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ADUs: Image

Accessory Dwelling Units (ADUs)

What is an ADU? Accessory dwelling units (ADUs), in short are separate, smaller living quarters on the same lot as a house. They are known by many names including; mother in-law unit, granny flat, guest suite, home studio, garage apartment or conversion, tiny house, or cottage. 

Thinking about building an accessory dwelling unit in Portland? This is a great time as many of the site development charges (SDCs) are still being waived. That’s a savings of $12-20k in fees paid to the city for building a new residence. This waiver of fees will be reviewed again and is currently set to expire June 30, 2020. Portland is known as the leader of ADUs and as the friendliest place to build one in the US.

In regards to funding, currently home equity line of credit (HELOC) interest rates are still historically very low, take advantage of these long term savings in addition to the fee waiver. The cost of construction materials is also continually rising so if you’re interested in an ADU, now is a great time to get started.

All residentially zoned lots are eligible to add an ADU except lots with multifamily or duplex housing. That means if your lot begins with the letter R you most likely can build an ADU. The typical single family home is an ideal candidate (you can check your zoning at A single family home that is used as a rental can also have an ADU added to it, there is no owner occupancy requirement in Portland.

ADUs can be attached to your current residence, a finished basement or attic, or free standing structures (detached). Which one you choose is mostly based on your specific home site and needs. When you choose to add square footage (as opposed to finishing a basement) you are expanding your home's value even more as the square footage of the new rooms gets added onto the existing numbers. 

We are happy to do a free consultation on site with you to discuss your goals and options.

Reasons people build an ADU

·      A place for family members to live close by without sharing walls

·      To earn rental income which can help you with your mortgage. According to Portland State University’s study, ADU’s average $1,200 to $1,500 a month rent.

·      To help with Portland’s housing shortage, which has been in a state of emergency since 2015.

·      To downsize, many people build an ADU and rent out the main house to gain fincancial freedom, or scale back their carbon footprint.

If your plans were not submitted to the city before June 2018 you are not allowed to rent your ADU as a short term rental (on Airbnb) for 10 years unless you pay the hefty SDC fees.

What Indifab offers to homeowners who are interested in ADUs

·      Customization, prefab units are very small (~450 sq feet) and their standardized layout and size means they may not be ideal for your lot

·      Experience with the city of Portland and it's permitting phases for all types of ADUs

·      Full service – we design, permit and build

Something most people don’t realize is the amount of time it will take to get your plan approved by the city. There are many boxes that must be checked through the city’s design review and they are very specific and ever changing. Indifab will guide you through this process, taking care of all details. See the resources section below for a link to the city’s ADU requirements if you'd like to learn more.

The process in a nutshell

  1. Consultation on proposed site with an estimate that will help you decide on funding for your project.

  2. Indifab will design for your specific site. We are dedicated to meeting your goals for affordability, equity and sustainability.

  3. Plans are drawn and submitted to the city for review.

  4. Building permits are issued by the city.

  5. Construction of new ADU.

  6. Final inspections.

  7. After final inspections you will receive an occupation certificate from the city.


·      ADU requirements by city of Portland -

·      SDC waiver program -

·      What plans do you need to build?

·      General info by a Portland Realtor discussing why you may want to build an ADU

*    Is Portland the Best Place in the Country to Build an ADU?

ADUs: About
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