What is an Auxiliary Dwelling Unit?

Hi everyone.  This is my first blog, so please be patient as I learn and improve.  I only have one semester of high school creative writing under my belt! 😊 This month’s topic is auxiliary dwelling units, or ADUs.  An ADU is defined as a self-contained unit, either attached or adjacent to a primary residence.  Read on for more information.

As I mentioned, an ADU is a self-contained housing unit.  It has a living area, kitchen, minimum ¾ bathroom and one, possibly two, bedrooms.  They are typically under 1000 square feet by code, although some authorities having jurisdiction (AHJ) may allow something larger.  This does vary according to your local AHJ, so either you or your designer needs to determine this. 

There does need to be a primary residence on the property, and the homeowner needs to live in either the primary residence or the ADU.  Failure to do so could result in the ADU having to meet additional code requirements.  They often need at least one dedicated parking space, although there are exceptions in dense urban areas that do not offer off-street parking.

What can an ADU be used for?  Lots of things, of course.  Typically, it is a rental property, either long-term or transitional (i.e. vacation rental).  But it can be used as your residence while you rent out the larger building on site.  You can also use it as a home office or recreational use.  It’s also popular to use them for family housing (either senior or junior family members).

An ADU can be built several ways.  It can be attached to an existing structure, part of a completely new building, a new detached structure, or a converted existing structure, such as a detached garage.  Things to consider when deciding what type of ADU to build are the size of the lot, the size of an existing space, or the ability to convert an existing detached structure and being sure it meets code without becoming cost prohibitive. When building something new, location can be critical.  If you have an alley, a corner lot, or the ability to have a separate driveway, this improves privacy for everyone when the entrance faces away from the primary residence.  Are you thinking vacation rental?  A scenic view may positively affect reviews left by users on websites, which increases bookings.

Should you hire a designer to draw up the plans?  That depends.  Are you creative, do you have the design software, and knowledge of codes?  If you answer no to any of these questions, you may want to consider hiring a designer.  In any case, at a minimum you will need to have an engineering firm review them, if you don’t use prescriptive designs (more about those in a future blog).

Well, that wraps up this blog post.  Do you have any thoughts or questions?  I want to hear them.  Need a designer?  I would love to help.  Thank you for reading this blog, and until next time, take care, and remember, your house is your dominion!


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