Atrium

Also called atria, atriums

In a Roman house, the central hall open to the sky through the compluvium, with the impluvium below. In an Early Christian church, the colonnaded forecourt in front of the narthex, often with a fountain.

See also: Compluvium, Impluvium, Narthex, Domus

Rules that use the word

From the atrium to the apse. Order the church as a single path: a colonnaded atrium, a narthex, the long nave drawn toward the altar, and the apse framed by a triumphal arch at the end of the axis.

Three proportions for the atrium. Give the atrium one of three shapes: width to length as 3 : 5, or 2 : 3, or a length equal to the diagonal of the square on the width; and make its height to the girders a quarter less than its width.

Alae, tablinum and fauces from the atrium. Proportion the rooms round the atrium from it: the alae from its length (a third for atria of 30–40 feet, a quarter for 50–60), the tablinum from its width (two-thirds for a 20-foot atrium, half for 30–40 feet, two-fifths for 40–60), and the entrance passage from the tablinum.

The opening in the roof. Leave an opening in the atrium roof not less than a quarter nor more than a third of the atrium’s width, with a length in proportion; beneath it set a basin to receive the rain.

Where it appears in the book

In the chapters Walls and Openings, The Classical World, Byzantium and the Early Church.

A feature of Early Christian architecture.

Nearby in the glossary

Arithmetic mean · Arris · Ashlar · Astragal · Attic · Attic base · Attractor · Avlu