Accessory Dwelling Units (ADUs) offer homeowners the unique opportunity to put a second living space on the same property as their primary residence. Also known as granny flats, in-law suites, secondary dwellings, or a range of other names, homeowners are increasingly turning to ADUs to increase their livable space or alternatively, rent out their ADU as an alternative form of income. Whatever your indented purpose is, we’ve got you covered when it comes to buying an ADU in San Francisco.

What is an ADU?

Technically speaking, an ADU is a secondary dwelling unit that is on the same property as the primary residence. ADUs can either be attached to the primary home, above the garage for example, or act as standalone dwellings. It is important to note that ADUs are bound to the lot that they are on. Therefore, an ADU cannot be sold separate from the primary residence. Also, each municipality may have different rules that affect your ADU. Examples include:

If you live in an area other than the ones listed above, you can contact us here and we will be gladly assist you in finding the appropriate information.

Why Might You Want an ADU?

• Add Additional Living Space - because of their ease of construction, ADUs are a straightforward solution to increasing the amount of livable space on your property

• Another stream of income - ADUs are becoming a popular way to boost one’s secondary income. Because ADUs can be built separate from the main residence, once permitted, the extra space can be rented out as an additional stream of income

Key Decisions

• Size - Under California State regulations, your ADU is limited in size to 1,200 square feet or ½ the size of your primary residence, whichever is smaller. In most cases however, towns further limit the size of ADUs. Depending on the city, ADUs may be limited to just 600 feet in size. In spite of that, there are still plenty of companies that manufacture ADUs and deliver to the San Francisco Bay area.

• Standard vs. Custom - Many prefab manufacturers offer pre-designed models small enough to qualify as an ADU. However if you have specific  design requests or live on a tricky lot (small work area, hilly lot) your options for a standard design may be limited.

Common Questions

• How long does it take to build an ADU?

  • While the usual building time for a prefab primary residence is 1-2 years, the start-to-install time for ADUs can be significantly less. Some companies even have install times as quick as 6 weeks from the time of deposit.

• How much does an ADU cost?

  • Depending on variables such as location, designer/ manufacturer, and lot conditions may change your exact cost, your ADU will likely cost between $250-$500 per square foot.

• Is there financing available? If so, what options are available?

  • Yes. While individuals interested in financing a traditional prefab build might want to consider a construction loan or a temp to perm loan, buyers interested in an ADU may have a more advantageous financing option - a personal loan. With a personal loan:

    • Many personal lenders allow you to borrow up to $100k with no down payment

    • These loans are typically amortized over a shorter period than mortgages (up to 12 years)

    • These loans typically don’t underwrite the property and instead underwrite you as a borrower

    • Many of the best personal lenders are online and serve almost the entire country

    • The time to get approved for a personal loan is generally pretty fast (as little as a day to up to a couple weeks)

Reputable Companies that Build ADUs in the San Francisco Area:

• KitHaus

  • Make 4 models of modern tiny-homes perfect for use as an ADU

  • All-in-cost: $330-$550 per sq ft

  • http://kithaus.com/

• Honomobo

  • Offers 6 models of repurposed shipping containers that are suitable for usa as an ADU

  • All-in-cost: $270 - $500 per sq ft

  • https://www.honomobo.com/

• Cocoon9

  • Has 3 single-story luxury home models, ranging from 160 to 480 square feet.

  • All-in-cost: $780 - $800 per sq ft

  • http://cocoon9.com/

For a more complete list, see our list of the Best Prefab ADUs for Sale in the Bay Area