Mother-in-law studio. Man shack. Rentable pied-à-terre. Granny flat. Whatever one calls the accessory dwelling unit, the twee bungalettes are blooming across town—wedged between homes, squatting in backyards, and perched atop garages. If you’ve got space, a modest ADU (800 square feet or smaller, generally around $150,000 to build) might seem a no-brainer—even a civic good, given that density is practically a Portland byword. But then, there’s the City of Portland’s daunting thicket of codes, permits, and taxes to navigate, all growing faster than your backyard blackberries. We prune back a few layers so you can budget and build your bliss.
In Portland, ADUs are capped at between 15 and 20 feet high and three-quarters the size of the main house up to 800 square feet. Further constraints: the distance you build from property lines, total ratio of your ADU to your lot, and features like roof pitch and window proportion. Local builders like Shelter Solutions and Hammer and Hand can concierge if you’re have trouble fitting puzzle pieces together. But regardless, gird yourself for application fees (building, land use, and site plan reviews) of about a grand.
Your shake-shingled, passively cooled, solar-powered tiny home has been approved! Now you need permits—lots of them. We’re talking mechanical and plumbing, multiple site surveys, Metro excise tax, zoning inspection, and site-specific fees for erosion control and special districts. Permitting can easily climb above $5,000, so start with the city’s online fee estimator. (If you ask nicely, the pros at the city’s Development Services might hold your hand.)
SYSTEM DEVELOPMENT CHARGES
Next, the doozy: administrative fees for water, transportation, parks, and environmental services. The charges intended to help city infrastructure keep pace with new development can total more than $17,000. Lucky for you, Portland issues the equivalent of a Monopoly get-out-of-jail card: an automatic SDC waiver, recently reextended through July 2018. Until then, new ADU owners don’t have to pay a cent. Still, keep a sharp eye out for a future city council change of heart.
About this time last year, proud new ADU owners in Multnomah County received a shock: property taxes that had as much as quadrupled. A raging debate ensued; this spring, the county assessor bowed to pressure and reversed the new formula (which interpreted an ADU on a single-family lot as a zoning change, unleashing property-tax hounds). Now, just like most other homeowners, county homes with new ADUs can expect a tax bump the first year, but then a max annual property tax hike capped at 3 percent.
STRANGE BUT TRUE ADU FACTS
- You may not have more than six roommates living with you in your ADU. (Bummer!)
- ADUs are not allowed on sites where one or more residents work from home and see employees and/or customers on-site. Examples given: “counseling, tutoring, and hair cutting and styling.”
- The exterior finish of your ADU must either match the main house or be a shingle, horizontal clapboard, or shiplap pattern. Get your shiplap on!