Line It Up

• When installing a synthetic deck, it's vital to make sure the decking planks you use are the correct size for the deck you're planning to build, notes ThisOldHouse.com. Be sure to confirm sizes with a measuring tape before you cut the first plank. A power miter saw is recommended for this job because it can make accurate 90-degree crosscuts--the most common cut--and is safer than many other cutters because of its built-in blade guards. When slipping the first synthetic plank under any existing metal flashing--often the most challenging part of the project--it's critical that the first plank is parallel with the outer edge of the deck. Otherwise, you'll be building your deck on an angle. Use composite decking screws to help to fasten this deck board along the edge closest to the house at each joist. These screws are designed with reverse threads to remove composite material as the screw is driven, thus allowing it to seat well and preventing mushrooming (the creation of a raised bump in the material), according to Decks.com.
  
  

Smooth and Space It Out

• Hidden deck fasteners go in each joist along the edge of the deck board as well. Hidden deck fasteners make the surface of a deck smooth and safe by ensuring no nails or screws pop up, according to EB-TY. These fasteners come with sharpened spikes that you can drive into the plank using a hammer and plastic tapping block. A screw also goes through each hidden fastener and into the joists. The remainder of the planks of the synthetic deck also will use these sharpened spikes. In addition, ensuring adequate space between each plank during the installation process is important because composite material can expand and shrink as it heats and cools.
  
  

Notch and Straighten It Up

• Fabricating the outer end of the synthetic deck can be as tricky as installing the first plank. You must notch the the last plank to fit around the railing posts. It's also important that you trim the deck board to length at the very end of the project. To make a straight cut, screwing a straight-edged board to the deck as a circular saw guide is a recommended method. It's helpful to first use a chalk line to create the straight line at the appropriate length. A chalk line creates a crisp line in the blink of an eye, Jeff Gorton says in "How to Use a Chalk Line" for "Reader's Digest" magazine. It's like using an expensive laser--just simpler and cheaper.