Door

A door is a moving structure used to block off, and allow access to, an entrance to or within an enclosed space, such as a building or vehicle. Doors normally consist of a panel that swings on hinges on the edge, but there are also doors that slide or spin inside of a space. Similar exterior structures to doors are called gates.

Typically, doors have an interior side that faces the inside of a space and an exterior side that faces the outside of that space. In many cases the interior side of a door mostly matches its exterior side, but in some other cases there are sharp contrasts between the two sides, such as in the case of a vehicle door.

When open, doors admit people, animals, ventilation or light. The door is used to control the physical atmosphere within a space by enclosing the air drafts, so that interiors may be more effectively heated or cooled. Maybe, people open and close doors as a sign of privacy. Example: A door might be closed and someone is inside, because they are feeling a sort of violation letting people in at that time. Doors are significant in preventing the spread of fire. They also act as a barrier to noise. Many doors are equipped with locking mechanisms to allow entrance to certain people and keep out others. As a form of courtesy and civility, people often knock before opening a door and entering a room.

Doors are used to screen areas of a building for aesthetics, keeping formal and utility areas separate. Doors also have an aesthetic role in creating an impression of what lies beyond. Doors are often symbolically endowed with ritual purposes, and the guarding or receiving of the keys to a door, or being granted access to a door can have special significance.^[1] Similarly, doors and doorways frequently appear in metaphorical or allegorical situations, literature and the arts, often as a portent of change.

History

The earliest in records are those represented in the paintings of the Egyptian tombs, in which they are shown as single or double doors, each in a single piece of wood. Doors were once believed to be the literal doorway to the afterlife, and some doors leading to important places included designs of the afterlife. In Egypt, where the climate is intensely dry, there would be no fear of their warping, but in other countries it would be necessary to frame them, which according to Vitruvius (iv. 6.) was done with stiles (sea/si) and rails (see: Frame and panel): the spaces enclosed being filled with panels (tympana) let into grooves made in the stiles and rails. The stiles were the vertical boards, one of which, tenoned or hinged, is known as the hanging stile, the other as the middle or meeting stile. The horizontal cross pieces are the top rail, bottom rail, and middle or intermediate rails. The most ancient doors were made timber, such as those referred to in the Biblical depiction of King Solomon's temple being in olive wood (I Kings vi. 31-35), which were carved and overlaid with gold. The doors dwelt upon in Homer would appear to have been cased in silver or brass. Besides olive wood, elm, cedar, oak and cypress were used. A 5,000-year-old door has been found by archaeologists in Switzerland.^[2]

All ancient doors were hung by pivots at the top and bottom of the hanging stile which worked in sockets in the lintel and sill, the latter being always in some hard stone such as basalt or granite. Those found at Nippur by Dr. Hilprecht dating from 2000 B.C. were in dolerite. The tenons of the gates at Balawat were sheathed with bronze (now in the British Museum). These doors or gates were hung in two leaves, each about 8 ft 4 in (2.54 m) wide and 27 ft (8.2 m). high; they were encased with bronze bands or strips, 10 in. high, covered with repouss decoration of figures, etc. The wood doors would seem to have been about 3 in. thick, but the hanging stile was over 14 inches (360 mm) diameter. Other sheathings of various sizes in bronze have been found, which proves this to have been the universal method adopted to protect the wood pivots. In the Hauran in Syria, where timber is scarce the doors were made in stone, and one measuring 5 ft 4 in (1.63 m) by 2 ft 7 in (0.79 m) is in the British Museum; the band on the meeting stile shows that it was one of the leaves of a double door. At Kuffeir near Bostra in Syria, Burckhardt found stone doors, 9 to 10 ft (3.0 m). high, being the entrance doors of the town. In Etruria many stone doors are referred to by Dennis.

The ancient Greek and Roman doors were either single doors, double doors, triple doors, sliding doors or folding doors, in the last case the leaves were hinged and folded back. In Eumachia, is a painting of a door with three leaves. In the tomb of Theron at Agrigentum there is a single four-panel door carved in stone. In the Blundell collection is a bas-relief of a temple with double doors, each leaf with five panels. Among existing examples, the bronze doors in the church of SS. Cosmas and Damiano, in Rome, are important examples of Roman metal work of the best period; they are in two leaves, each with two panels, and are framed in bronze. Those of the Pantheon are similar in design, with narrow horizontal panels in addition, at the top, bottom and middle. Two other bronze doors of the Roman period are in the Lateran Basilica.

The Greek scholar Heron of Alexandria created the earliest known automatic door in the 1st century AD during the era of Roman Egypt.^[3] The first foot-sensor-activated automatic door was made in China during the reign of Emperor Yang of Sui (r. 604–618), who had one installed for his royal library.^[3] The first automatic gate operators were later created in 1206 by Arab inventor Al-Jazari.^[4]

Copper and its alloys were integral in medieval architecture. The doors of the church of the Nativity at Bethlehem (6th century) are covered with plates of bronze, cut out in patterns. Those of Hagia Sophia at Constantinople, of the 8th and 9th century, are wrought in bronze, and the west doors of the cathedral of Aix-la-Chapelle (9th century), of similar manufacture, were probably brought from Constantinople, as also some of those in St. Marks, Venice. The bronze doors on the Aachen Cathedral in Germany date back to about AD 800. Bronze baptistery doors at the Cathedral of Florence were completed in 1423 by Ghiberti.^[5] (For more information, see: Copper in architecture).

