Oregon middle housing land division, in brief
A middle housing land division takes a lot that holds middle housing and divides it so that each middle housing unit stands on its own lot. Oregon created the procedure in SB 458 (2021), and it sits in ORS 92.031 [2, 1]. The application carries a middle housing proposal, and the tentative plan is approved when that proposal complies with the Oregon Residential Specialty Code and the applicable rules [1, 4]. Each resulting lot holds exactly one dwelling, the plat carries a notation, and the lots it creates cannot be divided again [1].
Statute numbers in this area have moved, so this page cites each section as it stood when read on October 10, 2026: ORS 92.031 for the division itself, ORS 197A.140 for the expedited procedure, and ORS 227.178 in its 2025 edition for the city's clock [1, 3].
The site plan is where those rules become a drawing: the parent lot, the dwellings on it, and the line that gives each dwelling a lot of its own. Innowave Studio draws that plan for owners and builders preparing a division application. Oregon's wider site plan rules are on the Oregon site plan page, and its ADU rules sit in the state table in ADU laws by state.
What ORS 92.031 asks of the division
| Rule | What the statute provides | What the site plan shows |
|---|---|---|
| Purpose | A middle housing land division lets each middle housing unit sit on its own lot (SB 458, 2021) [2, 1] | The parent lot and every unit on it, with the proposed lot lines |
| Dwellings per lot | Exactly one dwelling on each resulting lot [1] | One dwelling footprint inside each proposed lot |
| Basis for approval | The tentative plan is approved if the application includes a middle housing proposal that complies with the Oregon Residential Specialty Code and the applicable rules [1, 4] | The proposal's footprints as placed on the lot; code compliance of the buildings is shown on the building plans |
| Plat | A notation on the plat, and no further division of the resulting lots [1] | A plan note recording both |
| Procedure | The expedited procedure, now ORS 197A.140, if the applicant requests it [1] | The plan set filed under that procedure |
| Filing | The division can be filed with the building permits [1] | One site plan serving both filings |
| Tentative approval | Void if no final plat follows within 3 years [1] | The tentative plan the final plat is drawn from |
Cities write the procedure into their own codes. Milwaukie, for one, sets it out in Chapter 17.26, Middle Housing and Expedited Land Divisions [4]. The plan is drawn to the code of the city that holds the parcel.
The clock the city reviews it on
An Oregon city decides land use applications against a statutory clock. ORS 227.178(1), in its 2025 edition, sets the "shortest applicable period" from the date the application is deemed complete: 120 days, 100 days for affordable housing under ORS 197A.470, and 63 days for an expedited land division [3]. ORS 92.031 lets a middle housing land division use the expedited procedure, now ORS 197A.140, when the applicant requests it [1].
| Stage | Rule | Source |
|---|---|---|
| Completeness | The city names exactly what is missing within 30 days; the application is void on the 181st day if the applicant was notified and did not respond (227.178(2), (4)) [3] | ORS 227.178 |
| Housing standards | For housing inside an urban growth boundary, the applicant may ask to be reviewed under the standards in effect at the time of the request, and the clocks restart (227.178(3)(a)(B)) [3] | ORS 227.178 |
| Decision standard | Inside an urban growth boundary, housing that complies with clear and objective standards is not denied, with limited exceptions (227.175(4)(b)) [3] | ORS 227.175 |
| Density and height | Where at least 75% of the floor area is housing and the proposal is at or below the allowed density and height, the city may not make approval conditional on reducing either, unless that is needed for health, safety, habitability or a goal-protective measure (227.175(4)(c) to (e)) [3] | ORS 227.175 |
| Extensions | Extensions of the clock total no more than 245 days, plus up to 90 days for mediation (227.178(5), (11)) [3] | ORS 227.178 |
| Filing together | Cities offer a consolidated procedure so all permits for a project can be filed at once (227.175(2)) [3] | ORS 227.175 |
| Written decision | Approval is "based upon and accompanied by a brief statement" of the criteria, facts and justification (227.173(3)) [3] | ORS 227.173 |
| Missed deadline | The city refunds the greater of the unexpended fees or 50% (227.178(8)) [3] | ORS 227.178 |
| Local appeal | At least 12 days from mailing for a decision made without a hearing (227.175(10)(a)(C)) [3] | ORS 227.175 |
| State appeal | Final decisions go to the Land Use Board of Appeals under ORS 197.830 to 197.845 (227.180(2)) [3] | ORS 227.180 |
The completeness letter is the stage the site plan most affects, so the plan is drawn to the city's checklist item by item, with each dimensional standard set beside the drawn value.
