Choosing patio doors - find out all the available solutions! Terrace systems: balcony doors, PSK, HST, folding doors - what distinguishes them - functional advantages and disadvantages

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It is hard to imagine a modern detached house without balcony doors. Terrace is an extension of the house, ideal in summer as a place for breakfasts or evening meetings with friends. Terrace doors allow us to open up the space and enjoy beautiful views inside the house. The window industry offers us many possibilities in this matter. Which solution is the best? Everything depends on our expectations. Let us introduce you to the options available.

Single patio doors
Single leaf balcony doors are the simplest solution and can be found in many houses and flats. Its advantage is, of course, low price and simple installation and operation. Classic single-leaf balcony doors are also characterised by high tightness.

The limitation of this solution is its size. The standard width of single-leaf PVC doors is 86.5cm.

This can make it difficult to place larger furniture. We also don’t get the desired effect of opening up to the outside space.

Single-leaf doors are best suited to smaller balconies. Single-winged doors are available in the following options: tilt and turn. In the case of single-wing balcony doors, we can apply a low threshold option, which will allow us to reduce architectural barriers, as well as to obtain a modern and more practical exit to the terrace.

Double patio doors
Another available and commonly chosen solution are double patio doors with a so-called movable post. Movable post means that this construction element is permanently connected with one of the wings, thanks to which after opening both wings we obtain free space. This definitely improves comfort, not only when moving around, but also when bringing larger furniture into the house.

In case of double doors with a movable post, it is worth mentioning that the part containing the movable post can only be opened without the tilt option.

The optimum size of a double-leaf balcony door with a movable mullion, made of standard PVC-U window sections should not exceed the dimensions S = 1.8m; H = 2.3m.

In theory, it is also possible to make double-leaf doors with a fixed mullion, but this solution is functionally impractical and therefore rarely encountered.

Tilt and slide balcony doors PSK
In response to the growing expectations of customers who want large glazing and comfort, systems such as PSK tilt and slide doors have been developed. In the case of classic balcony doors (described above), the sashes open towards the room, or in the opposite case of doors and windows in the Dutch system, space is needed for their complete unfolding. With the PSK solution, however, the movement of the sashes takes place parallel to the plane of the window. This obviously saves space in the interior.

PSK windows are tilted in the same way as traditional windows and the operation of this system is simple. However, in the case of large sizes it is not as smooth as with the HST solution, e.g. our child may have a problem with a large structure, weighing almost e.g. 150kg).
Another disadvantage is the lack of a low threshold, which is a big problem e.g. for people in wheelchairs.

The advantage of the PSK system is undoubtedly the lower cost, so if this aspect is key in your decision, you will probably find the PSK solution optimal.

Another advantage is the width of the structure, which if properly divided into three-quarter structures can exceed even 4m. In the case of height, around 2.3m is still recommended.

The movement of the sashes takes place on rails and trolleys, so precise installation of the structure is very important.

HST lift and slide balcony doors
HST balcony doors have become extremely popular in recent years. They are perfect for large glazed areas. Their undoubted advantage is also the possibility to create a structure with a 13mm threshold, i.e. the threshold is hidden in the floor. Such a solution obviously increases functionality and is ideal e.g. for people in wheelchairs.

In the case of HST doors, special hardware mechanisms make it possible to move huge wings with minimum force. Turning the handle down, from the closed position, raises the sash a few millimetres, releasing the gasket pressure and allowing the sashes to move freely.

The HST system allows you to create import glazing. The width, depending on the chosen opening scheme, can reach up to 6m. Light-filled rooms, closeness to nature, lack of barriers and freedom of space shaping are features for which we are willing to pay more.

The installation of HST doors requires appropriate skills and the use of professional equipment (e.g. a crane), as they are large and can exceed 400kg in weight. Modern solutions used in the window industry nowadays guarantee that heat loss is virtually negligible even with such constructions.

Opponents of large windows argue that such a large surface of glass means worse thermal insulation, and consequently higher heating costs. This is a myth. Glazing achieves better thermal insulation parameters (at the level of even Ug=0.4 W/m2K), whereas even a warm profile, achieves the thermal insulation at the level of Uf=0.79 W/m2K, that is weaker than glass. So it is not the glazing that causes heat loss.

Bigger glazing is an invitation to potential burglars? Once again we dispel the myth. In large HST constructions the glass panes must be thicker than in smaller frames, e.g. one pane of glass in a double-glazed unit will be 6mm and more instead of 4mm. Thicker glass has better thermal and acoustic insulation parameters, and at the same time is more difficult to break. It is also recommended to use PVB safety glass and packages such as 33.1 for such large glazings.

In addition, the use of fittings from reputable manufacturers, which can be certified in one of the burglary resistance classes, such as RC2, provides a guarantee of effective anti-burglary protection. It is also possible to install special opening sensors and connect them to the alarm system.

In HST type terrace doors we have a choice of different opening schemes. We have presented these methods in the graphic below. The first scheme, i.e., a double door with one movable leaf, with a right or left-hand variant, is the one most often chosen by customers. The last scheme presented, i.e. the four-door scheme with two middle opening wings, which allows to have a “garden” at home, gives us great possibilities.

Folding patio doors
Folding doors are a less popular solution than the ones presented above. They are most often used, for example, in winter gardens.

Fold&Slide doors usually consist of two parts: a casement (or tilt&turn) and two or more casements which, when shifted sideways, fold together like an accordion. It is possible to manufacture doors consisting of 3 to 8 leaves. A carriage moves in the threshold, on which the weight of the moving structure is transferred.

Their advantage is the possibility of installing a low threshold, useful when there are children, elderly or disabled people in the house. Another advantage is the space-saving and spacious passage when the door is fully opened.

Which solution to choose?
The answer to this question is not obvious. It all depends on the planned use and positioning of the balcony door in the house façade.
If we do not plan it before the construction begins, the size of the opening, expectations regarding functionality and the available budget will largely determine whether we will have single-leaf or double-leaf doors, PSK or HST.