your window and float a line of smoke around the window. On windy days, you will see the smoke move around the window. You should also test the area between the wall and the window, underneath the window board (or internal window cill). If you see the smoke move, you know that you have air leakage from the outside into your home.
Our performance windows are enhanced by our German standards of installation. It’s not just about the window, it’s equally about how it’s installed. Indeed, our customers tell us that it is our understanding of construction, windows and doors which makes us so unique.
Replacing your windows with tilt and turn: What to look out for
Timber and composite tilt and turn windows are by far the most popular in the UK. But aluminium is considerably cheaper. Often, however, this is a lure, as many aluminium frames suffer from condensation, despite the inclusion of a thermal break. As a result, the window frame will become the cold part of the room. Our advice is to think long and hard before putting aluminium windows into a property.
Modern buildings are airtight, and both air quality and its moisture content must be managed. In countries where tilt and turn is popular, so is MHVR (Mechanical Ventilation with Heat Recovery: a continuous source of ventilation that extracts stale, moisture-laden air and resupplies filtered air back in). As a result, the need for trickle vents is avoided. It has always seemed ironic to us to spend a lot of money on new performance windows and then create a hole for ventilation. It is worth noting that building regulations require ventilation from one of those options.
Regulations, regulations, regulations…
When using tilt and turn windows from Europe, many self-builders get caught out by not buying windows that comply with UK regulations. In a new build property, windows and doors must be part Q compliant for security. It is wise to seek assistance from UK companies about this, who have UK-based staff and UK aftersales.
Horror stories of self-builders who try to buy windows directly from Estonian, Latvian or online German window shops are not uncommon and often result in windows being rejected by building control. Getting professional help on specification is essential to avoid this. Be wary of supply-only companies who don’t supply and fit as a single package. They usually don’t want to fit because they don’t have building experience and don’t want the risks: they would much rather you take them on.