While you can use various materials like sand or even just soil, gravel is widely considered the best option to put under a deck. It provides excellent drainage and is resistant to water, fire, and pests. Gravel also helps anchor the soil to prevent erosion during heavy rain and acts as a built-in weed blocker, reducing regular upkeep. Furthermore, it is simple to spread, available in various textures and tones, and adds a polished look that complements any deck design.

It depends on the type of wood. The average cost to build a deck out of pressure-treated lumber is $15 to $25 per square foot, but more affordable varieties such as bamboo and cedar cost less at around $3 to $10 per square foot. However, when comparing the cost of vinyl decking versus wood decking, it’s important to also consider ongoing maintenance costs. For example, most woods require regular sealing to keep them protected against weather and rot.

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.

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.