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Plastic Lumber Installation Considerations

Expansion and Contraction A little innovation and creativity in engineering lets you apply recycled plastic lumber to the areas of your business or industry that require a product with increased durability and strength. Following are a few tips to help control and decrease the effects of expansion and contraction. Plastic lumber must be gapped end-to-end, based on the length of the board and temperature at installation. This will allow for the expansion of the material in warmer temperatures and the contraction of the material in cooler temperatures. You can expect that a 12ft board will expand 1/8” on each end when installed at 60°F based on an expected increase of 40°F. Therefore, in this example, you would gap the boards ¼” in end-to-end installation. To calculate expansion, multiply the number of inches of the board by the change in temperature in degrees Fahrenheit by the decimal .000045. Example: 192” x 100° x .000045 = .86” In the example above, you see that a 16ft board will change 7/8” in length from the cold of winter to the heat of summer. That is just under ½” on each end and too far for a screw to bend. Plan your gaps according to the temperature when laying the board and your climate fluctuations. Properly installed deck systems include hidden gaps and clips to allow for this expansion and contraction. Installers are responsible for installing the materials in a manner that accounts for this natural expansion and contraction. In very hot or very…