5 Tips for Building Your Walnut Creek In-Law Unit

Do you want to add more living space to your property in Walnut Creek by building an in-law unit? In-law units or granny flats add considerable value to your property while offering comfort and private accommodation for your relatives, friends or guests. The good news is that due to the shortage of housing in Walnut Creek, the law has now changed to allow Accessory Dwelling Units (ADUs), more commonly know as in-law units or granny flats. Here’s what you need to know about building your in-law unit in Walnut Creek.

1.   Understanding Accessory Dwelling Units

An accessory dwelling unit (ADU), sometimes known as Secondary Dwelling Unit (SDU), is the official name given to an in-law unit or a granny flat.

An ADU is defined as a room or set of rooms that has been built and designed to be a separate dwelling, although it is in a single-family home or in a single-family zone. Accessory Dwelling Units are useful as they maximize the living space on a property, while still maintaining privacy and functionality for separate families or individuals.

Accessory Dwelling Units usually include sleeping, kitchen and bathroom areas, along with living space and a lockable entrance. There are both attached ADUs, which are attached to the main house, or detached ADUs which are contained in a separate structure (usually in the backyard).

2.   What’s Allowed for my In-Law Unit?

The goal of an in-law unit is to maximize living space, comfort and privacy, while keeping occupants close by on the same property.

For Walnut Creek, in-law units are allowed in all residential zones that have a single-family home on the lot. The ADU can be an attached or detached structure but can only be a single story. The exception is where an ADU is built over a garage, in which case the structure can be a two story.

3.   What’s Not Allowed?

Portrait of senior woman adding olive oil to saucepan at kitchen counterThere are some limitations on the design and structure of a Walnut Creek in-law unit.

An in-law unit or granny flat cannot be more than a single story, with the exception of being built over a garage.

There are also limits on how large you can build your in-law unit. This usually depends on the size of your lot and your existing home, as well as the degree of coverage on your lot. In general, ADUs can’t exceed 50% of the size of the main home.

You can’t build your in-law unit with a radically different architecture to your existing home – basically, any additional structure needs to fit in with your current design and style.

In-Law Units also can be built for the purpose of short-term rental without a Conditional Use Permit, and they can’t be taller than 18’0”.

4.   In-Law Units Need Special Design

An accessory dwelling unit needs to be designed and built in a way that’s consistent with the existing home. That’s why it’s almost essential to work with an architect, or design-build contractor when constructing your in-law unit.

In-law units are also a lot smaller than regular homes, with most between 700-950 sq. ft in size. This means that the design needs to maximize the area available to create a usable living area in such a small space.

ADUs need to be designed with mechanical, electrical, and plumbing needs in mind, as these will be integrated in the final structure.

Finally, it’s important to consider that any landscaping, tree removal or front door installation required for your ADU will need to be reviewed by the city before you can start construction.

5.   There’s More Than Structure to Consider

When considering the design for your ADU, start by thinking about how it will be used. How many people will live there? What are their needs? Have you taken into account fire sprinklers? What about integrating sustainable design with the use of solar panels or water conservation installations?

Thinking about these questions and discussing your options with an experienced design-build contractor means you get the best outcome and add utility and value to your property with your Walnut Creek In-Law Unit.

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