Of the 11th and 12th centuries there are numerous examples of bronze doors, the earliest being one at Hildesheim, Germany (1015). The Hildesheim design affected the concept of Gniezno door in Poland. Of others in South Italy and Sicily, the following are the finest: in Sant Andrea, Amalfi (1060); Salerno (1099); Canosa (1111); Troia, two doors (1119 and 1124); Ravello (1179), by Barisano of Trani, who also made doors for Trani cathedral; and in Monreale and Pisa cathedrals, by Bonano of Pisa. In all these cases the hanging stile had pivots at the top and bottom. The exact period when the hinge was substituted is not quite known, but the change apparently brought about another method of strengthening and decorating doors, viz, with wrought-iron bands of infinite varieties of design. As a rule three bands from which the ornamental work springs constitute the hinges, which have rings outside the hanging stiles fitting on to vertical tenons run into the masonry or wooden frame. There is an early example of the 12th century in Lincoln; in France the metal work of the doors of Notre Dame at Paris is perhaps the most beautiful in execution, but examples are endless throughout France and England.

Returning to Italy, the most celebrated doors are those of the Battistero di San Giovanni (Florence), which together with the door frames are all in bronze, the borders of the latter being perhaps the most remarkable: the modeling of the figures, birds and foliage of the south doorway, by Andrea Pisano (1330), and of the east doorway by Ghiberti (1425–1452), are of great beauty; in the north door (1402–1424) Ghiberti adopted the same scheme of design for the paneling and figure subjects in them as Andrea Pisano, but in the east door the rectangular panels are all filled, with bas-reliefs, in which Scripture subjects are illustrated with innumerable figures, these being probably the gates of Paradise of which Michelangelo speaks.

The doors of the mosques in Cairo were of two kinds; those which, externally, were cased with sheets of bronze or iron, cut out in decorative patterns, and incised or inlaid, with bosses in relief; and those in wood, which were framed with interlaced designs of the square and diamond, this latter description of work being Coptic in its origin. The doors of the palace at Palermo, which were made by Saracenic workmen for the Normans, are fine examples and in good preservation. A somewhat similar decorative class of door to these latter is found in Verona, where the edges of the stiles and rails are beveled and notched.

In the Renaissance period the Italian doors are quite simple, their architects trusting more to the doorways for effect; but in France and Germany the contrary is the case, the doors being elaborately carved, especially in the Louis XIV and Louis XV periods, and sometimes with architectural features such as columns and entablatures with pediment and niches, the doorway being in plain masonry. While in Italy the tendency was to give scale by increasing the number of panels, in France the contrary seems to have been the rule; and one of the great doors at Fontainebleau, which is in two leaves, is entirely carried out as if consisting of one great panel only.

The earliest Renaissance doors in France are those of the cathedral of St. Sauveur at Aix (1503). In the lower panels there are figures 3 ft (0.91 m). high in Gothic niches, and in the upper panels a double range of niches with figures about 2 ft (0.61 m). high with canopies over them, all carved in cedar. The south door of Beauvais Cathedral is in some respects the finest in France; the upper panels are carved in high relief with figure subjects and canopies over them. The doors of the church at Gisors (1575) are carved with figures in niches subdivided by classic pilasters superimposed. In St. Maclou at Rouen are three magnificently carved doors; those by Jean Goujon have figures in niches on each side, and others in a group of great beauty in the center. The other doors, probably about forty to fifty years later, are enriched with bas-reliefs, landscapes, figures and elaborate interlaced borders.

NASA's Vehicle Assembly Building at the Kennedy Space Center contains the four largest doors. The Vehicle Assembly Building was originally built for the assembly of the Apollo missions' Saturn vehicles and was then used to support Space Shuttle operations. Each of the four doors are 139 meters (456 feet) high.^[6]

The oldest door in England can be found in Westminster Abbey and dates from 1050.^[7] In England in the 17th century the door panels were raised with bolection or projecting moldings, sometimes richly carved, round them; in the 18th century the moldings worked on the stiles and rails were carved with the egg and tongue ornament.

Design and styles

There are many kinds of doors, with different purposes. The most common type is the single-leaf door, which consists of a single rigid panel that fills the doorway. There are many variations on this basic design, such as the double-leaf door or double door and French windows, which have two adjacent independent panels hinged on each side of the doorway.

• A half door or Dutch door^[8] or stable door is divided in half horizontally. Traditionally the top half can be opened to allow a horse or other animal to be fed, while the bottom half remains closed to keep the animal inside. This style of door has been adapted for homes.
• Saloon doors are a pair of lightweight swing doors often found in public bars, and especially associated with the American west. Saloon doors, also known as cafe doors, often use bidirectional hinges that close the door regardless of which direction it is opened by incorporating springs. Saloon doors that only extend from knee-level to chest-level are known as batwing doors.

