A sliding door is a type of

door A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a ''doorway'' or ''portal''. A door's essential and primary purpose is to provide security b ...

which opens horizontally by sliding, usually horizontal to a wall. Sliding doors can be mounted either on top of a track below or be suspended from a track above. Some types slide into a space in the parallel wall in the direction of travel, rather than the door sliding along the outside of the parallel wall. There are several types of sliding doors, such as

pocket door A pocket door is a sliding door that, when fully open, disappears into a compartment in the adjacent wall. Pocket doors are used for architecture, architectural effect, or when there is no room for the swing of a hinged door. They can travel on r ...

sliding glass door A sliding glass door, patio door, or doorwall A sliding glass door, patio door, or doorwall is a type of predominantly glass sliding door, in architecture and construction, that is situated in an external wall to provide egress from a room an ...

s, center-opening doors, and bypass doors. Sliding doors are commonly used as

shower A shower is a place in which a person bathes under a spray of typically warm or hot water. Indoors, there is a drain in the floor. Most showers have temperature, spray pressure and adjustable showerhead nozzle. The simplest showers have a ...

doors, glass doors,

screen door A screen door can refer to a hinged storm door (cold climates) or hinged screen door (warm climates) covering an exterior door, or a screened sliding door used with sliding glass doors. In any case, the screen door incorporates screen mesh to blo ...

wardrobe A wardrobe or armoire or almirah is a standing closet used for storing clothes. The earliest wardrobe was a chest, and it was not until some degree of luxury was attained in regal palaces and the castles of powerful nobles that separate accomm ...

doors or in vans.

History

Sliding doors were used as early as the 1st century CE in

Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a letter ...

houses (as evidenced by archaeological finds in

Pompeii Pompeii (, ) was an ancient city located in what is now the ''comune'' of Pompei near Naples in the Campania region of Italy. Pompeii, along with Herculaneum and many villas in the surrounding area (e.g. at Boscoreale, Stabiae), was buried ...

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...

); however, there is no evidence to confirm that the Romans were the first humans to have invented or used sliding doors.

Sliding door gear

The mechanism used to operate a sliding door is called ''sliding door gear''. There are two standard types: top-hung or bottom rolling systems. Both types do not have a perfect seal. To reduce air- and smoke-tightness and improve sound insulation, brush seals are commonly used.

Top-hung sliding doors

The 'top-hung' system is most often used. The door is hung by two trolley hangers at the top of the door running in a concealed track; all the weight is taken by the hangers, making the door easier to move. At each end is a track stopper to absorb any impact made if the door is slammed and to hold the door in the open or closed position. All top-hung sliding door gear systems have a maximum weight limit per pair of trolley hangers. As the door is hung at the top from two points, it also needs a bottom track/stay roller to prevent it from swinging sideways. The most common type is called 'clear threshold guiding', a floor-fixed plastic guide about wide which is fixed below the door at the midpoint of its run. A groove is cut into the bottom of the door which runs over this guide, preventing lateral movement of the door. With a glass door, the panel runs through the guide as illustrated. Because the door is always engaged in the guide, when the door is open, the floor is clear; hence 'clear threshold'. The bottom of the doors are held in place on tracks. The rollers also have safety locks that prevent the doors from jumping off the tracks. Additional devices include soft-closers and dampeners, which make it easier to close the door gently. A popular top-hung sliding door type is the

barn door Stage lighting accessories are components manufactured for conventional (non-automated) stage lighting instruments. Most conventional fixtures are designed to accept a number of different accessories designed to assist in the modification of the ou ...

, inspired from countryside

barn A barn is an agricultural building usually on farms and used for various purposes. In North America, a barn refers to structures that house livestock, including cattle and horses, as well as equipment and fodder, and often grain.Allen G. ...

s, in modern homes of Scandinavian styles.

Bottom-rolling door gear

Sometimes a top-hung system cannot be used, as the weight of the door cannot be supported from above; in this case, a bottom-rolling system may be used. A bottom-rolling system consists of two rollers (sometimes called a sheave) at the bottom of the door running on a track, and two guides at the top running in a guide channel. As all the weight of the door is concentrated on the two bottom wheels, more force is needed to move the door than on a top-hung system.

Lift-and-slide door gear

A sliding door that is lifted from the frame during opening and closing is called a lift-and-slide door. This allows for a better seal, with less draught and better soundproofing.

Automatic sliding doors

Some sliding doors contain a motor and activation system to open them. These are called ''sliding door operators''. Automatic sliding doors are commonly found in offices and shop entrances. These doors contain a magnetic locking mechanism that automatically unlocks during emergencies.

Usage

Advantages of sliding doors are the small space requirements for door-opening, and their relative ease of automation. The mechanism is also secure, since it cannot be lifted out of its hinges. Sliding doors are commonly found as store, hotel, and office entrances, used in elevators, and used as patio doors, closet doors and room dividers. Sliding doors are also used in transportation, such as in vans and both overground and underground trains. Volkswagen used these doors in the Volkswagen Fridolin produced between 1964 and 1974.

References

External links

{{Commons category inline, bullet=none, Sliding doors Doors Italian inventions