If you’re preparing to build a greenhouse, you’ve probably heard a lot about polycarbonate, as this material has become increasingly popular for greenhouse construction. To help ensure greenhouse builders aren’t mislead by common misconceptions about polycarbonate, we’ve rounded up a few of the most popular bits of misinformation and added the real facts, so you can make an informed decision for your greenhouse project. Here’s what you need to know.
False: Polycarbonate does not last long.
TRUE: Most polycarbonate comes with a 10 year warranty for multiwall sheets (and a 15 year warranty for solid sheets) and will last well beyond the warranty if it’s installed properly and cared for according to the manufacturer’s instructions.
False: Polycarbonate is difficult to cut, and it easily breaks, chips, and cracks.
TRUE: Polycarbonate can be easily cut using common tools, such as table saws, jig saws, and hand saws with fine-toothed blades. Chipping and cracking are more common with acrylic material, and acrylic requires greater care when cutting and drilling.
False: Polycarbonate sheets can be stored on site in direct sunlight during construction.
TRUE: Polycarbonate sheets have a protective film over their surface to shield them from scratching and damage during installation. Sheets with this protective film still intact should never be placed in direct sunlight, as the heat from the sun will bake the protective film onto the sheet, making removal virtually impossible without causing severe damage.
False: Polycarbonate can be bent into any shape without breaking.
TRUE: This material can be bent or “cold formed” at room temperature, but bending has its limits. Check the manufacturer’s instructions for the specific structure and thickness of product you’re using before attempting to bend or shape it.
False: Multiwall sheets can be installed horizontally or vertically.
TRUE: Multiwall polycarbonate has an internal structure that creates channels between the layers of material. These channels must always be installed vertically to ensure that any condensation that forms inside the channels drains properly. Failure to install sheets vertically may lead to moisture buildup, potential mold growth, and a generally cloudy appearance of the material.
False: Multiwall polycarbonate does not provide enough light transmission to support plant growth in a greenhouse.
TRUE: A 2-wall, 4mm thick, clear polycarbonate panel provides 82 percent light transmission, which is well within the 80 to 90 percent range required for greenhouse growing. It also provides thermal insulation, and the degree of thermal insulation can be adjusted with different internal structures and thicknesses to achieve the desired R-value.