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Home Visit: Internal Lower Level ADU

Portland, Oregon | 795 square feet

Lower Level ADU

Photo by Melissa Stanton, AARP

The door to the right of the garage leads to a ground-floor ADU with windows along the back and side walls. The upper-level windows seen below are part of the main residence.

“We were looking for a way to live in our house for the rest of our lives and to generate at least some income in the process,” Robert Mercer and Jim Heuer wrote for the program guide of the annual Portland ADU Tour when their home was part of the lineup. “An ADU offers the possibility of caregiver lodging in the future or even a place for us to live while we rent out the main house if we get to the point where we can’t handle the stairs any longer.”

THE SOUND OF SILENCE: Internal ADUs often require that soundproofing insulation be installed between the primary dwelling and the accessory unit that’s below, above or beside it. In Portland, the building code for duplex residences requires a sound insulation rating of at least STCC45. To property owners thinking about a similar ADU setup, the duo advise: “Think about how you live in your home and how having downstairs neighbors will change what you can and can’t do with your space and what investment you are prepared to make in sound insulation.”

AN ADDED BONUS: “We are pleased that we have been able to provide more housing density on our property and still be in keeping with the historic character of our home.”

Design: DMS Architects
Builder: Weitzer Company 
Cost to build: $261,000 in 2016

Article adapted from the 2017 ADU Tour project profiles on and The ABCs of ADUs by AARP.


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