Site preparation is stressed because a 1-inch elevation change in 100 feet is uncommon in building most greenhouses. Include the installation of utilities and the foundation when planning the grading and filling of the site. The site should have easy access to electricity and water, and adequate roadway access. Place drain tiles under the site if it is an unusually wet area. Use 1 to 2 inches of sand for the final grading if the surface material is rough.
Sand helps prevent rocks and small roots from puncturing the black film plastic in the float beds.
Lay out the corners of the greenhouse carefully to the correct dimensions, keeping the corners square. Use a transit to set ground stakes or strings to the same height. The foundation pipes must be in line, at the required height, and at the required spacing, as outlined in the manufacturer's specifications. Use a small fan to inflate the space between the two layers of film plastic on the roof. Because moisture reduces the amount of light able to enter the greenhouse, inflate the space between the plastic layers with the cooler, dryer outside air rather than the warm, moist inside air, which can cause condensation.