There are approximately 5.33 board feet in a 2x4. You can use the board foot calculator in this article to easily find the answer. A 2x4 is 2 inches of thickness by 4 inches of width, so you need to find the length, with 8 feet being the most common. You’d use the calculator here to multiply 2 times 4 times 8, and then divide by 12, arriving at a total of 5.33 board feet. 

Deck boards should be spaced no more than three-eighths of an inch apart. This is enough space to allow water and small debris to pass through without collecting on the surface, but not enough to create a tripping hazard. Certain materials, like pressure-treated wood, shrink over time, so they may need less space at installation.

Many composite decking manufacturers, including the popular Trex brand, offer warranties that protect against warping under specific conditions. These warranties typically last between 20 and 50 years, but they usually exclude claims related to improper installation of the product. Some manufacturer warranties only cover decks built by certified professionals.

Coping is the material that lines the perimeter of a pool and seals the transition between the top of the pool wall and the water. Decking surrounds the poolscape and extends far beyond the water's edge to provide a safe walking and lounging area. In short, coping is the border between the decking and the pool itself.