Post 690 –by Gautam Shah
A door has some fundamental significance, Proportion (of Width vs Height aspects), Size (anthropometrics) and Scale (relative size to things around it). And all these imply different meaning on the exterior and interior faces. The door size, proportion and scale, relate to the architectural schema, fore-space and contours, interior of room, and functional passage requirements.
Doors have shutters, gates, frames, portals, surrounds, heads, thresholds, and other architectural adjuncts. These elements affect the form of the door. The doors could be really or perceptively narrow, wide, tall, short, small, large, thin or deep. But proportion is one character that remains consistent in all scales.
Most common set of proportions (Width : Height) have been: Two squares 1: 2, and Golden proportion 1:1.61. Other shapes include Square (Le Corbusier’s Ronchamp Doors), Horizontal Rectangle (Air hanger’s shutters). Sliding doors have a horizontal rectangle form. For twin shutters, each is of square shape. Multi panelled shutters have to maintain the horizontal bias for ease of movement. The real proportion of a door is seen when the shutter is open. A mid-pivot shutter may divide the opening in equal or unequal gaps. A door opening is more prominent if it is deep-set in the portal, or has contrasting colour+texture from its surround structure.
The vertical rectangular form makes the opening taller then its width. Small-width doors are technologically more efficient to construct and operate it ergonomically. Such narrow widths reduce the load on the hanging devices such as hinges and so are easy to open. Horizontal sliding doors, for easier movement, need to be wider then their height. Square doors are favourite with designers, but cannot be hung on side-end hinges. A square gap mislays its form when opened on mid or offset pivots. Very wide doors use vertical or horizontal pivots (garage doors) or sliding mechanisms (Japanese doors, Shop Rolling shutters).
Instead of a wide door, multiple (ganged) doors used at railway station are multiple units in a row. Similar effect occurs for multiple folding or stacking shutters for verandahs. Multiple doors and shutters provide spaced control for simultaneity, location, orientation. Where multiple tracks are not, feasible, shutters are joined together like the bellows of an accordion to form a sliding and folding stack. Folding or collapsible doors were first used in cabinets and cupboards, and diffuse the exchange over a wider zone.
A door is primarily sized for passage of humans, but often designed for mix of purposes. Some doors are exclusively for passage of goods and animals (hoppers, trap or flap doors), and so may not have any size relevance for human passage. Doors are functional elements of optimal size yet economics and technology govern its size and details. The critical aspect of door design is its width aspect. An insufficient width retards the speed, or even makes it difficult or impossible to transit through. But small width enforces discipline on chaotic traffic of entrants. Narrow width openings increase the integrity of the load-bearing structure. A very generous width fails to. Such wide openings need extra dividing barricades to channelize the traffic, or multiple narrower sub-gate systems. Bunker doors must be carefully small sized for increasing resistance to blast pressures.
Door portal size and the size of the shutter, are two different things. Doors of extra ordinarily large sizes or monumental proportions have been used through ages. A large door metaphorically denotes unrestricted transit, grand reception, fearlessness or power, affluence, and dominance. Technologically a door shutter cannot be very large, so doors placed in large portals and with adjunct structures.
As a social concern in modern times, it is essential to provide doors widths suitable for disabled persons, using walking stick, crutch walkers, a wheel chair, stretcher or assisted by others. Widths of doors for, toilet, elevators, closets, store rooms, change rooms, and such other lone user utilities are considered more critical for such users.
Some famous doors > Treasury of Atreus, Mycenae 9′-0” x 18′-0″, Parthenon, Rome 0′-0″ x 24′-2″, Erechtheion, Athens 8′-0″ x 17′-2″, S. Martin, Worms 5′-8″ x 11′-3″, Palazzo Pietro Massimi, Rome, main entrance door 6′-10″ x 13′-8″, National Archives in Washington, DC, Constitution Avenue bronze doors 37′-7″ x 10′ (and 11″thick), Vehicle Assembly Building VAB of NASA door height 456′.
Simple sliding doors allow variable and exact control over the width of opening. Automatic sliding doors such as for elevators and for entrances of public buildings open to width governed by the density and frequency of traffic. Revolving doors have optimum opening size to maintain the air lock and prevent anyone forcing a reverse movement. Folding shutter doors allow incremental width of the opening. Garage doors sliding up were devised to get a maximum width of opening.
Height of a door is checked for three parameters: the height available within the opening, the height of the door head, and the height of the threshold. The actual passage height of a door is affected by the level of terrain immediately inside and outside the door. Low level doors have been used to reduce the heat gain or loss (e.g. igloos), the storm water (e.g. sea front warehouses in America).
The scale of a door is governed by the architectural scheme, impinging built mass and the surrounding terrain. The scale of a door is also referential. Proportionately a door or gate opening seems smaller, if the adjacent wall or barrier system is very evident. On the same scale a large or multiple openings make barriers less effective. The exchange occurring across a small opening is very intense, compared to a large gateway.
Adjunct structures enhance the perceived scale and significance of the door. Fort gates and other gateways have not only very large doors but also have elaborate adjunct structures like portals, abutments, ramparts, bulwarks, bastions, Bastille, battlements, belvederes (Chhatri), buttress, campaniles (bell towers). Historically, very large (wide and tall) doors have been a necessity, for functional passage as well as for splendour. Doors are intentionally made smaller, if these are insignificant (backdoor, servant door, supply door), or need to be concealed, such as the secret or escape doors. Mid town gates are designed as multiple (three or five) openings to serve different levels of traffic. Doors are added with side and top lites, pediment, surrounds, free columns or half-pilasters to enhance the scale.
Egyptian temples had very tall openings, the lower section was shuttered and the upper section was a left over gap, which allowed entry of early morning Sun God Ra. Gothic churches had upper section of the door converted into a Rose window. Very tall doors, unless required for passage, are turned into transom lites. Very tall doors require a visual correction. Romans constructed tall doors with a wider base and narrower top. For very tall doors, the construction of strong shutter and relevant opening control mechanisms have been the greatest deterrent. Tall opening like effects are created with architectural door portals and alcoves where the functional door is very much smaller.
Low level doors have been used to reduce the heat gain or loss (e.g. igloos), the storm water seepage (e.g. sea front warehouses in America). Romans constructed tall doors that were wider at the base than at the top to correct the visual perspective.
Large door shutters require lateral stiffening, as the usual thin shutter leaf construction is insufficient against buckling forces such as the wind, blasts, and often sonic boom pressures. Aircraft hangers’ and spaceships’ assembly workshops (Apollo, Columbia, USA) have very large doors with additional lateral framing. Hanger doors are designed to be sliding from top, bottom or both. Similarly dams and canal gates have to resist not only the pressure of retained water but dynamic pressures of waves and eddy currents. Such doors are designed as 3D entities. Stadia and such public spaces where people are likely to push against the gates, extra lateral stability is required.