How to Measure How Much Plastic Is on a Greenhouse

Jacob J. Wright

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

Calculate the surface area of plastic sheeting used to enclose a greenhouse.
  1. 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.

  2. 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.

  3. 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.

  4. 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.