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Portland Design Build Remodeling Blog

Incorporating an ADU In Your Portland Remodel

If you live in or near Portland, Oregon, chances are good that you have heard about ADUs although you might never have noticed one. As a result of the city’s policies making the construction of accessory dwelling units legal on most single-family lots, Portland has made a name for itself as a pioneer in the field. It is easier than ever to incorporate an ADU into your Portland remodel, allowing for families to house another family or generate extra income. 

What Is An ADU?

An ADU — or mother-in-law apartment, or ancillary unit, or granny flat, or garden cottage, etc. — is a secondary living space added to a single-family home. It can be created in a garage, basement, or attic, it can be an addition built onto a home or a new detached structure, or it can be integrated into the plans for a new home. While ADU's are built in a myriad of ways, COOPER Design Builders can help you integrate an ADU into your homes current structure with a whole home remodel

Why Consider an ADU?

The reasons behind accessory dwelling units vary, but most involve bringing in additional income in the form of long-term or short-term rent. Some people build an ADU, move in, and rent out their main home. Others add a secondary living space for family members to use — the mother-in-law suite — while others are looking for a place for a home-based business. But most ADUs in Portland, according to a study conducted in 2013 by the state of Oregon, are rented to strangers for permanent residences.

Building Costs

The cost to build a mother-in-law apartment varies widely. A recent, private study of Portland ADU owners found that new detached units covering 400 square feet start at $125,000, and 800-square-foot buildings start at $180,000 but again, these are just starting points. Remodeling existing interior spaces such as a basement or attic could be a smart way to create a separate living space in lieu of a detached structure. In Portland's current housing market, you can expect to recoup an average of $1400 for a one bedroom ADU, or up to $2200 for a two bedroom ADU. 

A Different Mindset

An accessory dwelling unit has all the basics of a single-family home — heat, electricity, water, kitchen, bathroom, living space — but not everything that a single-family home contains. Portland limits ADUs to 800 square feet, or 75 percent of the area of the primary home, whichever is smaller. So people who build a home the size of a studio or one-bedroom apartment and move into it themselves have done some soul-searching about what’s important. Not only do they need to get rid of or store possessions elsewhere, they must downsize their expectations about how necessary a full-size refrigerator or a dishwasher is to them.

Numbers are Growing

Although the number of ADU permits issued in Portland has boomed the past few years — 615 in 2016, compared with 86 in 2010, the year Portland systems development charges were waived for ADUs — legal ADUs still are a small piece of the total housing picture in the city. Accessory apartments built without city permits over the years likely are numerous, but hard to count. And because they’re in the backyard, the basement, the attic, or the garage, ADUs aren’t visible to most passers-by. 

Information from the City

The city of Portland’s Development Services Department has a detailed website full of information for anyone interested in adding an ADU, including definitions and requirements, permit applications, and explanations of the plan review and inspection process. 

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