Accessory Dwelling Units (ADUs) have become an increasingly popular option for homeowners in San Diego, offering additional living space or rental income potential. But did you know that in certain scenarios, you can actually build an ADU taller than your primary dwelling unit?
Here’s a breakdown of how this is possible, thanks to San Diego’s municipal code.
Understanding the Angled Building Envelope Plane
The key to building a taller ADU lies in a specific regulation within San Diego’s municipal code: the angled building envelope plane, also known as the angled plane restriction or angled plane setback.
This regulation primarily applies to primary dwelling units and determines how high a structure can be built relative to its side yard setbacks.
In most residential zones, you start with a required side yard setback, typically between three and five feet. From that point, you can build upwards to a height of 24 feet (or 27 feet in RT zones).
However, once you reach this height, the angled plane restriction kicks in, requiring the building to follow an angle – usually 30 or 45 degrees – that limits its maximum height as it extends upwards.
On narrow lots, such as a 25-foot-wide property, this restriction often prevents primary dwelling units from reaching the maximum height allowed by the base zone (commonly 29 feet).
How ADUs Can Exceed Height Restrictions
Here’s where things get interesting: ADUs are not required to respect certain setbacks, including the angled plane restriction.
This means that an ADU can encroach into the angled plane and achieve greater height than the primary dwelling unit, particularly on narrower lots. Essentially, the flexibility in setbacks granted to ADUs allows them to exceed height limits that would otherwise apply to the main structure.
Important Considerations
While ADUs can bypass the angled plane restriction for side yard setbacks, they must still adhere to front yard setback requirements.
This means that the front yard angled plane restriction still applies to ADUs, so they cannot encroach into that area. It’s important to factor this into your design to avoid potential issues with compliance.
Ready to Build Your ADU?
If you’re considering building an ADU in San Diego and want to take advantage of these unique height allowances, it’s essential to understand the regulations thoroughly.
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