What is the Portland Residential Infill Project?
Answered by AskBaily Editorial · Updated
Short answer
The Portland Residential Infill Project (RIP) is a 2020 zoning reform that legalized duplexes, triplexes, and fourplexes on most single-family lots in Portland, Oregon. RIP also increased ADU allowances, allowing up to two ADUs per single-family lot (primary residence plus one or two ADUs). RIP was among the most aggressive pro-housing zoning reforms in a major US city.
In detail
The Residential Infill Project (RIP) was adopted by Portland City Council in August 2020 after a multi-year planning process. It fundamentally changed Portland's residential zoning by legalizing small multifamily (duplex, triplex, fourplex) on lots previously zoned single-family only.
What RIP changed:
- Fourplexes legalized in R2.5, R5, R7, R10, and R20 zones (previously single-family only).
- Bonus density for affordable units — up to 6 units per lot if at least half are affordable.
- ADU cap raised — up to two ADUs per single-family lot (one attached, one detached, or two detached depending on zone).
- Size limits — RIP imposed size caps on new construction to prevent mega-houses, which shifted development toward smaller, more numerous units.
- Demolition restrictions — new rules to protect existing housing stock.
Key RIP zones and their standards:
- R5 — most Portland single-family. Under RIP: up to 4 units as of right, up to 6 with affordability.
- R7 — slightly lower density. Up to 4 units.
- R10, R20 — lowest density. Up to 4 units in R10; 2 units in R20.
- R2.5 — highest density in RIP scope. Up to 4 units.
Maximum building size under RIP:
- RIP introduced size caps based on lot size to prevent bulk.
- Sliding scale: smaller lots cap total building size relatively lower.
- Aimed at preventing mega-houses from being built under permissive density rules.
ADU specifics under RIP:
- Maximum ADU size: up to 800 sqft.
- Up to 2 ADUs per lot in many R zones.
- ADU setbacks: 5-foot minimum.
- No replacement parking required.
- Short-term rental subject to separate regulations.
Post-RIP development patterns:
- Many Portland lots now see 2-4 unit development (duplex, triplex, fourplex) where a single-family home would have been the only option.
- Detached ADUs remain popular for homeowner-occupied projects.
- Infill development is active throughout Portland's eastside.
Portland permit process:
- Bureau of Development Services (BDS) handles residential permits.
- Trimet online portal for plan review submission.
- Typical residential remodel: 6-12 weeks plan review.
- Addition: 10-18 weeks.
- New construction with RIP multi-unit: 4-8 months.
Oregon CCB licensing:
- Oregon CCB licenses contractors and enforces license law.
- Verify at ccb.oregon.gov.
- See /ask/what-is-oregon-ccb for license class details.
Portland Historic Landmarks:
- Pearl District, Old Town/Chinatown, Alphabet District, and other districts have historic review.
- Portland Historic Landmarks Commission reviews designated properties and districts.
Common Portland homeowner questions under RIP:
- "Can I build a fourplex?" — probably, if zoning is R2.5/R5/R7/R10.
- "Can I build 2 ADUs?" — yes in most R zones.
- "Can I convert my garage to an ADU and build a detached ADU?" — yes, counts as 2 ADUs.
- "What's my maximum house size?" — depends on lot size and RIP cap formula.
RIP's impact nationally:
- RIP was a reference model for Minneapolis, Arlington VA, and similar zoning reforms.
- Combined with Oregon HB 2001 (statewide), Oregon is one of the most permissive US states for middle housing.
AskBaily's Portland contractor pool is familiar with RIP, Oregon HB 2001, and BDS permit process. See /portland for deeper local context.
Sources
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