What type of greenhouse framework is characterized by a simple post and rafter design?

The post and rafter greenhouse framework is defined by its straightforward construction, where vertical posts support horizontal rafters. This design provides a stable and robust structure, making it suitable for various climate conditions. The simplicity of this design allows for ease of assembly, cost-effectiveness, and adaptability in size, which is beneficial for both commercial and hobbyist gardeners looking to create an efficient growing environment.

In contrast to the other options, an arch frame greenhouse utilizes curved structures for support, which provides excellent wind resistance but differs from the post and rafter method. A tunnel greenhouse, also known as a hoop house, has a rounded top created by a series of arches, specifically designed for maximizing sunlight and protecting plants but lacking the vertical posts typical in a post and rafter design. Meanwhile, a gable greenhouse features a peaked roof structure, resembling a conventional building roof, which adds complexity beyond a simple post and rafter framework. Each alternative structure serves unique purposes but does not embody the specific simplicity inherent in a post and rafter design.