Horticulture Principles and Practices

located on the south side of the building to take advantage of sunlight. Where more space
exists, the even-span style (see later section) may be adopted. A lean-to greenhouse may
also be window mounted.
Detached Greenhouses
As the name implies, detached greenhouses are designed to be freestanding and thus are
sometimes called by that name. None of the walls or the roof are attached to a preexisting
structure. A detached greenhouse can thus be located such that it takes maximum advantage
of environmental factors such as light and wind. Environmental regulation is easier in
detached than in lean-to styles. The most common style of greenhouse is the freestanding
even-span greenhouse. Also called the A-frame, this style consists of a symmetrical roof.
The even-span, or A-frame design, is the most common design for a glass
greenhouse.An even-span design has a symmetrical roof whose slopes have equal pitch and
width. The American-style A-frame design has a larger roof surface area (Figure 12–3), and
the Dutch design has small gables and a smaller roof surface area (Figure 12–4).
Another detached greenhouse style is the uneven-span design (Figure 12–5). This
design has asymmetrical roof slopes of unequal pitch and width. While it is adaptable to
hillsides or slopes, it does not readily lend itself to modern greenhouse automation and
as such is not commonly used.
Greenhouse roofs may be arched, as in the Quonset design (Figure 12–6) or the Gothic
arch design (Figure 12–7). The former design is quite commonly used, while the latter is not.
FIGURE 12–3
greenhouse.
A freestanding even-span American design
FIGURE 12–4 A freestanding even-span
Dutch design greenhouse.
Hill
FIGURE 12–5 An uneven-span greenhouse design. FIGURE 12–6 A Quonset greenhouse design. (Source: George
392 Chapter 12 Controlled-Environment Horticulture
Acquaah)