Middle Housing in Portland: Duplex to Sixplex, Cottage Clusters and Land Divisions

What a lot can carry

Under the Residential Infill Project, single-dwelling zones allow these options (not in the RF zone or the "z" constrained-sites overlay):

• House, house + 1 ADU, or house + 2 ADUs

• Duplex, or duplex + 1 detached ADU

• Triplex or fourplex

• 4 to 6 units when 50 percent are affordable at 60 percent of median family income (FAR up to 1.2:1, height up to 35 ft)

• Cottage cluster of 3 to 16 detached units (no ADUs)

Lots on unmaintained streets are limited to 2 units.

Minimum lot sizes

For a triplex, fourplex, house + 2 ADUs or duplex + ADU:

• R2.5: 1,500 sq ft

• R5: 3,000 sq ft

• R7: 4,200 sq ft

• R10: 6,000 sq ft

• R20: 12,000 sq ft

Cottage clusters need 5,000 sq ft in R2.5 and R5, and 7,000 sq ft in R7 and R10. They are not allowed in R20.

How big

Floor area ratio (FAR) rises with the number of units. Maximum FAR in R20/R10 and R7, then R5, then R2.5:

• 1 unit: 0.4, 0.5, 0.7

• 2 units: 0.5, 0.6, 0.8

• 3 units: 0.6, 0.7, 0.9

• 4 or more units: 0.7, 0.8, 1:1

A bonus applies for affordable units or for keeping an existing house at least 5 years old. Cottage clusters are exempt from base-zone FAR.

Other rules that shape the design

• Parking: no off-street parking is required in single-dwelling zones.

• Visitability: with three or more units on a site, one building needs a no-step entrance, a bathroom and living area on that level, and 32-inch interior doors. Affordable 4 to 6 unit projects need at least 2 visitable units; cottage clusters at least 33 percent.

• Two units required: lots over 5,000 sq ft in R2.5, 10,000 sq ft in R5 or 14,000 sq ft in R7 must have at least 2 units.

Selling units separately: middle housing land divisions

A middle housing land division (MHLD) puts each unit of a duplex, triplex, fourplex or cottage cluster on its own lot. It is reviewed as an expedited land division: staff decision, no public notice, appeal only by the applicant.

• Completeness check within 21 days; decision within 63 days of a complete application.

• One unit per lot, no ADUs, and the new lots cannot be divided again.

• Construction must be underway with inspections passed before the final plat, which is due within 3 years.

• Vacant lots, a house + ADU, and buildings under the commercial code do not qualify.

Building code and permits

For MHLD sites the City requires the Oregon Residential Specialty Code. Attached units are built as townhouses, each with its own permit; triplexes, fourplexes and cottage clusters use a residential batch permit plus a site development permit. Stacked units are apartments under the Oregon Structural Specialty Code, a heavier permit path.

Fees and incentives

New dwelling units with permits issued August 15, 2025 through September 30, 2028 are exempt from sewer, water, parks and transportation system development charges (SDCs), if the foundation inspection passes within 12 months of issuance. ADUs are excluded from that program but can use a separate SDC waiver with a 10-year covenant against short-term rental. Permit fees and the construction excise tax still apply.

Common questions

Can I build a fourplex on an R5 lot?

Yes, on a lot of at least 3,000 sq ft outside the "z" overlay, at a maximum FAR of 0.8:1, with one visitable building.

Can I build six units?

Yes, if half the units are affordable at 60 percent of median family income, within 1.2:1 FAR and 35 ft.

Do I need parking?

No. Portland removed off-street parking requirements in single-dwelling zones.

Can each unit be sold?

Yes, through a middle housing land division, decided within 63 days of a complete application.

How SASHKOV handles it

• Checks the lot first: zone, lot size, critical areas, trees, utilities and access, in writing.

• Runs a yield study: how many units the lot can carry, at what floor area, and whether an MHLD fits.

• Brings in the surveyor, structural engineer or other licensed professional the project needs, under one contract.

• Prepares the permit set, answers corrections and coordinates inspections through issuance.

Where a building requires a licensed architect or engineer of record, SASHKOV brings them into the contract.

More on Portland: the City of Portland breakdown.