• A blind door, Gibb door, or jib door has no visible trim or operable components. It is designed to blend with the adjacent wall in all finishes, and visually to be a part of the wall, a disguised door.^[9]
• A French door consists of a frame around one or more transparent or translucent panels (called lights or lites) that may be installed singly, in matching pairs, or even as series. A matching pair of these doors is called a French window, as it resembles a door-height casement window. When a pair of French doors is used as a French window, the application does not generally include a central mullion (as do some casement window pairs), thus allowing a wider unobstructed opening. The frame typically requires a weather strip at floor level and where the doors meet to prevent water ingress. An espagnolette bolt may allow the head and foot of each door to be secured in one movement. The slender window joinery maximizes light into the room and minimizes the visual impact of the doorway joinery when considered externally. The doors of a French window often open outward onto a balcony, porch, or terrace and they may provide an entrance to a garden.
• A louvred door has fixed or movable wooden fins (often called slats or louvers) which permit open ventilation while preserving privacy and preventing the passage of light to the interior. Being relatively weak structures, they are most commonly used for wardrobes and drying rooms, where security is of less importance than good ventilation, although a very similar structure is commonly used to form window shutters. Double louvred doors were introduced into Seagate, built in Florida in 1929 by Gwendolyn and Powel Crosley, that provided the desired circulation of air with an added degree of privacy in that it is impossible to see through the fins in any direction.
• A composite door is a single leaf door that can be solid or with glass, and is usually filled with high density foam. In the United Kingdom, it is common for composite doors to be certified to BS PAS 23/24^[10] and be compliant with Secured by Design, an official UK police initiative.
• A steel security door is one which is made from strong steel, often for use on vaults and safe rooms to withstand attack. These may also be fitted with wooden outer panels to resemble standard internal and external doors.^[11]
• A flush door is a completely smooth door, having plywood or MDF fixed over a light timber frame, the hollow parts of which are often filled with a cardboard core material. Skins can also be made out of hardboards, the first of which was invented by William H Mason in 1924. Called Masonite, its construction involved pressing and steaming wood chips into boards. Flush doors are most commonly employed in the interior of a dwelling, although slightly more substantial versions are occasionally used as exterior doors, especially within hotels and other buildings containing many independent dwellings.
• A moulded door has the same structure as that of flush door. The only difference is that the surface material is a moulded skin made of MDF. Skins can also be made out of hardboards.
• A ledge and brace door is made from multiple vertical planks fixed together by two horizontal planks (the ledges) and kept square by a diagonal plank (the brace).
• A wicket door is a pedestrian door built into a much larger door allowing access without requiring the opening of the larger door. Examples might be found on the ceremonial door of a cathedral or in a large vehicle door in a garage or hangar.
• A bifold door is a unit that has several sections, folding in pairs. Wood is the most common material, and doors may also be metal or glass. Bifolds are most commonly made for closets, but may also be used as units between rooms. Bi-fold doors are essentially now doors that let the outside in. They open in concert; where the panels fold up against one another and are pushed together when opened. The main door panel (often known as the traffic door) is accompanied by a stack of panels that fold very neatly against one another when opened fully, which almost look like room dividers.^[12]
• A sliding glass door, sometimes called an Arcadia door or patio door, is a door made of glass that slides open and sometimes has a screen (a removable metal mesh that covers the door).
• Australian doors are a pair of plywood swinging doors often found in Australian public houses. These doors are generally red or brown in color and bear a resemblance to the more formal doors found in other British Colonies' public houses.
• A false door is a wall decoration that looks like a door. In ancient Egyptian architecture, this was a common element in a tomb, the false door representing a gate to the afterlife. They can also be found in the funerary architecture of the desert tribes (e.g., Libyan Ghirza).

• Design and styles
• 
  A decorated door from the Namdroling Monastery, southern India
• 
  A carved cedar door in the Great Mosque of Kairouan (the Mosque of Uqba), in Tunisia
• 
  Door in rural Punjab
• 
  A French window, known as patio door in UK, and portafinestra in Italy, where it is a common window-door type
• 
  Open internal door in a Shaker public building
• 
  Front door of a house with typical door furniture: a letter box, door knocker, a latch and two locks

Types of mechanism

Hinged doors

Most doors are hinged along one side to allow the door to pivot away from the doorway in one direction, but not the other. The axis of rotation is usually vertical. In some cases, such as hinged garage doors, the axis may be horizontal, above the door opening.

Doors can be hinged so that the axis of rotation is not in the plane of the door to reduce the space required on the side to which the door opens. This requires a mechanism so that the axis of rotation is on the side other than that in which the door opens. This is sometimes the case in trains or airplanes, such as for the door to the toilet, which opens inward.

A swing door has special double-action hinges that allow it to open either outwards or inwards, and is usually sprung to keep it closed.

A selfbolting door has special hinges that permit the panel leaf to move laterally, so that the door itself becomes a giant bolt for better security. The selfbolting door principle can be used both for hinged doors as for rotating doors, as well as up-and-over doors (in the latter case, the bolts are then placed at top and bottom rather than at the sides).

French doors are derived from an original French design called the casement door. It is a door with lites where all or some panels would be in a casement door. A French door traditionally has a moulded panel at the bottom of the door. It is called a French window when used in a pair as double-leaved doors with large glass panels in each door leaf, and in which the doors may swing out (typically) as well as in.

