If you’re like many California homeowners, you might be considering adding an ADU to your property. And if you’re lucky enough to live in a coastal zone, you have the added bonus of breathtaking ocean views and proximity to some of the state’s most desirable beaches. 

But before you start planning your dream addition, it’s important to understand the building restrictions in place to preserve the natural beauty and integrity of the coast. Even though California and the coast seem made for each other, take a closer look at all the reasons why construction in coastal areas near San Marcos often takes much longer – even with the help of experienced home addition architects.

How are ADU regulations different for coastal properties?

How can adverse effects be avoided

Unlike properties in inland areas that require approval from the local building department before building an ADU, coastal properties must comply with both LCP regulations and local zoning laws.

Coastal development authorities must obtain approval from the CCC to implement amended regulations. Additionally, CDPs for proposed ADUs that do not comply with LCP can’t be issued before CCC approves the amendment.

How can adverse effects be avoided? 

And what exactly are adverse effects? In addition to limiting public access to the scenery along the coast, ADUs could adversely affect coastal access paths, limiting coastal views, compromising slope stability, or harming coastal plants. These are the exact reasons why ADUs near water may result in larger setbacks. 

Still, keep in mind there are far greater obstacles to obtaining permits in the following areas:

  • Wet beach (shore far from the high tide mark)
  • Environmentally sensitive habitat or scenic areas
  • Vegetation-rich areas
  • Zones of extreme fire hazard severity
  • Areas in close proximity to a coastal stream or bluff
  • Areas with critical water supply shortages

Waivers and exemptions: how do they work?

Typically, ADUs that are converted from existing spaces such as garages or that share one or more walls with existing structures qualify as single-family homes. Building a standalone unit, however, usually involves a CDP unless there’s an approved waiver program.


Waivers and exemptions how do they work

In California’s coastal zones, improvements such as additions to existing single-family dwellings are often exempt from Coastal Act permitting requirements, unless they pose a risk of adverse environmental effects. This means that the construction or conversion of an ADU within or directly attached to an existing single-family residence usually qualifies as an exempt improvement. However, guest houses and detached residential units are not considered part of a single-family residence, so construction or improvements to them are not exempt improvement and may require additional permitting.


In some cases, if an ADU meets certain criteria, it may be eligible for a Coastal Development Permit (CDP) waiver. In cases where a waiver provision appears in the local coastal plan (LCP) and an ADU meets the criteria, the local government may waive the permit requirement. However, some LCPs do not allow for waivers, but may allow expedited approval procedures. If an LCP does not have provisions for CDP waivers or expedited approvals, the local government can submit an LCP amendment to the Coastal Commission. Without an existing waiver procedure, obtaining a permit for an ADU can involve more red tape, time, and money.

Where can I find skilled home addition architects in San Marcos?

Are you looking for a qualified contractor who can guide you through the process and ensure that your ADU meets all requirements? Or perhaps you’re looking to expand your home but don’t know where to begin? No worries, Lars Architecture got you covered. 

Through the years, we have completed a wide range of successful projects, ranging from stylish kitchens spaces, cozy guest bedrooms, and luxe primary suites, to expansive second-floor projects, and so much more. Feel free to contact us for more information on your upcoming project, whether it’s revamping a room for a new purpose or something completely different.