If you’re thinking about building an ADU but aren’t sure if your property meets the requirements--or what the requirements even are--this simple guide will help answer your questions and steer you in the right direction.
The good news is, it’s now easier than ever to build an ADU on your property! As of January 1st 2020, all California cities must approve ADU applications within 60 days, without requiring a hearing or discretionary review. Furthermore, cities cannot require the owner to live on the property, nor can they charge impact fees on ADUs less than 750 sq feet. Fees for larger ADUs may still apply, but are limited. And all homeowners associations must allow for the construction of ADUs.
There are size limits for ADUs, and they vary state by state. In California, an attached ADU cannot exceed 50% of the size of the main dwelling (so if your house is 1800 square feet, your attached ADU must be 900 square feet or smaller). Unattached ADUs have a size limit of 1,200 square feet, regardless of the size of the main house. Cities can't interfere with units under 800 square feet or 16 feet of height.
It’s worth noting that there are minimum interior space requirements as well. Essentially, the bedroom/living room must be at least 70 square feet and the kitchen must be at least 50 square feet. The bathroom must be at least 30 square feet and requires a toilet, sink, and shower or bathtub. This works out to a minimum of 150 square feet , or a space larger than 10 by 15 feet—they can be very small!
The short answer is that homeowners may build up to two ADUs on their property, but there are restrictions. Owners of multi-family dwellings can build up to two full-size ADUs on the property (if there’s enough space). Homeowners of single-family properties may also build up to two ADUs on their property: a regular detached ADU and a Junior ADU (also called a JADU). A JADU is a smaller unit that is attached to the primary dwelling, and it can extend up to 150 feet beyond the original footprint of the building. JADUs are usually converted garages or large bedrooms remodeled to include a bathroom and kitchen.
Yes, there are some building material standards in place to ensure quality. Windows must be at least double-pane glass and labelled for building use, and they can’t have exterior trim. There are also a few exterior cladding materials that are prohibited, including single-piece composites, laminates, and interlocked metal sheathing. The roof can’t be made of wooden shingles, and it must have a minimum of 2:12 pitch for more than 50% of the roof area.
Your ADU can be connected to your current electrical panel, provided there is enough space. But if you intend to rent the ADU, you should probably have its electricity metered separately. Most people choose to share the water connection though, as it is rarely worth the cost of separate metering. The ADU’s sewer line is not allowed to connect to the main house, and must connect to the sewer line downstream of the house.
Not necessarily, as California’s new ADU laws have eased restrictions on parking requirements. Homeowners who convert garages into ADUs--or tear down the garage to build a new unit in the same footprint--are no longer required to provide parking spaces. And no parking spots are required for units within half a mile of public transit or in an historic district. If you're building a JADU, you will be required to replace parking if you are renovating a garage.
Certain categories of ADU are now subject to automatic approval. This means that cities must approve ADU proposals without applying any local development standards--such as limits on lot size, unit size or height, parking, setbacks, or aesthetics--if proposed on a lot with one single-family home. So which ADUs are eligible for automatic approval? Garage conversion ADUs are, as long as the proposed ADU has its own separate entrance and setbacks deemed sufficient for proper fire safety. So are new detached ADUs no larger than 800 sq feet, with a maximum height of 16 feet, and rear and side setbacks of at least 4 ft.
Setback refers to the distance between the property line and the exterior wall of the structure(s) on said property. Current LA County building codes dictate that all new constructions must have a setback from the property line of at least four feet. Additionally, the ADU must have a ten-foot setback from the existing house. But if you’re converting your garage into an ADU, setback requirements do not apply. Another win for garage conversions!
In many cities, the permitting process is made purposefully complicated. Just submitting the permits can be expensive and time-consuming. Understanding building and zoning codes and restrictions can feel overwhelming. The easiest and most accurate way to find out if your property meets the qualifications for building an ADU is to schedule a free consultation with Homestead. Our team of award-winning architects can design the perfect ADU to fit your needs, while making sure all the paperwork is properly filled out and filed. And before you know it, you'll be taking the keys to your brand-new ADU.
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Having trouble figuring out ADU pricing? Learn more about average ADU construction costs vs "true costs" in this blog post.