A Mead door, developed by S Mead of Leicester, swings both ways. It is susceptible to forced entry due to its design.

A Dutch door or stable door consists of two halves. The top half operates independently from the bottom half. A variant exists in which opening the top part separately is possible, but because the lower part has a lip on the inside, closing the top part, while leaving the lower part open, is not.

A garden door resembles a French window (with lites), but is more secure because only one door is operable. The hinge of the operating door is next to the adjacent fixed door and the latch is located at the wall opening jamb rather than between the two doors or with the use of an espagnolette bolt.

Sliding doors

It is often useful to have doors which slide along tracks, often for space or aesthetic considerations.

A bypass door is a door unit that has two or more sections. The doors can slide in either direction along one axis on parallel overhead tracks, sliding past each other. They are most commonly used in closets, in order to access one side of the closet at a time. The doors in a bypass unit will overlap slightly when viewed from the front, in order not to have a visible gap between them.

Doors which slide between two wall panels are called pocket doors.

Sliding glass doors are common in many houses, particularly as an entrance to the backyard. Such doors are also popular for use for the entrances to commercial structures, although they are not counted as fire exit doors. The door that moves is called the "active leaf", while the door that remains fixed is called the "inactive leaf".

Rotating doors

A revolving door has several wings or leaves, generally four, radiating from a central shaft, forming compartments that rotate about a vertical axis. A revolving door allows people to pass in both directions without colliding, and forms an airlock maintaining a seal between inside and out.

A pivot door, instead of hinges, is supported on a bearing some distance away from the edge, so that there is more or less of a gap on the pivot side as well as the opening side. In some cases the pivot is central, creating two equal openings.

High-speed door

A high-speed door is a very fast door some with opening speeds of up to 4 m/s, mainly used in the industrial sector where the speed of a door has an effect on production logistics, temperature and pressure control. High Speed Clean Room Doors are used in Pharmaceutical industries for the special curtain and stainless steel frames. They guarantee the tightness of all accesses. The powerful high-speed doors have a smooth surface structure and no protruding edges. Therefore, they can be easily cleaned and depositing of particles is largely excluded. High-speed doors are made to handle a high number of openings, generally more than 200000 a year. They need to be built with heavy duty parts and counterbalance systems for speed enhancement and emergency opening function. The door curtain was originally made of PVC, but was later also developed in aluminium and acrylic glass sections. High Speed refrigeration and cold room doors with excellent insulation values was also introduced with the Green and Energy saving requirements.

In North America, the Door and Access Systems Manufacturing Association (DASMA) defines high-performance doors as non-residential, powered doors, characterized by rolling, folding, sliding or swinging action, that are either high-cycle (minimum 100 cycles/day) or high-speed (minimum 20 inches(508 mm)/second), and two out of three of the following: made-to-order for exact size and custom features, designed to be able to withstand equipment impact (break-away if accidentally hit by vehicle) or designed to sustain heavy usage with minimal maintenance.

Automatic

Automatically opening doors are powered open and closed either by electricity, spring, or both. There are several methods by which an automatically opening door is activated:

1. A sensor detects traffic is approaching. Sensors for automatic doors are generally:
   • A pressure sensor – e.g., a floor mat which reacts to the pressure of someone standing on it.
   • An infrared curtain or beam which shines invisible light onto sensors; if someone or something blocks the beam the door is triggered open.
   • A motion sensor which uses low-power microwave radar for the same effect.
   • A remote sensor (e.g. based on infrared or radio waves) can be triggered by a portable remote control, or is installed inside a vehicle. These are popular for garage doors.
2. A switch is operated manually, perhaps after security checks. This can be a push button switch or a swipe card.
3. The act of pushing or pulling the door triggers the open and close cycle. These are also known as power-assisted doors.

In addition to activation sensors automatically opening doors are generally fitted with safety sensors. These are usually an infrared curtain or beam, but can be a pressure mat fitted on the swing side of the door. The purpose of the safety sensor is to prevent the door from colliding with an object in its path by stopping or slowing its motion.A mechanism is set in modern automatic doors to ensure that door will be in open state in case of power failure.

Others

Up-and-over or overhead doors are often used in garages. Instead of hinges it has a mechanism, often counterbalanced or sprung, that allows it to be lifted so that it rests horizontally above the opening. A roller shutter or sectional overhead door is one variant of this type.

A tambour door or roller door is an up-and-over door made of narrow horizontal slats and "rolls" up and down by sliding along vertical tracks and is typically found in entertainment centres and cabinets.

Inward opening doors are doors that can only be opened (or forced open) from outside a building. Such doors pose a substantial fire risk to occupants of occupied buildings when they are locked. As such doors can only be forced open from the outside, building occupants would be prevented from escaping. In commercial and retail situations manufacturers have included in the design a mechanism that allows an inward opening door to be pushed open outwards in the event of an emergency (which is often a regulatory requirement). This is known as a 'breakaway' feature. Pushing the door outward at its closed position, through a switch mechanism, disconnects power to the latch and allows the door to swing outward. Upon returning the door to the closed position, power is restored.

