The most popular framing material for greenhouse kits is aluminum. Compared to other framing materials, an aluminum greenhouse can be easy to put together, is considered very durable and lightweight, and comes in a wide variety of style and color options. The cons of an aluminum greenhouse include the lack of insulation, the difficulty of expanding an existing greenhouse, the softness of the metal, and the very high cost.
Aluminum is so popular in ready-to-assemble greenhouse kits because it is lightweight and easily packaged. An aluminum greenhouse kit will usually come with nearly everything needed to set up the greenhouse, making this type of greenhouse exceptionally easy to put together. The styles and colors available for an aluminum greenhouse kit are virtually limitless as it is easy to paint aluminum, and the slim profile of the framing will allow the greenhouse to blend nicely with landscaping.
One thing that does not come with an aluminum greenhouse kit, however, is a sturdy base. In areas with moderate-to-strong winds, an aluminum greenhouse will need to have a very heavy, solid foundation in order to maintain stability, making the structure permanent and not portable. Aluminum is also a very soft metal, which means that heavy snows and wind can cause the frame to bend and twist. Compared to other metals like steel or wood, aluminum is considered more durable because it will not rust or rot and is not worn down by the sun. Maintenance is very minimal and aluminum will not need to be repaired or replaced over time.
Insulation is a problem with aluminum greenhouse because it does not retain heat or keep out cold, as is necessary for a greenhouse. Condensation can also be a problem inside an aluminum greenhouse, which can promote bacterial growth and mold. Other forms of insulation are necessary to maintain the appropriate temperature in an aluminum greenhouse in very cold weather.
The cost of producing aluminum for greenhouses is very high because it is a composite material, making it one of the most expensive metals on the market. In order to build a sturdy, permanent aluminum greenhouse, it might be necessary to use more framing than is used in wooden or steel greenhouses, substantially adding to the cost. This can be a serious disadvantage to building an aluminum greenhouse if cost is an issue. Additionally, it can be very difficult to expand an existing structure because of the thinness of the frames and high cost of materials.