Greenhouse manufacturers offer a range of styles, which you can categorize into detached, ridge and furrow (gutter-connected), and lean-to. The latter is the most popular among hobbyists but not recommended for commercial greenhouses as the size of a lean-to greenhouse is limited.
As the name suggests, detached greenhouses are built independently. However, a corridor may connect the work areas between structures. The Quonset is one of the most common types of detached greenhouse, which often has arched rafters and typically has solid end walls to provide more support for the structure. Quonset greenhouses are suitable for most crops, although the growing area near the side walls is restricted.
A typical gutter connects ridge and furrow greenhouses at the eave and can be curved or gabled. Gabled greenhouses can have fiberglass or glass coverings. On the other hand, a curved arch is usually covered with lighter materials like polycarbonates or polyethylene.
Structural components of greenhouses
- Rafters. These are the greenhouse’s primary vertical support. They are commonly placed on 2-, 3-, or 4-foot centers, depending on the required strength of the structure. Depending on the width of the design, rafters could either be curved arch or truss type. If your greenhouse is more than 50 feet wide, it will need reinforced trusses.
- Purlins. They are the horizontal supports that run from each rafter. They are typically spaced four to eight feet apart, according to the size of the structure. A cross tie, in some cases, may also connect the purlins. This type of connection provides additional support, beneficial in greenhouse locations where high winds frequently occur.
- Side columns and posts. These are the vertical supports often installed at the height of one to ten feet. The side columns and posts determine the size of the greenhouse’s production area. In addition, they determine the efficiency of the structure. You can install vents on these sidewalls to provide insulation and cooling.
Materials for the frame
Manufacturers use various materials to construct greenhouses, with wood, steel, and aluminum the most popular. By far, aluminum is the most long-lasting and economical. Likewise, it is available in various thicknesses and shapes. Aluminum can be used for side posts, rafters, and other greenhouse components.
Although wood can be used, it is not a common material you will find in commercial greenhouses. Wood is not suitable for moist environments and deteriorates quickly. Pressure-treated lumber, which is resistant to decay, releases fumes that are not good for plants.
Roof and wall coverings
Providing the best transmission of light is glass. However, glass is heavy, so the structural components it needs will be costlier. In addition, the initial investment and maintenance for glass coverings are likewise expensive.
Most commercial greenhouses today use fiberglass, which is highly durable, and the structural components needed for their construction are not extensive. However, fiberglass can break down over time because of the effects of UV rays.
Depending on the location, you can use double sheets of polyethylene film inflated with air. While economical, the film can only last for two years.
- Gable roof. A greenhouse with a gable roof is the most common. The structure allows maximum amounts of sunlight. At the same time, the greenhouse provides adequate space for growing plants. In addition, because the roof is high and the walls are straight, movement inside the greenhouse is more effortless. You can purchase a prefabricated greenhouse kit or buy the materials and build the structure yourself.
- A-frame greenhouse. The design of an A-frame greenhouse is similar to a gable roof. However, the walls are lower, and the roof slopes at a sharper angle. But an A-frame is easier to construct, and you can do it yourself for a backyard greenhouse. But with this design, movement within the greenhouse is restricted because the roof is lower, and the air circulation may not be sufficient.
- Hoop style. The greenhouse looks like a series of half hoops. There is more height near the siders with the shape, giving more space for the plants to grow taller. At the same time, there is more space to move. Providing ventilation is easier. However, snow can build up on top of the hoop greenhouses, so you should clear them immediately to prevent damage to the structure.
- Gothic arch. If you want something attractive and elegant, a Gothic arch greenhouse will be an excellent choice. It looks like a combination of hoop and A-frame but the upper half of the wall curves and meets at the center point. As a result, the interior is higher, providing better air circulation and better mobility. Moreover, the shape of the roof allows more light to pass through and prevents rainwater and snow build-up.
An experienced commercial greenhouse manufacturer can help you choose the right style, material, and covering that will help you maximize your greenhouse production.