Build your own

ADU

Accessory Dwelling Units

The key to affordable housing is in your own backyard... building an ADU can maximize space, income and value  

The need for affordable housing has never been greater in California, and ADUs have emerged as a popular solution. This page outlines everything you need to know about ADUs, and why you should consider building one on your property.

What are ADU's?

ADUs are secondary housing units on a single family lot. They are typically under 1000sqft.

Types of ADU Homes

  • Detached new construction (Also known as cottages, granny flats, laneway houses)
  • Garage conversions
  • Above garage or workshop (Also known as garage apartments or carriage houses)
  • Addition bump out
  • Basement conversion
  • Internal (Part of the house, besides the basement, is converted into an ADU)

Reasons for Creating More Usable Space

Versatile space could be used for:

  • Workshop/studio space/ home office
  • Guest suite for visiting family and friends
  • Extra play space for kids and/or pets
  • Permanent living space for a parent or new family member (au pair)

Pros of Building an ADU:

  • Provide flexible dwelling options in central city neighborhoods
  • Utilizes existing governmental infrastructure ( EG. roads, sewers, schools)
  • Small environmental footprint. Smaller residential spaces use less energy in construction, deconstruction and habitation
  • Creates more affordable housing options in residential neighborhoods
  • Extra income
  • Added value to your home when you decide to sell

A Few Great Things to Know about Building An ADU:

  • Only one accessory dwelling unit is allowed per lot.
  • The total floor area of a Detached ADU shall be no less than 275 square feet, nor more than 1,200 square feet. The ADU, if attached, shall not exceed 50% of the floor area of the existing residence.
  • Side and rear setbacks are four feet minimum from property lines. Setbacks are not required if the ADU replaces existing structures within the required setback area.
  • Tandem parking in driveways is permitted. Additionally, ADUs built within a quarter mile of a BART station and located within an RPP zone require no additional parking spaces.
  • One story units are allowed.
  • No design review is necessary for an ADU permit.
  • The entrance of a second unit shall not be visible from the street.

Cost Of Building an ADU:

  • The cost per square foot range $162-$682/sq ft.
  • The cost per square foot average was $305 per sq ft in 2019.
  • The costs for ADUs can vary by type, detached being the most expensive.
  • The average cost of an ADU in California was $156,000, while the average cost of affordable units statewide was $332,000, and even higher in cities like San Francisco ($591,000 per unit) and Los Angeles ($372,000).
  • The cost of construction for the same structure can vary greatly depending on the builder, as well as what the current cost of labor and materials are in a given region.
  • It will also largely depend on what type of structure we’re talking about. A basement ADU conversion is a totally different animal than an ADU above a garage. These factors all make estimating the “average cost of an ADU” impossible.

Whatever the reason for wanting to build an ADU, there are definitely a few things to consider.

If you or your client are thinking about building an ADU, I’d be happy to meet and discuss your options and plans for a 1 hour free consultation.

Permitting accessory dwelling units isn’t straight forward. We help by navigating and understanding the constantly changing regulatory environment of the many jurisdictions in Northern California so we can knowledgeably inform you of all the laws, requirements, and regulations.

We’ll inform you of all options, scope and feasibility for every ADU project, so you can focus on the benefits of your new ADU home.

KC Custom Builders has the knowledge, experience and expertise to craft your new, quality ADU home  

You can trust in us as a leader in quality and experience to deliver the results you desire from a home builder.

“I have been with KC Custom Builders for years. They have done my house, my rental and my office. Always perfectionists, always prompt, always reliable and always reasonable price-wise. It is such a pleasure to work with professional like Nathan and his company. A hard to find commodity it seems, these days. They will be my first choice for all my future projects.” – Joel B. | Lafayette, CA

Let's build your NEW ADU home

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