Half Moon Bay is the coastside’s anchor town — a former agricultural community along Highway 1 where the housing stock mixes old beach cottages, mid-century ranch homes, and newer coastal builds around a historic Main Street. Parcels vary widely: compact in-town lots near downtown, larger rural-agricultural properties along Highway 92 and the coastside roads, and hillside homes climbing toward the ridgelines. Fog, ocean air, and the coastal setting shape every construction decision, from materials to drainage.
On Half Moon Bay’s larger rural and semi-rural parcels, a detached ADU up to 1,200 square feet is often feasible — a true guest cottage or farmworker and family housing with room to breathe. In town, the more common paths are garage conversions, attached additions, and compact detached units sized to the lot. Converting an existing garage keeps the footprint unchanged and, under state law, generally cannot be burdened with replacement parking requirements — a meaningful advantage where coastal parking is already tight.
Junior ADUs (JADUs) suit Half Moon Bay’s older cottages well. Carving a compact, up-to-500-square-foot unit out of existing living space gives homeowners a low-cost entry point with no new foundation: a space for an aging parent, a caretaker, or a modest rental. State law prohibits cities from requiring owner-occupancy for standard ADUs, so most Half Moon Bay ADU projects can be rented to long-term tenants without the homeowner living on site.
Permitting in Half Moon Bay carries the one overlay that truly changes the process: much of the city sits in the coastal zone, so ADU projects typically route through both the city’s Community Development Department and the Coastal Commission’s coastal development permit framework. California’s ministerial (by-right) ADU approval still applies to the housing side, but the coastal permit adds a review layer with its own timeline — we confirm the coastal zone boundary for each parcel during feasibility and plan the submittal sequence accordingly. State law caps required side and rear setbacks at 4 feet, and some rural parcels carry septic systems that need evaluation before a second dwelling is designed.
Rental demand on the coastside is driven by the hospitality and agricultural economy, the Highway 92 commute to the Peninsula job centers, and a steady stream of people who simply want to live by the ocean. Half Moon Bay’s older cottages often need electrical panel upgrades and weather-hardened construction detailing, which we fold into the design. An ADU here should be built for the marine climate first and the rental market second — get the envelope right and the rest follows.
Ready to find out what your Half Moon Bay lot can carry? ADU Cities is a Southern California ADU design-build firm — we handle feasibility, design, permits, and construction under one roof. Call 562.810.1965 for a free consultation and site evaluation. CSLB #1138550.
