what exactly is a DADU?

What exactly is a DADU? And how can I build one?
Historically, Seattle hasn’t been a particularly dense city, with very few duplexes and triplexes compared to other cities of similar size. But right now the city is going through a lot of changes with increasing populations and decreasing housing stock. And with these changes comes a dire need for more housing stock.
None of this is surprising to anyone living in Seattle. And this is why so many people are interested in learning more about DADUs – not to mention the possibility of an additional income in an increasingly expensive city. 
But, if you’re looking for quick, easy, money – you’re probably looking in the wrong place. (If you find the right place, be sure to pass along the word!). But, if you’re willing to spend the time and money to do it right, it can provide a great source of income for your family – or can act as a place for aging family members to stay!
For starters, you should first decide if what you need or want is truly a Detached Accessory Dwelling Unit (DADU). For example, if you wanted a long term guest suite separate from your house (perhaps a bedroom, bathroom, and living room) but don’t require a kitchen because your family members will be eating with you- you don’t necessarily have to comply with the DADU regulations. This means different (and typically more lenient) requirements as far as size, height, and parking. This can be a great option for extended family members as you will have a lot of flexibility with the design, provided that you don’t require they have a truly separate apartment.

If your goal is to provide a source of rental income (rather than provide housing for family members) then you will definitely need to build a DADU, since you’ll need to provide a kitchen in addition to the bed, bath, and living room. And remember, you’ll need to live in one of the units (you can live in the larger and rent the smaller – or vise versa). Frequently, determining the best way to design and build a DADU is game of tetris. There are a lot of factors that determine where and how you can build your DADU:
  • Ensure that your property is a minimum of 4000sf. At this time, Seattle lots smaller than that do not allow a DADU. 
  • The size restrictions are 800sf total. This includes a garage if it is part of the DADU, and includes all stories (not just the footprint). Additionally, there is a limit to how much of your lot you can cover with building – typically, 35%. Depending on the size of the existing structures on your property, you may be limited by more than the 800sf.
  • Ensure that you can provde 2 parking spaces (one for the main house and one for the DADU). There are some exceptions to when you are required parking, but most projects will require two spots. Furthermore, Seattle has some very specific rules about where on your property the parking can be located. This often becomes a tricky problem to solve, as many properties have difficulty providing access to additional parking without expense. 
  • Remember that the height limits for DADUs are lower than for a typical single family home. 
  • Allow yourself ample time for design and construction. The permitting and building processes typically take longer people expect, but building a DADU is a long term project, well worth the time and effort.
If you’re able to comply with all of these requirements – a DADU can be a fantastic opportunity for increasing income, improving your family’s quality of life, or both!