Door hidden in a wall provide much more possibilities of interior arrangement than traditional door. Thanks to it one can e.g. connect the living room with kitchen, dining room or study room, for the time of family celebrations.

Sliding door, especially those with large door-wings, if need be, allow for easy and quick change of home scenery. It is like moving walls - by means of such door one can expose fragments of rooms, changing the climate of an interior or cover the entrance to rooms behind it.

Where to install
Between the hall and the living room. Large sliping door installed in this place allow to obtain a wide passage in a short time, thanks to which one may let in many invited guests in a convenitnt way. The door may be left open (without the ankiety that it might slam as a result of draught), in order to control the situation in a partially separated room - e.g. check whether the next guests arrived at the hall. Moreover, high "plasticity" of sliding door and variety of the offered patterns allow for original arrangement of a representative passage.
Between two rooms. Thanks to wide sliding door one can change the size, proportionsand functions of rooms. Opening the door between neighbouring rooms, one receives a large room. Living room combined with a dining room forms spacious interior for a family party. In children"s rooms connected together, younger children can play together and older - entertain their acquaintances and when the door is closed, they get their rooms back.
Between kitchen and living room. It is a perfect way of solving this difficult dilemma - open or closed kitchen. Depending on the need - when the door is open - the kitchen is a part of a large living room, where daily life of household members carries on, and when closed, it is separated as a closed room (thanks to which smells from cooking or kitchen noise are not spread throughout the apartment).
Between bedroom and wardrobe. In morning rush, wide access to wardrobes of both spouses provides to prepare for daily duties in agreement and in an effective way, and the possible mess left - hidden behind the door - does not damage harmony in bedroom.
In multi-functional rooms. Sliding door is a great idea when one wants to separate a part of a room for other purposes. In this way in a part of bedroom one may arrange a place for exercising, separate a fragment of a living room for work and to make a laundry in a part of bathroom.
In rooms for the disabled. Sliding door provides wide passage and do not take the space, which is required for people moving on wheelchairs. Additional advantage is easy incorporation of a drive to the sliding door and automatic opening or closing them by means of a remote control or a button on the wall.
In anteroom, which is usually a very crowded place - household members are passing by or guests are welcomed. Sliding door may be used for closing of built-in wardrobes, which do not occupy space as a traditional hanger for clothes or a cabinet for shoes. They are also more convenient when doors to neighbouring rooms are close to each other. Opening is collision-free, especially when hidden in a wall, whereas regular door usually collide in such situation and as a result, are quickly damaged.
In a larder, it saves the place, which is especially precious in small rooms. It allows for easy and quick access to hidden items, which are urgently needed, and allow for covering of places, which are not always in perfect order. Door with semi-transparent glass are useful in such places (e.g. satin or ornamented glass) - contours of items are visible through it, which allows for finding of the searched item in a short time but details, which we want to hide, remain invisible.

How does a door-leaf move?
Majority of sliding doors are system with a carrying rail on which door-leaves are suspended in carriages. Such a door-leaf has no contact with the floor so it may be finished at one"s discretion. Thresholds are not required in these systems.
Doors with more stable lower slideway are also available. They are used mainly in case when a door-leaf is large and heavy. The structure of slideway supported on a base can be less complicated - therefore, it is usually cheaper. The most economic one is the lower rail in form of "U" letter, inside which a door-leaf is moving on rollers. However, as dirt accumulates there easily, it is rather recommended to built-in wardrobes. In places, where people are walking, e.g. at the exit from living room, rails with convex track are rather used, on which a carriage with concave wheels.
Sliding door may be opened in one or two sides (two door-leaves are moving to the sides). Apart from regular door with one door-leaf, it is also possible to install telescopic door - then the door-leaves moving on two-track slideways may be freely moved, as in a wardrobe, or one door-leaf may be hidden behind another, and then moved together in one direction (so-called cascade). This solution is used often because it allows for decrease of the length of the slideway and dimensions of the cassette hidden in a wall (two door-leaves are next to each other in one cassette), and the required length of the threshold.
Two door-leaves moving in the opposite directions may also be installed in one cassette. This solution, also called the overlap system, allows for closing of two neighbouring rooms with sliding door. Solutions, which allow for synchronization of movement of door-leaves on the opposite sides of a door-way are also available (coupled system) - i.e. such coupling of both door-leaves in double door, that whilst moving of one door-leaf, the latter is moved too. It is assured by a system of steel lines, which are used to join the door-leaves together. Such a solution is usually used in door hidden in a wall - the system of lines is invisible then. The synchronizing mechanism may also be installed in on-wall doors - then it is usually hidden behind a masking frame.
Older and disabled people often choose the door with counterbalance (as in elevators). Counterbalance enables easier moving of a large door-leaf, compensating its weight. This solution is often used in doors hidden in a wall - counterbalance connected with the door by means of a steel line is also hidden in a cassette. It allows for automatic closing of open doors.
Another improvement is door with electric drive, where engine is started by means of a button on a wall or a remote control, which automatically moves a door-leaf. Such doors also should be equipped with a photocell, which protects against trapping by the closing door.

