Expect to spend around $10,000 to $11,000 to replace a 20-by-20-foot deck. Using high-end materials like composite or exotic hardwoods can drive up the cost, as can custom features and design elements. You can also expect to pay more than average if your deck replacement requires a site evaluation or if you need the work done during the busy season.

The best way to clean your decking is to clear debris from the gaps between the boards, sweep the surface, rinse it, apply cleaner, rinse again, and let it dry fully. A homemade deck cleaner made of two gallons of warm water and 1/2 cup vinegar is a simple cleaning solution for both wood and composite decking. You can sprinkle baking soda on any spots with mold or mildew, then scrub the area and rinse clean. 

To flatten a cupped deck board, start by ensuring it’s dry. Then, try flipping the board over so the cupped side faces down and reattach it. If that’s not possible, you can use screws to pull it tighter to the joists or plane the edges slightly to reduce the cup. It’s best to replace severely cupped boards.

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.