Rebated doors, a term chiefly used in Britain, are double doors having a lip or overlap (i.e. a Rabbet) on the vertical edge(s) where they meet. Fire-rating can be achieved with an applied edge-guard or astragal molding on the meeting stile, in accordance with the American Fire door.

Evolution Door is a trackless door that moves in the same closure level as a sliding door. The system is an invention of the Austrian artist Klemens Torggler. From the technical point of view the Evolution Door is a further development (evolution) of the Drehplattentür that normally consists of two rotatable, connected panels which move to each other when opening.^[13]

Applications

Architectural doors have numerous general and specialized uses. Doors are generally used to separate interior spaces (closets, rooms, etc.) for convenience, privacy, safety, and security reasons. Doors are also used to secure passages into a building from the exterior, for reasons of climate control and safety.

Doors also are applied in more specialized cases:

• A Blast-proof door is constructed to allow access to a structure as well as to provide protection from the force of explosions.
• A garden door is any door that opens to a backyard or garden. This term is often used specifically for French windows, double French doors (with lites instead of panels), in place of a sliding glass door. The term also may refer to what is known as patio doors.
• A jib door is a concealed door, whose surface reflects the moldings and finishes of the wall. These were used in historic English houses, mainly as servants' doors.
• A pet door (also known as a cat flap or dog door) is an opening in a door to allow pets to enter and exit without the main door's being opened. It may be simply covered by a rubber flap, or it may be an actual door hinged on the top that the pet can push through. Pet doors may be mounted in a sliding glass door as a new (permanent or temporary) panel. Pet doors may be unidirectional, only allowing pets to exit. Additionally, pet doors may be electronic, only allowing animals with a special electronic tag to enter.
• A trapdoor is a door that is oriented horizontally in a ceiling or floor, often accessed via a ladder.
• A water door or water entrance, such as those used in Venice, Italy, is a door leading from a building built on the water, such as a canal, to the water itself where, for example, one may enter or exit a private boat or water taxi.^[14][15]

^[16]

Construction and components

Panel doors

Panel doors, also called stile and rail doors, are built with frame and panel construction. EN 12519 is describing the terms which are officially used in European Member States. The main parts are listed below:

• Stiles – Vertical boards that run the full height of a door and compose its right and left edges. The hinges are mounted to the fixed side (known as the "hanging stile"), and the handle, lock, bolt or latch are mounted on the swinging side (known as the "latch stile").
• Rails – Horizontal boards at the top, bottom, and optionally in the middle of a door that join the two stiles and split the door into two or more rows of panels. The "top rail" and "bottom rail" are named for their positions. The bottom rail is also known as "kick rail". A middle rail at the height of the bolt is known as the "lock rail", other middle rails are commonly known as "cross rails".
• Mullions – Smaller optional vertical boards that run between two rails, and split the door into two or more columns of panels, the term is used sometimes for verticals in doors, but more often (UK and Australia) it refers to verticals in windows.
• Muntin – Optional vertical members that divide the door into smaller panels.
• Panels – Large, wider boards used to fill the space between the stiles, rails, and mullions. The panels typically fit into grooves in the other pieces, and help to keep the door rigid. Panels may be flat, or in raised panel designs. Can be glued in or stay as a floating panel.
• Light or Lite – a piece of glass used in place of a panel, essentially giving the door a window.

Plank and batten doors

Plank and batten doors are an older design consisting primarily of vertical slats:

• Planks – Vertical boards that extend the full height of the door, and are placed side by side filling the door's width.
• Battens – Smaller slats that extend horizontally across the door which the planks are affixed to. The battens hold the planks together. Sometimes a long diagonal slat or two are also implemented to prevent the door from skewing. On some doors, especially antique ones, the battens are replaced with iron bars that are often built into the hinges as extensions of the door-side plates.

Ledged and braced doors

This type consists of vertical tongue and grooved boards held together with battens and diagonal braces.

Impact-resistant doors

Impact-resistant doors have rounded stile edges to dissipate energy and minimize edge chipping, scratching and denting. The formed edges are often made of an engineered material such as Acrovyn. Impact-resistant doors excel in high traffic areas such as hospitals, schools, and hotels.

Frame and filled doors

This type consists of a solid timber frame, filled on one face, face with Tongue and Grooved boards. Quite often used externally with the boards on the weather face.

Flush doors

Many modern doors, including most interior doors, are flush doors:

• Stiles and rails – As above, but usually smaller. They form the outside edges of the door.
• Core material: Material within the door used simply to fill space, provide rigidity and reduce drumminess.
  • Hollow-core – Often consists of a lattice or honeycomb made of corrugated cardboard, or thin wooden slats. Can also be built with staggered wooden blocks. Hollow-core flush doors are commonly used as interior doors.
    • Lock block – A solid block of wood mounted within a hollow-core flush door near the bolt to provide a solid and stable location for mounting the door's hardware.
  • Stave-core – Consists of wooden slats stacked upon one another in a manner similar to a plank & batten door (though the slats are usually thinner) or the wooden-block hollow-core (except that the space is entirely filled).
  • Solid-core – Can consist of low-density particle board or foam used to completely fill the space within the door. Solid-core flush doors (especially foam-core ones) are commonly used as exterior doors because they provide more insulation and strength.
• Skin – The front and back faces of the door are then covered with wood veneer, thin plywood, sheet metal, fiberglass, or vinyl. The wooden materials are usually layered with the grain alternating direction between layers to prevent warping. Fiberglass and metal-faced doors are sometimes given a layer of cellulose so that they may be stained to look like wood.

