Hillside lots
Ridges and canyons around Happy Valley, Reliez Valley and the Burton Valley edges mean raised decks with tall posts, stepped footings and long stair runs. Expect plan check to look closely at footings near slopes, and budget for access on narrow, steep driveways. Details: hillside and elevated decks.
Fire hazard zones in Lafayette
The City's fire hazard map page lists about 41 acres Very High, 5,309 acres High and 1,668 acres Moderate under the 2025 maps, and notes that wildland-urban interface building rules apply in High and Very High zones (City of Lafayette). That's a much larger High footprint than many residents expect. If your lot is mapped, ask how the 10-foot decking rule applies to your project before choosing boards. Fire-resistant decking.
Who issues the permit
Lafayette handles planning and zoning, and contracts with Contra Costa County for building plan check and inspection (Lafayette building permits). Footing, framing and final inspections follow County procedures. Walnut Creek's small-deck exemption doesn't carry over; ask about Lafayette's. Deck permits.
Protected trees near footings
Lafayette protects native trees from 12 in diameter and riparian trees from 6 in (tree permit rules). Footings dug inside a protected oak's root zone can need a tree permit or an arborist's guidance, so locate footings around the trees early in design.
Moraga
Next door, Moraga's housing is a bit newer (median build year around 1972). The Town handles planning, Contra Costa County does building plan check and inspection, and the Moraga-Orinda Fire District covers fire rules. Moraga also has Very High areas on the 2025 maps.
Budgeting? Start with the deck cost guide.