What the site plan for the division shows
The plan for a middle housing land division is a plan of one parent lot, drawn to show the division the statute allows:
- The parent lot. Its boundary and dimensions, taken from the survey or recorded plat the owner supplies.
- Every dwelling. Each middle housing unit, built or proposed, with its footprint and its distances to the existing and proposed lot lines.
- The proposed lot lines. One dwelling inside each resulting lot, the rule ORS 92.031 sets [1].
- Wetlands. Statewide Wetlands Inventory areas on or near the lot. For new structures in those areas, the city notifies the Department of State Lands within five working days of accepting a complete application, and if DSL is silent for 30 days it may approve with notice that state or federal permits may be required (ORS 227.350) [3].
- A site data table. The parent lot area, the area of each resulting lot, one dwelling per lot, and each local dimensional standard against its drawn value.
- Plan notes. The plat notation and the bar on further division [1], and the residential code the proposal is checked against: the 2023 Oregon Residential Specialty Code, mandatory since April 1, 2024 [5].
Plans are preliminary, and engineering is by your engineer of record. Grading, drainage and utility design stay with that engineer, and the building plans show the code compliance of each dwelling.
Who decides, and the ADU next door
Inside city limits the city decides under ORS 227, and within six miles outside them a plat needs city approval unless an urban growth boundary management agreement or a county subdivision ordinance assigns it to the county (ORS 227.110) [3]. The site plan names the deciding body in its title block.
An accessory dwelling unit beside a detached single-unit dwelling is a different path, under ORS 197A.425 as read October 10, 2026, which keeps owner occupancy out of the local rules a city may adopt, vacation occupancies excepted [6]. The rest of Oregon's ADU row is in ADU laws by state. What city ADU checklists ask a plan to show is in ADU site plan requirements.
How to order a middle housing land division site plan
- Open start a project and choose Residential: lot split or middle housing division as the project type, with single-family and townhome as the asset class.
- Give the city or county and Oregon as the location, so the plan is drawn to that city's chapter.
- Under program and stage, give the number of dwellings, whether they are built or proposed, and whether you will request the expedited procedure.
- Attach one file, the most useful you have: the survey or recorded plat of the parent lot, or a sketch of the building footprints with measurements. If the city has sent an application checklist or completeness letter, name it under program and stage.
The studio reads the brief, checks the city's code and replies by email to scope the plan. Developers dividing more than one parent lot should start from the single-family and townhome site plan hub or a preliminary site plan. Other permit plans are listed on permit site plans. To order the site plan for your division, start a project and choose Residential: lot split or middle housing division.
Frequently asked questions
What is a middle housing land division in Oregon?
Can a lot from a middle housing land division be split again?
No. ORS 92.031 bars any further division of the resulting lots and requires a notation on the plat [1].
How long does a tentative approval last?
It is void if no final plat follows within 3 years [1].
How fast must an Oregon city decide an expedited land division?
Can the division be filed with the building permits?
What if the application is incomplete?
The city has 30 days to name exactly what is missing, and an application is void on the 181st day if the applicant was notified and did not respond (ORS 227.178(2), (4)) [3].
Sources
- 1)Oregon Revised Statutes Chapter 92 (ORS 92.031, middle housing land division), Oregon State Legislature. Accessed 2026-10-10.
- 2)Housing Choice: middle housing (SB 458), Oregon Department of Land Conservation and Development. Accessed 2026-10-10.
- 3)Oregon Revised Statutes Chapter 227, Cities: Planning; Zoning (2025 edition), Oregon State Legislature. Accessed 2026-10-10.
- 4)Chapter 17.26, Middle Housing and Expedited Land Divisions, City of Milwaukie, Oregon (code via eCode360). Accessed 2026-10-10.
- 5)Adopted codes online, Oregon Building Codes Division. Accessed 2026-10-10.
- 6)Oregon Revised Statutes Chapter 197A (ORS 197A.425, accessory dwelling units), Oregon State Legislature. Accessed 2026-10-10.
How these sources were chosen and when the page is reviewed: how we research.