Dome

Author: Leandro Alegsa Creation date: November 13, 2022

A dome is a building or roof that usually looks like the upper half of a sphere.

As a roof feature, domes make many religious and government buildings stand out, because if someone is speaking to others inside or under a dome, the voice sounds louder. Also a dome makes it easier to identify an important building, for example a temple or a palace.

A large stadium with a roof over the playing field is often called a "dome". One example of that usage is the Metrodome.

St. Peter's basilica in Vatican City, with a dome, seen from outside.
The same dome, seen from inside
Golden dome above the mausoleum of Fatima Masumah in Qom
Gilded onion domes of the Cathedral of the Annunciation, Moscow Kremlin
Fiberglass dome cottage in Davis, California. This dome was built in 1972 and is part of the Baggin's End student housing cooperative.
The dome of the United States Capitol in Washington, D.C.

The late antique pendentive dome of the Hagia Sophia was finished in 537 and set standards for centuries.

The bulging dome of the Taj Mahal can be derived from Persian models, Agra

Tambour dome at St. Nikolai at the Old Market, Potsdam

Designs

In addition to the cross-section, the relationship between the (imaginary) ground plan of the dome, the "base circle", and the ground plan of the room also determines the shape of a dome. Domes over a rectangular room must either be trimmed or supplemented.

The most common form is the dome in the shape of a hemisphere. Later (often segmented) domes are often bulged and usually two-shelled.
"Umbrella domes" are segmented domes with ridges or ribs.
When the base circle of the dome touches the corners of the floor plan, the shell is cut vertically by the walls. This form is called "hanging dome".
If the base circle lies further outside the ground plan, a "calotte dome" or "flat dome" is created, which as a spherical calotte is flatter than a hanging dome. Over a square ground plan, it results in a "Bohemian cap", also called "Stutzkuppel" or "Platzlgewölbe".
If the base circle of the dome is inscribed in the ground plan (the walls as tangents), an incomplete pendentive dome is placed between the walls and the actual dome, which is trimmed horizontally and on the cut edge of which the vault rests. The four segments of the "auxiliary dome" are called pendentif, the dome form thereafter "pendentif dome".
Between the pendentifs and the dome there is often a tambour, a cylindrical element that raises the dome and is often pierced with windows. The tambour, as well as the adjoining dome, can also take on an octagonal outline.
Instead of pendentifs, trumpets and (especially in Turkish and Indian architecture) "Turkish triangles" occur with the same function, filling the corners not with spherical but with conical segments or pyramids.
A "folding dome" is a dome with an outwardly curved surface that appears to be folded.

The statics of these designs are comparable to those of cross vaults, but more complex, as the lateral pressure does not act on the corners alone.

Suspension dome

Pendentive dome

Pendentif dome with tambour

Exposure

The illumination of the dome itself or the space below it was either through the opaion ("eye"), an opening at the apex, which since the Middle Ages has often been covered by a windowed lantern, or through openings in the lower part of the shell (e.g. Hagia Sophia). Later, a windowed tambour was often interposed, making the dome appear to float.

Search by letter

Languages