A Walled Patio, Open to the Sky:

Like a lanai, an atrium is part of the basic structure of a house. Traditionally, an atrium is located in the center of a house, is open to the sky, but enclosed on four sides by the house walls. Atriums have been in use in one form or another since ancient civilization. If a house is built on a small urban lot, an atrium can provide a private outdoor area that is completely shut off from the street and from neighbors.

On larger properties, atrium can be more intimate gardens within the house, as opposed to the larger, more open garden outdoors. In settings where most outdoor areas are exposed to wind, an atrium offers shelter. Perhaps most importantly -- if designed right, all the rooms of the house that face the atrium have glass walls and share the same light, air and garden view.

Most atriums are room sized, planned on an indoor rather than an outdoor scale. Landscaping should be chosen wisely -- it's preferable to use slow-growing, neat plants rather than fast-growing and leggy plants. Succulents or hardy houseplants are often perfect choices for an atrium garden.

While atriums have their roots in Roman architecture, they were often used in Mid-century modern designs, including many of the Case Study houses.