Who issues coastal permits for ADUs in Seal Beach?
The California Coastal Commission. As of October 2026, Seal Beach does not have a certified Local Coastal Program, according to a 2025 Coastal Commission staff report. That makes the Commission the permit-issuing agency for development in the city's coastal zone, and the Coastal Act is the standard of review.
This is different from Long Beach, where the city itself issues an administrative coastal permit for ADUs. In Seal Beach, a coastal zone ADU means a separate application to the Commission alongside city plan review.
What has the Coastal Commission required on Seal Beach ADUs?
One example: in an October 2025 staff report on a 10th Street project with a new house, an attached ADU and a junior ADU, staff noted that state law did not require parking for the ADUs. To keep the units from working as a duplex, the conditions required separate utility meters for the house and the ADU, separate pedestrian access for each unit, and no later merging of the accessory units into the house.
Conditions are set case by case, so we read recent Commission decisions before designing near the water.
What about College Park East and other inland neighborhoods?
Seal Beach has inland neighborhoods too. In College Park East, the first homes were built in 1965, according to the local Sun newspaper, which also reported lots planned at 65 by 100 feet, with many homes on 55 by 100 foot lots. A lot that size can often fit a detached ADU with 4-foot side and rear setbacks, depending on where the house and garage sit.
We check whether your address is inside the coastal zone first, because that decides the permit path.
How do we build for the coast?
Close to the ocean, salt air is hard on exterior metal and finishes. On coastal lots we specify corrosion-resistant fasteners, flashing and exterior hardware, and choose windows and siding with that exposure in mind.
Does state ADU law apply in Seal Beach?
Yes, alongside the Coastal Act. As of October 2026, state ADU law means, for example, no replacement parking for a converted garage, no owner-occupancy requirement for an ADU, and junior ADUs of up to 500 sq ft. ADU rentals in Seal Beach must also meet state minimum rental terms; see our rental guide.
How long will a Seal Beach coastal ADU take?
It depends on whether your lot is in the coastal zone. Inland lots follow the city's ADU review. Coastal zone lots add a Commission permit; under state law, as of October 2026, the Commission must act on a complete ADU application within 60 days where a city has no certified program. We map your address against the coastal zone before anything else.
Related
As of October 2026. Sources: California Coastal Commission staff report Th9a (October 2025), California Government Code §66329, Seal Beach Sun (College Park East history, 2010).
See what fits on your Seal Beach lot
Send your address. We check whether you are in the coastal zone and which permits you need.