Moulded doors

• Stiles and rails – As above, but usually smaller. They form the outside edges of the door.
• Core material: Material within the door used simply to fill space, provide rigidity and reduce druminess.
  • Hollow-core – Often consists of a lattice or honeycomb made of corrugated cardboard, extruded polystyrene foam, or thin wooden slats. Can also be built with staggered wooden blocks. Hollow-core molded doors are commonly used as interior doors.
    • Lock block – A solid block of wood mounted within a hollow-core flush door near the bolt to provide a solid and stable location for mounting the door's hardware.
  • Stave-core – Consists of wooden slats stacked upon one another in a manner similar to a plank & batten door (though the slats are usually thinner) or the wooden-block hollow-core (except that the space is entirely filled).
  • Solid-core – Can consist of low-density particle board or foam used to completely fill the space within the door. Solid-core flush doors (especially foam-core ones) are commonly used as exterior doors because they provide more insulation and strength.
• Skin – The front and back faces of the door are covered with HDF / MDF skins.

Swing direction

Door swings For most of the world, door swings, or handing, are determined while standing on the outside or less secure side of the door while facing the door (i.e., standing on the side requiring a key to open, going from outside to inside, or from public to private).

It is especially important to get the hand and swing correct on exterior doors, as the transom is usually sloped and sealed to resist water entry, and to properly drain. In some custom millwork (or with some master carpenters), the manufacture or installer will bevel the leading edge (the first edge to meet the jamb as the door is closing) so that the door fits tight without binding. Specifying an incorrect hand or swing will cause the door to bind, not close properly or leak (for exterior doors). Fixing this specification error will be expensive or time consuming.

In North America, many doors now come with factory-installed hinges, pre-hung on the jamb and sills.

While facing the door from the outside or less secure side, if the hinge is on the right side of the door, the door is "Right handed"; or if the hinge is on the left, it is "Left handed".

If the door swings toward you, it is "Reverse swing"; or if the door swings away from you, it is "Normal swing".

In other words:

• Left hand hinge (LHH): Standing outside (or on the less secure side, or on the public side of the door), the hinges are on the left and the door opens in (away from you).
• Right hand hinge (RHH): Standing outside (or on the less secure side), the hinges are on the right and the door opens in (away from you).
• Left hand reverse (LHR): Standing outside the house (or on the less secure side), the hinges are on the left, knob on right, on opening the door it swings towards you (i.e. the door swings open towards the outside, or "outswing")
• Right hand reverse (RHR): Standing outside the house (i.e. on the less secure side), the hinges are on the right, knob on left, opening the door by pulling the door towards you (i.e. open swings to the outside, or "outswing")

In Australia, the "refrigerator rule" applies, and a refrigerator door is not opened from the inside. If the hinges are on the right then it is a right hand (or right hung) door. (Australian Standards for Installation of Timber Doorsets, AS 1909–1984 pg 6.)

In Europe one of the oldest DIN standard applies: DIN 107 "Building construction; identification of right and left side" (first 1922-05, current 1974-04) defines that doors are categorized from the side where the door hinges can be seen. If the hinges are on the left, it is a DIN Left door (DIN links, DIN gauche), if the hinges are on the right, it is a DIN Right door (DIN rechts, DIN droite). The DIN Right and DIN Left marking are also used to categorize matching installation material such as mortise locks (referenced in DIN 107). The European Standard DIN EN 12519 "Windows and pedestrian doors. Terminology" includes these definitions of orientation.

In public buildings, exterior doors should open to the outside in order to comply with any fire codes that may be in force in that jurisdiction. If the door opens inward and there is a fire, there can be a crush of people who run for the door and they will not be able to open it.

Types

New exterior doors are largely defined by the type of materials they are made from: wood, steel, fiberglass, UPVC/vinyl, aluminum, composite, glass (patio doors)...

Wooden doors – including solid wood doors – are a top choice for many homeowners, largely because of the aesthetic qualities of wood. Many wood doors are custom-made, but they have several downsides: their price, their maintenance requirements (regular painting and staining) and their limited insulating value ^[17] (R-5 to R-6, not including the effects of the glass elements of the doors).

Steel doors are another major type of residential front doors; most of them come with a polyurethane or other type of foam insulation core – a critical factor in a building's overall comfort and efficiency.

Most modern exterior walls are designed to provide thermal insulation and energy efficiency, which can be indicated by the Energy Star label or the Passive House standards. And that’s where premium composite (including steel doors with a thick core of polyurethane or other foam), fiberglass and vinyl doors become interesting. From a thermal standpoint, these doors can benefit from the materials they are made from.

Insulation and weatherstrips

But there are very few door models with an R-value close to 10 (which is far less than the R-40 walls or the R-50 ceilings of super-insulated buildings – Passive Solar and Zero Energy Buildings). Typical doors are not thick enough to provide very high levels of energy efficiency.

