An accessory dwelling unit (ADU) is an attached or detached residential unit that serves as a separate living facility for one or more people and can only be built on a property with an already existing residence. ADU’s include permanent living, sleeping, and eating areas, as well as accommodations for cooking and sanitation. All of which are located on the same property as the primary residence.

A junior accessory dwelling unit (JADU) is a unit located within a single-family residence that does not exceed 500 square feet. It includes sanitation accommodations that are either separate or shared with the existing residence.

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To start off your ADU home process, you need to have a topographic survey done to establish lot line locations. Once this is completed, a site plan of the property is created, which will allow you to visualize the addition of your ADU along with the primary residence already existing on the property. At Westcon Engineering, Inc. we can provide the topographic survey and site plan creation for you. And from there, we can work together to create your fully customizable ADU dream home based on your desires within city standards.


When designing your ADU home, it is important to keep in mind the rules and regulations that must be met to be able to build. Below is a summary of the general standards for both ADU’s and JADU’s.

Accessory Dwelling Unit (ADU) Standards:

For an attached ADU, the floor area must not surpass 50% of the floor area of the primary housing unit, with the limit being 1,200 square feet. For a detached ADU unit, the floor area cannot surpass 1,200 square feet. If other requirements such as floor area and the 50% threshold are not met, the city will allow an 800 square foot unit to be created if it does not surpass a building height of 16 feet and has 4-foot side and rear setbacks.

Junior Accessory Dwelling Unit (JADU) Standards:

You are only allowed one JADU per single-family residence and it must be built within the single-family residence. The maximum size for a JADU property is 500 square feet, but an addition of 150 square feet can be made to accommodate entering and exiting your JADU. It also must include its own entrance, separate from the entrance to the existing single-family residence, but it can share a bathroom or shower with the primary residence. Each JADU must also include a kitchen with a cooking area with appliances, reasonably sized storage cabinets, and sufficient counter space.

Prefab Design Features:

When it comes to designing you ADU home, using the prefab ADU’s makes the entire process amazingly simple and easy. You are free to customize your home in any way you choose. The interior, exterior, and floor plan are all up to you. Some customized features include granite countertops, raised bedroom ceilings, and freestanding bathtubs.


At Westcon Engineering, Inc. we are more than capable to handle your processing and approval of your site plan. The state of California utilizes minimal processing of ADU’s or JADU’s. Once your site plan is submitted to the city, your approval process begins. Only a building permit and related permits are required for approval. And once your plans are submitted to the city for approval, you are guaranteed to be approved within 60 days even if no hearing or review has been held if everything is up to the above-mentioned standards.

We hope to work diligently with you to create, design, and approve your site plan. The President of our company, Kathyjo McCloskey, is available to consult at an hourly pay for anything you may need throughout this process. And as an expression of our gratitude, we will waive the consulting fee if you choose our company for the surveying and processing of your ADU home. We are excited to work with you on designing and approving your ADU unit.

Click here to check out our ADU press release!