Portland made the fourplex actually pencil

Yes. Up to four units (a duplex, triplex or fourplex) are allowed by right on almost any lot in Portland’s single-dwelling zones, subject to size and scale limits. "By right" means it is a permitted use: if your design fits the objective standards, the city approves it without a rezoning or a discretionary hearing. The fourplex is in fact the most popular choice under the rules, because it unlocks the most floor area per lot.

You can build up to six units on a site if at least half of them are affordable to households earning up to 60% of the median family income. This is the "deeper affordability" bonus that Portland built into the rules deliberately. The affordable units carry a recorded covenant certified by the Portland Housing Bureau: for rental units the affordability lasts 99 years at 60% of median income, and for for-sale units it lasts 10 years at 80% of median income.

FAR means floor area ratio, the total building floor area divided by the lot area. Portland’s breakthrough was to set a higher FAR for each additional unit. On a standard R5 lot, a single house is capped at 0.5 FAR, a duplex at 0.6, a triplex at 0.7, and a fourplex at 0.8, so four homes are allowed about 60% more building than one house. This is the opposite of most cities, which let a big single house use as much floor area as four small homes, and it is the main reason Portland’s reform actually produced middle housing instead of just legalizing it on paper.

No. RIP removed the off-street parking requirement across the single-dwelling zones, about three-quarters of the city’s residential land. You can add parking if you want, but the city does not force you to, which frees up the lot for the building and can be the difference between three units fitting and four fitting.

RIP Part 1 covered the R2.5, R5 and R7 single-dwelling zones. RIP Part 2, effective mid-2022, extended the middle-housing rules into the lowest-density R10 and R20 zones as well, and added cottage clusters and attached houses (townhouses) citywide. In practice that means the middle-housing options now reach essentially all of Portland’s house-zoned land.

Yes, and you may earn a bonus for doing it. Retaining an existing home while adding new units qualifies for the same higher tier of floor area as the affordability bonus. This makes it attractive to add two or three new homes behind or beside a house you keep, rather than demolishing and rebuilding.

Yes. Portland allows middle-housing land divisions under Oregon’s Senate Bill 458, which let each unit sit on its own separately-ownable lot. Being able to sell the homes one at a time, rather than holding the whole building as a single rental, is a major reason the numbers work for small builders and owners.

A cottage cluster is a group of at least four small detached homes, each with a footprint under about 900 square feet, arranged around a shared common courtyard. RIP Part 2 allowed cottage clusters citywide, including in the low-density R10 and R20 zones, giving owners of larger lots a way to add several small homes while keeping a detached, low-rise character.

A lot, by the standard of these reforms. From August 2021 to mid-2024 the city permitted more than 1,400 middle-housing and ADU units in single-family zones, and the share of the city’s total new homes coming from those zones jumped from 23% in 2023 to 43% in the first half of 2024. Middle housing became the most common type of home being built in the single-family zones, the outcome most other cities hoped for and did not get.

Yes, by a wide margin. In 2024 a new market-rate middle-housing unit averaged about $460,000, while a new detached house averaged about $916,000, roughly half the price. That gap is the practical payoff of the reform: it put new-construction ownership within reach of buyers who could never afford a new single house on the same land.

The Sightline Institute gave it that label because of the FAR-by-unit design. Most cities that "ended single-family zoning" kept the building-size rules so tight that middle housing did not pencil out. Minneapolis is the classic example, where triplexes were legal but barely built. Portland instead rewarded more units with more building and removed parking mandates, and the production numbers followed. It is the reform other cities, including in British Columbia, are now studied against.

Yes. Both RIP Part 1 (2021) and Part 2 (2022) are in force, and no repeal or major amendment has occurred. The most recent city milestone is the January 2025 progress report measuring what got built. The rules that let you build up to four units, or six with affordability, remain fully in effect.

The City of Portland offers early-assistance appointments for residential infill projects, where staff review your lot and options before you file a full application. Because the floor-area math and the affordability covenant terms decide whether a project works, using an early-assistance meeting to confirm your FAR tier and unit count is worth doing before you spend on design.