How much does it cost to power wash a 20×20 deck?

How much does it cost to power wash a 20×20 deck?

A 20×20 deck, covering 400 square feet, typically costs $150–$300 to professionally power wash, landing around $0.35–$0.75 per square foot depending on the wood or composite type and how much buildup has accumulated. Wood decks with heavy mildew or algae staining tend toward the higher end due to added scrubbing and dwell time for the cleaning solution, while composite decks in good condition, which often only need soap-and-water cleaning or gentle low-pressure washing, may fall toward the lower end. Many companies apply a minimum service fee of $100–$150 regardless of size, so a smaller deck like this may be priced closer to that minimum rather than strictly by square footage. Getting a specific quote after a walkthrough remains more accurate than square-footage math alone.