Polycarbonate is a thick plastic sometimes used in eyeglasses or bulletproof windows. A polycarbonate greenhouse uses this material for the roof and walls, but may have a frame made of steel or aluminum. There may be bars along the top for hanging baskets, and shelves on all sides for planters. These greenhouses can be rounded or curved at the top, and other models have slanted roofs. There can also be an aluminum door with glass or screen panels.
The frame of a polycarbonate greenhouse is typically constructed of aluminum or steel. The eaves, which are the lower edges of the roof, and rafters may also be metal. Polycarbonate panels are usually placed on top of the frame both on the roof and along the outer walls. This means the greenhouse is completely transparent, in most instances.
The polycarbonate walls may contain anywhere from one to five panels. Each panel can be approximately .11 inches (3 mm) thick. Greenhouses with five-panel walls are generally more energy efficient, but cost more than those with single or dual walls.
Many polycarbonate greenhouse models have additional features. Some models have shelves along the side to place potted plants. Others have hooks or beams suspended from the ceiling for hanging baskets. Some may have roof vents that automatically open and close whenever the temperature fluctuates. They may also have entry doors that lock when they are not being used.
This building comes in a number of different sizes. A small polycarbonate greenhouse intended for residential use might be around six feet (1.83 m) long and wide while a larger one could be up to 51 feet (15.55 m) long and 20 feet (6.1 m) wide. Commercial structures might be even bigger, and these greenhouses can also be custom-designed. City dwellers may also choose a miniature one that somewhat resembles a baker's rack and is designed to be placed on a porch or patio.
The advantages of a polycarbonate greenhouse are energy efficiency, lower cost, and aesthetics. The energy efficiency often leads to an increased growing season. Polycarbonate is also less likely than glass to break should a rock or hailstone hit it.
One of the disadvantages of a polycarbonate greenhouse is that it needs to be cleaned often. This is because the walls attract dust and dirt, which may reduce the amount of light entering the greenhouse. Condensation can also build up between the panels of the structure, allowing harmful algae to grow.