Small garden studio in a separate room with window walls.

How to Build an Accessory Dwelling Unit: A Guide for California Homeowners

When sufficient space is there to support one, an accessory dwelling unit is a great addition to any home. These versatile, practical, and increasingly popular structures help to address housing shortages while making life easier for thousands of homeowners across America each year.

If your home has become too small, either due to a growing family or changing needs and functions, an accessory dwelling unit (or ADU) is the perfect way to create extra space on your property. Use it as a spare bedroom, rent it out to a tenant, or house family members such as parents or grandparents.

Read on to find out more about what exactly an ADU is, recent updates in California ADU rules, and how you can build one.

What Exactly Is an Accessory Dwelling Unit?

An accessory dwelling unit is a permanent structure built on your property. It includes electricity, water, and sewer connections, making it just as functional and inhabitable as a regular home, only smaller.

ADUs are sometimes compared to tiny homes, but one important point differentiates the two: the laws governing them. Recently California laws, which are strict about tiny home regulations, have been created to incentivize and promote the creation of ADUs (read more now).

How To Build an ADU

When speaking to your contractor, generally they will offer you a few different options for your ADU build. The version you choose will depend on your budget, your timeframe, and what you’ll be using your ADU for.


This is generally the least expensive type of ADU. You will receive a set of predetermined plans with little scope for customization. This cost-effective option works well for those looking to rent out their ADU to tenants.


With this option, you’re taking some of the elements of the pre-designed ADU, but adding your own personal touches into the design. This option is great if you’re building the ADU for someone with specific needs.

Custom Design

With this option, you have complete design control over every inch of your ADU. If you want to create a space that’s completely your own, created to your exact specifications, and don’t mind paying a little extra then this option’s for you.

Furnishing Your ADU

Almost as important as the structure and architectural design of your new ADU is the decoration and interior design. There are a number of directions you can go in here, depending on the space’s intended use and what your budget is.

If you want to create a dwelling for a family member or carer, they might prefer to decorate their own space so they can feel comfortable in their new dwelling. If your new ADU is intended more as an extension of your home then you may want to reuse some of the furniture and furnishings from your main house, for a greater sense of cohesion between the two.

Build Your Dream ADU Today

An accessory dwelling unit is an extremely valuable and practical thing to have on your property, and thanks to the recent California law changes, it’s also something that’s likely well within your reach.

If you’ve found this article helpful, don’t forget to have a look at the rest of our DIY content today.

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