How is the door installed?
Door moving along the wall on a slideway installed on it or to the ceiling is the simplest solution, however it has some defects. In case of such doors, it is impossible to arrange furniture, shelves or paintings in its surrounding. Moreover, a moving door-leaf may be dangerous to children playing around it. If a doorway is wide, one may install door, which moves on a slideway fixed to a threshold. The door-leaf overlaps then on lateral transom or on a closed opening door-leaf.
The most convenient solution is door, which moves on a special cassette hidden in a wall - when opened, it "disappears" inside a wall, allowing for any free usage of this area. Producers offer ready-made cassettes adjusted for assembly in brick or cardboard-gypsum walls; their thickness usually amounts to 10 or 12,5 cm. Such a ready cassette for hiding of sliding door may also be affixed to the existing wall but one must remember that leap will be formed then and certain space in a room shall be occupied.
Instead of buying of a ready-made cassette, one may also make a suitable structure of gypsum-cardboard panels on a frame of aluminium sections (usually it is ca. 30% cheaper).
Caution! Door hidden in a wall should be planned already in the design of a new house or repair of an apartment, as they require an adequately longer threshold in the doorway in the structure wall or leaving a suitable gap in the partition wall, which shall be built up with a cassette.

What is it made of?
The most important elements of sliding door are door-leaves, slideways and carriages.
Door-leaves. As in traditional hinged door, may have the following structure:
- frame (panel) - door-leaves have visible structure of PVC profiles, aluminium or steel sections or door sills. The fill may be made of wood, wood-based panels, glass, PVC or aluminium panels or of a special fabric or blotting paper (popular solution in Japanese interior design);
- board - door-leaves have wooden structure (invisible), veneered with flat wood-based panels; it may also be composed of a panel made of glued wood or panels made of safe glass (hardened or laminated);
- board-panel - the door has invisible wooden structure but thanks to application of especially pressed millboards they look similar to panel doors.
Regardless of its structure, the door may be finished with colourless or colouring lacquers, painted in different colours, coated with monochromatic or wood-like foils, or decorated with a layer of veneer.
Door-leaves with glass are often used in sliding door. Depending on needs, the glass may be made of non-transparent glass (then the door is a barrier and provide intimacy to those, who stay in a particular room), or transparent (thanks to which one may optically combine rooms and household members have eye contact with one another; moreover, transparent glass allows for watching of space behind the door, e.g. plants in winter garden are visible from a living room).
Transparent glass is usually colourless or colourful float glass; non-transparent glass is usually made of ornamented or matt glass but it may also be a stained-glass window or colourful composition of fused glass (fusing). Laminated glass, inside which LED diodes in different colours are embedded, is also a novelty - it may be used as decorative or illuminating element. One may also use mirror panels, which - apart from non-transparency - provide optical enlargement of rooms.
Slideways. Upper rails (fixed to walls, ceilings, threshold or in a cassette hidden in a wall) may be made of steel or aluminium. The admissible weight of a door-leaf depends on their rigidity and resistance. The lightest door-leaves have a paper fill and the heaviest - made of glass (even if they seem really light, 10 mm thick glass panels, with the surface of 2 m2 weight up to 50 kg). Lower rails are usually made of metal and these made of plastic with a metal rail are not used so often. They are installed on the existing floor (e.g. in built-in wardrobes) or "embedded" in it, in order not to hinder the movement (e.g. door to a living room).
Slideways may have one or two tracks. One-track slideways allow for installation of one or two door-leaves, which touch when closed. Their length ought to be equal at least to double width of door-leaves, so that the door may be opened freely. Two-track slideways allow for installation of several door-leaves, which may overlap whilst closing.
Carriages. They allow for moving of a door-leaf. Structure of a carriage depends on weight of door and on convenience, which one wants to obtain whilst moving of door.
A door-leaf is fixed to carriages by means of adjustable holders and bearing wheels guarantee quiet and long, failure-free operation. Doors, in which axles of wheels are mounted in bearings or move on a teflon spindle, move the quickest and smoothly.
Wheels may be made of steel (uncoated or covered with teflon or with a ring made of special rubber or silicone) or of plastic (often of hard nylon). Carriages usually move on two or four wheels. Sometimes, instead of carriages, large decorative steel wheels are used, which are moving on the lower rail. They are designed for glass door in modern interiors.

Text: Michał Mikołajski; the text originates from the web portal Gazeta.pl - www.gazeta.pl © Agora SA