How to Measure How Much Plastic Is on a Greenhouse

Greenhouses used for plant production in areas with cool climates allow sunlight penetration through the use of either glass or plastic (polyurethane).

Calculate the surface area of plastic sheeting used to enclose a greenhouse.Calculate the surface area of plastic sheeting used to enclose a greenhouse.
Most simple greenhouses are shaped like a traditional house; some have a rounded roof. Determining how much plastic is needed, or currently covers, the structure is a simple arithmetic task, using surface-area formulations and addition. Keep in mind that some plastic-covered structures employ more than one layer of plastic to increase insulation values.

Measure each side or roof panel of the greenhouse structure with a tape measure. Whichever increment you use, whether feet or yards, remain consistent with it, to obtain accurate surface area across the entire structure.

Visualize each side or roof of the greenhouse as a simple geometric shape, such as a square or rectangle. Multiple each shape (surface)'s height by its weight to obtain the surface area covered by plastic, for that particular surface.

Jot down the measurements of all the surfaces, and add them up. For clarity, draw each plastic-covered shape (wall or roof) on the paper and write the corresponding measurement next to it. This ensures all surfaces are counted.

Approximate the surface area of tube-like greenhouses (those with a curved roof) covered in plastic by measuring the overall length of the structure as well as the width. The width measurement must take into account the curved roof line. Use a ladder and bendable tape measure to accurately determine the actual dimension of the curved roof, which is the width dimension. Multiply the width by the length to yield the tubular structure's total plastic-covered surface area.

Things You Will Need

  • Tape measure
  • Calculator
  • A-frame ladder


  • Once you know the surface area covered in plastic for a greenhouse, use that number to determine what size plastic rolls (dimensions available for purchase) most efficiently cover the structure's area with the fewest amount of seams. Seams in the plastic covering are weak, giving air, wind and water an opportunity to move in and out of the greenhouse structure.

About the Author

Jacob J. Wright became a full-time writer in 2008, with articles appearing on various websites. He has worked professionally at gardens in Colorado, Florida, Minnesota, New York, North Carolina and Pennsylvania. Wright holds a graduate diploma in environmental horticulture from the University of Melbourne, Australia, and a Master of Science in public horticulture from the University of Delaware.