Carbon Cabin

Mercer Island, WA

Accessory Dwelling Unit, or ADU for short, can be a great addition to your property. There are two variations: attached (ADU) and detached (DADU) and both offer many benefits to the owner. To inspire you for your own DADU, above is an SZ fly-thru rendering, featuring a SIRE (Structurally Insulated Rammed Earth) wall.

1. ADU is a good response to urban sprawl. It relieves pressures on housing density allowing affordable rentals in high priced markets for people that otherwise wouldn’t be able to afford them.

2. ADU allows for multi-generational living.

• More families look to have their aging parents live close.
• Kids that go through a rough patch can use ADU housing until they get back on their feet.
• And, in many cultures, families choose to live close or even under the same roof.

3. ADU can also provide you with some extra income; pay down your mortgage or cover other expenses by leveraging travel platforms such as AirBnB, VRBO, or Trip Advisor.

If you are considering an ADU, make sure you understand what your local jurisdiction allows.

ADU 101: (as it relates to Mercer Island, WA)

First, only one ADU is permitted on the property of a single-family residence. The following requirements must then be met. (for more specific code details, click here).

1. The owner must live in one of the dwellings (primary house or ADU).
2. There are restrictions to the number of occupants that can live in the ADU.
3. Size and scale minimums and maximums exist: 220-900 square feet.
4. There can be only one entrance on each front or side street of the residence.
5. The design must be consistent to existing structures on the property (relates to DADU).
6. Certain parking requirements must be met.

As with all construction there are many hurdles to overcome, but if an ADU is right for you, it’s well worth the effort.