Yes, it is possible to add an under-deck drainage system to an existing deck by retrofitting it to the structure. This process may require some prep work. For example, many drainage systems are installed on top of the deck joists, which would require you to remove the decking boards and railings first. To avoid this, you could opt for a below-the-joist drainage system. For best results and to ensure proper installation, it is recommended to consult a professional. A pro can inspect your deck, make any necessary repairs, and then install the drainage system correctly.

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.

PVC decking can get slippery when wet because it’s made from plastic. However, composite and wood decking can also be slippery when wet. It’s best to wear shoes with grippy soles when walking on a wet deck, no matter the material, and to be extra cautious not to slip and fall down.

The average cost to professionally clean or pressure wash a deck is around $150, with prices typically ranging from $100 to $600. Several factors influence the final price, including the deck's size, material, condition, and how long it has been since its last cleaning. For a smaller deck of about 300 square feet, you might pay around $100. For a larger deck of 1,000 square feet or more, the cost could be closer to $300 to $400. Decks that are very dirty or haven't been cleaned in years may require more time and special detergents, which will increase the price. The deck's material also plays a role. Wood decks often cost more to clean because they require a gentle power washing technique to avoid damage. Composite decks are typically less expensive to clean, and cleaning a metal deck may cost around $100.