Have you been wondering why your neighbors are all talking about building an accessory dwelling unit (ADU)?
They’re probably trying to make the best of the housing market right now. Given the rising mortgage prices and dwindling options, it’s not exactly the home buyer’s dream. But ADU gives you more space to maneuver.
With an ADU, you can increase your property’s usability and value. It also gives you the option to generate rental income. Many people opt for these alternative options due to their affordability—something that is needed in the face of housing shortages.
If you’re curious about ADUs and are considering building one on your property, you’ve come to the right place.
Below, we’ve outlined all you need to know about ADUs to help you make informed decisions moving forward. And if you do decide to build one, you can take up the project successfully.
Let’s start with the basics.
Table of Contents
What Is an Accessory Dwelling Unit?
Accessory dwelling units, or ADUs, are independent living spaces built on the same lot as a single-family home. While they may share the foundation with the primary structure on the property, ADUs must have their own legal access to water, sewer, and utilities, along with fully functional spaces for the kitchen, bathroom, living room, and bedroom.
These units can be bought or sold separately, rented out, or used as additional living or working spaces for the family.
Building an ADU requires a permit from local authorities. It may not be legal in some jurisdictions.
Types of ADUs
ADUs can be categorized into different groups based on where they are built.
Here are some of the most common types of ADUs:
1. Attached ADUs
Attached ADUs share a wall with the primary home and are often built on the side or rear part of the existing structure. They have a separate entrance.
They are also fully functional living spaces, though they may share utility hookups with the main residence.
2. Detached ADUs
These types of ADUs are the opposite of attached ADUs. They are fully functional and independent living spaces with separate entrances and don’t share a wall with the main house.
3. Junior ADUs (JADUs)
JADUs are built in the space of the primary house on the property, within the same walls. They’re not visible from the outside and take up less than 500 square feet. They are often built-in attics, basements, or spare rooms that may or may not share sanitation facilities with the primary structure.
4. Garage Conversions
These are garages that have been converted into fully functional living spaces. They’re an ideal solution for those short on living areas and don’t need the parking space.
Benefits of ADUs
Regardless of what type of ADU you plan to build, you will surely enjoy many perks.
From monetary benefits to improved property value, here are some reasons to consider building an ADU on your property:
Affordable and Cost-Effective
The main reason to build an ADU is because it is a very affordable type of construction. In most cases, you don’t need to build an ADU from scratch but only need to add some utilities and certain functionalities.
Some states like California also promote ADU construction, where they remove the following restrictions:
- No need to occupy the primary residence or the proposed new structure
- No impact fee for ADUs smaller than 750 square feet
- Builders can apply for ADU permits regardless of how the lot or home is situated
- No need to meet off-street parking requirements if homeowners convert their garages into ADUs
Applicants in California can also maximize the number of ADUs by ensuring they aren’t less than 850 square feet (1 bedroom ADU) or less than 1000 square feet (1+ bedroom ADU).
Value Addition
Adding an ADU to your property can significantly increase your home’s value. In some cases, such an addition may also lead to tax benefits.
Increased Usable Space
ADUs give homeowners added usable space, which they can use as work-from-home spaces, guest rooms, or rental units. If you have extended family staying with you for a vacation or ones that you need to care for, you’ll greatly appreciate the privacy that ADUs provide.
Source of Income
Homeowners can also use their ADUs as a source of income by renting them out.
Tips on Building an ADU
There are many things to keep in mind when building an ADU, especially before you begin planning:
- Check your region’s zoning laws before getting started with the design planning.
- Measure available interior space before buying new furniture and appliances.
- Choose durable materials that are also sustainably sourced.
- Optimize available space and go for flexible storage solutions.
- Paint small spaces in light colors and decorate them with mirrors to make them feel spacious, light, and bright.
- Consider outfitting the space with all the amenities required for a comfortable holiday or workation.
- Factor in safety features, such as fire extinguishers, safety exits, smoke detectors, etc.
- Integrate as many windows, light fixtures, and height to bring in more light.
- Add outdoor space (with plants) into the ADU package if possible.
- Incorporate a separate entrance for your ADU.
- Give your ADU and its occupants privacy with fences, gates, doors, or barriers.
Financing Options for ADUs
If you’re looking into financing options for ADUs, renovation loans might be a good solution. If you have an existing mortgage, refinancing it is another affordable option if you’re looking for low interest rates.
If you’re in California, you can also look into state grants and incentives for building ADUs.
Build Your ADU With Golden Shore
Despite how easy it looks, researching and building an ADU on your property is a challenging project to take on yourself. Our experienced team can help ensure you get everything you need, whether it is tips on designing ADUs or assistance with zoning requirements.
Do you have more questions about building ADUs or want to start planning your ADU project? Golden Shore is here to help. Let’s get in touch to begin!
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ADU Anxiety? Your Guide To A Legal And Profitable Build
People Also Ask
When building an ADU, common mistakes include underestimating the total budget, failing to secure proper permits, and overlooking zoning restrictions specific to your lot. Many homeowners also choose the wrong contractor without verifying local experience, which can lead to costly delays. Poor site planning, such as ignoring utility connections or setback requirements, often causes major setbacks. To avoid these pitfalls, thorough research and professional guidance are essential. For a detailed roadmap, Golden Shore Design and Build recommends reviewing our internal article San Diego ADU Construction: A Step-by-Step Guide From Lot Evaluation To Certificate Of Occupancy, which covers every phase from lot evaluation to certificate of occupancy, ensuring you navigate the process smoothly and avoid costly errors.
The return on investment for an Accessory Dwelling Unit (ADU) in San Diego is generally very high, often ranging from 70% to 80% of the construction cost added directly to your property value. However, the real financial benefit comes from the consistent rental income an ADU generates, which can yield an annual cash-on-cash return of 8% to 12% or more, depending on location and finishes. For homeowners in markets like Chula Vista or La Mesa, this makes an ADU one of the most lucrative long-term investments. To see how this compares to other projects, we recommend reading our detailed guide, The Top 3 Renovations With The Highest ROI In San Diego Right Now, which breaks down the best value-adding renovations in our current market.
For properties in San Diego, Chula Vista, National City, La Mesa, and Spring Valley CA, the maximum size of an Attached or Detached Accessory Dwelling Unit (ADU) is generally capped at 1,200 square feet. However, local zoning laws and your primary dwelling's size can influence this limit. For example, on a lot with an existing single-family home, the ADU cannot exceed 50% of the primary residence's square footage. Additionally, height restrictions and setback requirements may further reduce buildable area. It is crucial to verify these specifics with your city's planning department before designing. For a comprehensive guide to navigating these rules and ensuring a profitable project, please see our internal article ADU Anxiety? Your Guide To A Legal And Profitable Build. Golden Shore Design and Build recommends consulting a professional to maximize your allowable square footage legally.
The $25,000 ADU grant is a state-funded program available to homeowners in San Diego, Chula Vista, National City, La Mesa, and Spring Valley CA. This grant helps offset costs for designing and building an accessory dwelling unit on your property. To qualify, you typically need to meet income limits and use a licensed contractor. The funds can cover permits, plans, and construction. At Golden Shore Design and Build, we guide clients through the application process to ensure compliance with local zoning rules. This grant makes ADU projects more affordable, but it is competitive, so early preparation is key. Contact your local housing authority for specific eligibility details.
