Modern greenhouses are classified as Lean-to, Detached, or Ridge and Furrow, sometimes known as Gutter-connected structures. Lean-to greenhouses typically use one wall of an adjacent building for support, and are built as three-sided structures with a sloping clear or opaque roof. Detached greenhouses are stand-alone structures, commonly with two long sides and two shorter ends, and either a Quonset-style or gabled "roof." Ridge and Furrow greenhouses, sometimes known as Gutter-connected, can be two or more such structures connected along their long dimension, primarily used in large, commercial agricultural applications.
The defining characteristic of all greenhouses is that the roof and/or side walls are formed of clear, opaque or translucent material, normally glass, plexiglass or plastic film or sheeting that allows natural light to penetrate and warm the interior. However, greenhouses vary tremendously in size, purpose and use. The difference between Quonset-style and gabled structures is basically one of design only. Both are well-suited for their intended purpose.