Many doors may have good R-values at their center, but their overall energy efficiency is reduced because of the presence of glass and reinforcing elements, or because of poor weatherstripping and the way the door is manufactured.

Door weatherstripping is particularly important for energy efficiency. German-made Passive House doors use multiple weatherstrips, including magnetic strips, to meet higher standards. These weatherstrips are critical to reduce to a minimum energy losses due to air leakage.

Dimensions

United States

The standard door sizes in the US run along 2" increments. Customary sizes have a height of 78" (1981 mm) or 80" (2032 mm) and a width of 18" (472 mm), 24" (610 mm), 26" (660 mm), 28" (711 mm), 30" (762 mm) or 36" (914 mm).^[18] Most residential passage (room to room) doors are 30" x 80" (762 mm x 2032 mm).

A standard US residential (exterior) door size is 36" x 80" (91 x 203 cm). Interior doors for wheelchair access must also have a minimum width of 3'-0" (91 cm). Residential interior doors are often somewhat smaller being 6'-8" high, as are many small stores, offices, and other light commercial buildings. Larger commercial, public buildings and grand homes often use doors of greater height. Older buildings often have smaller doors.

Thickness: Most pre-fabricated doors are 1 3/8" thick (for interior doors) or 1 3/4" (exterior).

Closets: small spaces such as closets, dressing rooms, half-baths, storage rooms, cellars, etc. often are accessed through doors smaller than passage doors in one or both dimensions but similar in design.

Garages: Garage doors are generally 7'-0" or 8'-0" wide for a single-car opening. Two car garage doors (sometimes called double car doors) are a single door 16'-0". Because of size and weight these doors are usually sectional. That is split into four or five horizontal sections so that they can be raised more easily and don't require a lot of additional space above the door when opening and closing. There are single piece double garage doors found in some older homes. circa 1950's

Europe

The standard DIN doors are defined in DIN 18101 (published 1955-07, 1985-01, 2014-08). The door sizes are also given in the construction standard for wooden door panels (DIN 68706-1). The DIN commission was also responsible for the harmonized European standard DIN EN 14351-1 for exterior doors and DIN EN 14351-2 for interior doors (published 2006-07, 2010-08), which defines the requirements for the CE marking giving standard sizes by examples in the appendix.

The DIN 18101 standard has a normative size (Nennmaß) slightly larger than the panel size (Türblatt) as the standard derives the panel sizes from the normative size being different single door vs double door and molded vs unmolded doors. The DIN 18101/1985 defines interior single molded doors to have a common panel height of 1985 mm (normativ height 2010 mm) at panel widths of 610 mm, 735 mm, 860 mm, 985 mm, 1110 mm, plus a larger door panel size of 1110 mm x 2110 mm.^[19] The newer DIN 18101/2014 drops the definition of just five standard door sizes in favor of a basic raster running along 125 mm increments where the height and width are independent. The panel width may be in the range 485 mm to 1360 mmm, and the height may be in the range of 1610 mm to 2735 mm.^[20] The most common interior door is 860 mm x 1985 mm (33.8" x 78.1").

Doorway components

When framed in wood for snug fitting of a door, the doorway consists of two vertical jambs on either side, a lintel or head jamb at the top, and perhaps a threshold at the bottom. When a door has more than one movable section, one of the sections may be called a leaf. See door furniture for a discussion of attachments to doors such as door handles, doorknobs, and door knockers.

• Lintel – A horizontal beam above a door that supports the wall above it. (Also known as a header)
• Jambs – The vertical posts that form the sides of a door frame, where the hinges are mounted, and with which the bolt interacts.
• Sill (for exterior doors) – A horizontal sill plate below the door that supports the door frame. Similar to a Window Sill but for a door
• Threshold (for exterior doors) – A horizontal plate below the door that bridges the crack between the interior floor and the sill.
• Doorstop – a thin slat built inside the frame to prevent a door from swinging through when closed, an act which might break the hinges.
• Architrave – The decorative molding that outlines a door frame. (called an Archivolt if the door is arched). Called door casing or brickmold in North America.

Related hardware

Door furniture or hardware refers to any of the items that are attached to a door or a drawer to enhance its functionality or appearance. This includes items such as hinges, handles, door stops, etc.

Related accidents

Door safety relates to prevention of door-related accidents. Such accidents take place in various forms, and in a number of locations; ranging from car doors to garage doors. Accidents vary in severity and frequency. According to the National Safety Council in the United States, 300,000 injuries are caused by doors every year.^[21]

The types of accidents vary from relatively minor cases where doors cause damage to other objects, such as walls, to serious cases resulting in human injury, particularly to fingers, hands, and feet. A closing door can exert up to 40 tons per square inch of pressure between the hinges. Because of the number of accidents taking place, there has been a surge in the number of lawsuits. Thus organisations may be at risk when car doors or doors within buildings are unprotected.

