With the framing completed, the next task was choosing and installing the plastic covering. I say choosing because not all types of plastic covering are the same. I used six mil UV-treated plastic designed only for greenhouse covering. This plastic covering is not the same type you buy at the big box stores. The rolls of plastic sold at the big box stores are not UV-treated. UV-treated plastic lasts longer when exposed to direct sunlight than regular plastic.

The greenhouse end walls were covered with plastic first. I used pressure treated wood strips and staples to secure the plastic to the existing wooden framing members. The outside temperature governed how tightly I attached the plastic. A cooler temperature needed a tighter plastic, because as the temperature rises, the plastic would expand and sag more.

The next task was to cover the main section of the greenhouse with plastic. This sheet needed to be large enough to hang over the sides by at least 2 to 4 feet. The sheet ends that overhung the sides were then attached to the side wall framing members using pressure treated wood strips. The sheet ends that ran along the sides of the greenhouse were attached to the bottom of the greenhouse base using wood strips. In this picture, the plastic covering has been completed. The front door has been installed along with a ventilation fan.