Greenhouse Structures and Systems – Planning

When you are planning the building of your greenhouse one of the first things you need to do is to decide on the materials you are going to use.

Framing Options
The structural materials you use for the frame should be durable and strong. Options include:

Aluminum

- This is an inexpensive, lightweight yet strong option. The drawback is the aluminum lets heat out of the greenhouse.

Wood

- Framing with wood provides strength and allows less heat loss than aluminum. However, it takes up more space and therefore allows less light in. Also, wood framing requires more upkeep to prevent rot.

Recycled materials

- This is a low cost option, but may be in limited supply.

Lighting Options

Plants in greenhouses require lots of light. Placing the greenhouse in a sunny location is the best way to ensure that your plants get enough light. Make sure that it is not obstructed by large trees or in the shade of your house. In addition, the orientation of the greenhouse and the placement of glazing can influence the amount of light that gets through. The glazing needs to be at the correct angle for the sun’s path, allowing more light to be passed through and less to be reflected away. The type of glazing you choose will also impact how much light gets through.

Glazing Options

There are several types of glazing you can choose and each will affect your greenhouse in several ways.
Single-pane glass allows the maximum amount of light to pass through. However, this type of glass is expensive, heavy, and easily breakable. In addition, some local building codes require safety glass. Other glazing option include:

• Acrylic panels
• Polycarbonate panels
• Polyethylene sheeting
• Fiberglass sheeting
• Corrugated fiberglass sheeting

Each of these options offer advantages and disadvantages in terms of light, cost, durability, and installation.

Heating Options

Depending upon what you are intending to grow, your greenhouse can be either heated or unheated. If you live in a northern climate, then an unheated greenhouse can be used to extend your growing season but will not allow you to grow plants and vegetables year-round. If you want year-round produce or wish to grow tropical plants, citrus fruits, or orchids, then you will need to plan on heating your greenhouse. On average, in an unheated greenhouse the temperature remains about 10 degrees higher at night than the outside temperature. So, you would be able to grow plants about one hardiness zone warmer than you live in. On a sunny day temperatures inside the greenhouse are much warmer than outside, perhaps up to 50 degrees warmer. Heating costs can vary widely depending upon the location, size of greenhouse, and materials used to construct.

These are some of the structural issues you need to keep in mind when you are planning build a greenhouse.