According to the US General Services Administration:

"...It is essential that children's fingers be protected from being crushed or otherwise injured in the hinge space of a swinging door or gate. There are simple devices available to attach to the hinge side, ensuring that this type of injury does not occur. As the door closes, the hand is pushed out of the opening, away from harm. In addition, young children are vulnerable to injury when they fall against the other (hinged) side of doors and gates, striking projected hinges. Piano hinges are not recommended to alleviate this problem as they tend to sag over time with heavy use. Instead, an inexpensive device fitting over hinges is available on the market and should be used to ensure safety..."^[22]

Outward and inward opening

Whenever a door is opened outwards there is a risk that it could strike another person. In many cases this can be avoided by architectural design which favors doors which open inwards into rooms (from the perspective of a common area such as a corridor, the door opens outwards). In cases where this is infeasible, it may be possible to avoid an accident by placing windows in the door.^[23]

However, inward-hinged doors can also escalate an accident by preventing people from escaping the building: people inside the building may press against the doors, and thus prevent the doors from opening. This was partly the case in the Grue Church fire in Norway in 1822.

Today, the exterior doors of most large (especially public) buildings open outward, while interior doors such as doors to individual rooms, offices, suites, etc. open inward, as do many exterior doors of houses, particularly in North America.

Doorstops

Doorstops are simple devices used to prevent a door from coming into contact with another object (typically a wall). Without the door stop damage might be done to the wall. They may either absorb the force of a moving door, or hold the door in place to prevent unintended motion.

Door guards

The purpose of door guards (also known as hinge guards, anti-finger trapping devices, or finger guards) is to reduce the number of finger trapping accidents in doors, as doors pose a risk to children especially when closing. Door guards protect fingers in door hinges by covering the gap that is created by opening doors by covering the hinges of doors with a piece of rubber or plastic that wraps from the door frame to the door. There are also door safety products which eject the fingers from the push side of the door as it is being closed.

There are various levels of door protection. Front door protection a front anti-finger trapping device but leaves the rear hinge pin side of the door unprotected. Full door protection uses front and rear anti-finger trapping devices and ensures the hinge side of a door is fully protected. Which level of protection is appropriate should be determined by a risk assessment of the door.

There is also handle-side door protection, which prevents the door from slamming shut on the frame, which can cause injury to fingers/hands.

Safety doors

A safety door prevents finger injuries near the hinges without the use of door guards. Rather than cover the danger area, the approach is to change the shape of the door so that an accessible gap does not form in the first place. This is achieved by adding a perfectly circular ("bull-nose" shaped) extension to the door, which moves in and out of a cavity as the door opens and closes. This prevents any part of a hand being crushed near the hinges – either inside or outside. These doors have an operating range of slightly over 90 degrees, so their use is limited to where they come into contact with a side wall when fully open (or where they can be prevented from opening too far by a doorstop).

Glass doors

Glass doors pose the risk of unintentional collision if a person believes the door to be open when it is closed, or is unaware there is a door at all. This risk may be particularly pronounced with sliding glass doors because they often have large single panes which are hard to see. To prevent injury from glass doors, stickers or other types of warnings are sometimes placed on the glass surface to make it more visible. For instance, in the UK, Regulation 14 of the Workplace (Health and Safety Regulations) 1992 requires the marking of windows and glass doors to make them conspicuous. Australian Standards: AS1288 and AS2208 require glass doors to be made from laminated or toughened glass.

Fire

Special purpose fire doors are often employed in buildings to reduce the overall risk of fire, particularly by preventing the spread of fire and smoke. In cases where they are improperly installed, employed, or tampered with, the risk of fire can be increased. Door closers are sometimes used to ensure fire doors remain closed.

An additional risk in a fire is that doors may prevent access to emergency services personnel in order to fight the fire, rescue occupants, etc. Door breaching techniques may be required in these situations to gain access.

Panic bars are often used in buildings so that a door locked from the exterior can quickly and easily be opened from the inside in the event of a fire or other emergency.

Vehicle doors

There may be an increased risk of trapping hands or fingers in car doors compared to other types of doors, due to the proximity in which the occupant sits. In some car accidents, injury to occupants from the movement of car doors may occur.

Bicyclists often fear collision with an opening car door in case the car's occupant does not look carefully to check that it is safe to open the door. Because cyclists often ride near parked cars along the side of the road (see door zone) they are particularly vulnerable.

Aircraft doors

Doors which lead from interior, pressurized, sections of an aircraft to exterior or unpressurized areas can pose extreme risk if they are inadvertently opened during flight. This can be mitigated by having doors that open inwardly and are designed to be forced into their door frames by the internal cabin pressure – most cabin doors are of this type. However, an outward opening door is often advantageous for cargo doors to maximise available space, and these need to be secured by hefty locking mechanisms to overcome internal pressure.

A number of accidents have occurred where outward-opening aircraft doors were opened in flight, often accidentally:

• American Airlines Flight 96 (1972)
• Turkish Airlines Flight 981 (1974)
• Pan Am Flight 125 (1987)
• United Airlines Flight 811 (1989)

See also

Notes

References

•  This article incorporates text from a publication now in the public domain: Spiers, Richard Phené (1911). "Door". In Chisholm, Hugh. Encyclopædia Britannica. 8 (11th ed.). Cambridge University Press. pp. 419–420. 

External links

• Media related to Doors at Wikimedia Commons