Before installing a deck, you must build a base for the deck to rest upon, often made of compacted soil or gravel. While gravel is an optional material, it helps with drainage. Some contractors also recommend installing a weed control membrane, which helps provide a solid foundation for the frame. In the case of an elevated deck, a pro will often lay down a concrete slab as a foundation. 

You do not have to dig footers for a deck as long as it meets local code and holds up to weather in your area. If you live somewhere that experiences high winds and earthquakes, you may need to dig for your deck posts. Deck blocks, post anchors with base plates, and helical pile systems are the three no-dig deck post options you can choose from if local code permits.

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.

Deck skirting shouldn’t touch the ground, especially if you have a wood deck, which is vulnerable to moisture. Ideally, you should leave at least 3/4 of an inch of space between the deck skirting and the ground for more ventilation. Pros also recommend that you incorporate about 1 square foot of space for ventilation for the underside of the deck to every 150 square feet of decking. Proper ventilation prevents mold growth and rot that can damage your deck.