Decks & Patios: Real 2026 Costs, Materials & Process

Decks and patios in 2026: real costs across major US metros

A new deck or patio is the single best dollar-per-square-foot expansion of livable space. A 400-square-foot deck adds the equivalent of a small living room to your home for $20,000 to $35,000, far less than indoor square footage. The ROI at resale runs 60 to 75 percent for composite decks, higher in markets where outdoor entertaining matters (most of California, increasingly Seattle).

Covered vs open

major metro homeowners often build open decks to maximize sun. high-cost metros homeowners overwhelmingly favor covered decks (louvered pergola, solid roof) to make the space usable through the gray months. A louvered pergola adds $8,000 to $20,000 depending on size and motorization. A solid roof with insulation adds $15,000 to $40,000.

A 400-square-foot deck adds the equivalent of a small living room to your home for $20,000 to $35,000, far less than indoor square footage.

Permits and code essentials

Decks above 30 inches off grade, attached to the home, or above 200 square feet typically need permits. Code requires footings below frost line (deeper in WA than CA), ledger board flashing to prevent water intrusion at the house connection, and engineered hardware (joist hangers, lateral load brackets) per IRC R507.

The most common code mistake on DIY and unlicensed deck builds is improper ledger attachment. Ledgers must bolt through the rim joist of the house, never just the siding, with flashing tape behind and metal flashing on top. Check this before signing off on substantial completion.