high rents
affordable housing
aging in place
neighborhood character
sustainable development
local investment


… as Portland continues to grow, we all struggle with development pressures that impact the fabric and character of our community. We believe that ADU’s offer powerful solutions to these challenges, especially in some of our denser residential neighborhoods. A well-designed ADU provides opportunities for aging in place, creates affordable housing opportunities, and promotes greater diversity and more housing choices. Some homeowners choose to downsize their lifestlye and move into their ADU while renting their home, using the rental income to allow them to keep a property that might otherwise be hard to afford.

In many neighborhoods, insensitive redevelopment is having an adverse impact on the quality of the streetscape. Developers tear down a perfectly good old home to build something larger, or partition the lot to add density. ADU’s are a better way to add that density, preserve the primary home along the street, and avoid sending a perfectly good house to the landfill. An ADU can be an excellent way to add square footage to your home while you need it (for kids, or a home business), and convert it to a rental or in-law unit as your family’s needs change. For all these reasons, an ADU can be a good strategy to extend the life of your home and your time in it. As a landlord, building an ADU on your rental property is a very profitable way to expand your portfolio without a significant increase in overhead, tax exposure, or service utility costs.

Nicholas Papaefthimiou | AIA


infillPDX was founded in 2014 by Nicholas Papaefthimiou, who continues to lead the design and development efforts. Nicholas is a licensed architect and contractor with more than 20 years’ professional experience across the United States and Europe. He holds Masters Degrees in both Architecture and Structural Engineering from the University of California, Berkeley and Bachelor of Science degrees in both Architecture and Urban Planning from the Massachusetts Institute of Technology.

Nicholas believes infill development provides superior housing opportunities for low-income residents, and in partnership with local agencies like JOIN and Central City Concern, his firm retains and manages a portfolio of houses and ADU’s as housing targeted for individuals and families transitioning out of houselessness.  In 2018 infillPDX was part of a team selected by the Meyer Memorial Trust to participate in the Small Homes Northwest pilot project, which is using a community-based ADU development process to highlight the synergies between government, community-based organization, and private-sector housing models. In addition to his professional work, Nicholas has served on multiple design and awards juries, organized and presented at numerous symposia, and served on several graduate school admission boards. He teaches courses in housing design, infill development and construction technology at both Portland State University and the University of Oregon.

Mia Sheperd


From studying engineering in university, working in lighting design in Portland, and then moving to Rwanda, Mia’s had the opportunity to work on a range of sustainability and development work across the globe. Mia has been designing ADUs for infillPDX since July of 2021. She recently started her own construction company, Block Design Build LLC, as a project manager and general contractor for ADUs. She is familiar with sustainable design framed by LEED, Passive House, Net Zero, and Living Building Challenge certifications as well as building with earthen materials. Mia believes engaging the community and recognizing the history of the land, including its origins, are key elements of the success of all her projects.