The problems with composite decking include a high rate of expansion and contraction from temperature swings. This characteristic can cause boards to split, delaminate, or peel. In addition, significant movement can cause shrinking, warping, twisting, and bending. For this reason, you should minimize moisture and ensure proper airflow below your deck.

Most building codes require that railing spindles (also known as balusters) on decks or stairs be spaced no more than four inches apart. This safety standard is often called the '4-inch sphere rule,' which means a sphere with a 4-inch diameter should not be able to pass through the opening between balusters. This rule is in place to prevent small children and pets from slipping through the railing. For the same reason, the space between the bottom rail and the deck or floor surface should also be no more than four inches. As a general guideline, professionals often install three balusters per foot of railing. However, since specific requirements can vary by location, it is essential to check your local building codes to ensure compliance before starting your project.

You can nail or screw composite decking, but 3-inch decking screws are the better fastener choice. Unlike nails, decking screws won’t back out of the composite material over time. There’s also little danger of splitting composite material when driving screws, so you don’t need to pre-drill holes unless otherwise recommended by your decking manufacturer.

Staining and sealing the underside of a deck creates a moisture barrier but traps water in the boards, quickly leading to rot. No matter how well you seal the above deck, water still gets through via nails and screw heads on the surface. Allow this water to flow naturally under the deck, where it is routed through the drainage system.