Residential drafting in Lake Oswego, Oregon
Lake Oswego is lakefront, hillside, and heavily treed, and the housing runs from early cottages through a substantial midcentury body of work from roughly 1935 to 1965, into lakefront custom homes and later upscale subdivisions.
Midcentury houses here bring low slope roofs, large glazing areas, post and beam elements, masonry fireplaces, and structural grids that do not follow later convention. An addition has to read those before it can tie into them.
Trees are a first order constraint rather than landscaping. The city's tree code applies to construction, and a footprint chosen before the tree survey usually has to move. Slope, retaining, drainage, and construction access on narrow streets shape the project alongside it.
Lakefront and sensitive lands parcels add setbacks and review that have nothing to do with ordinary zoning geometry, so the recorded plat and the overlay map matter as much as the lot dimensions.
ADU standards
Setback, size, and parking rules for an accessory dwelling unit in Lake Oswego.
| Maximum size | 800 sq ft of gross floor area. No percentage of the house test (LOC 50.03.004.1.b.vi) |
|---|---|
| Conversion allowance | When converting part of a dwelling that existed on August 2, 2018, up to 200 sq ft of circulation, chimney, and mechanical space is excluded from the calculation (LOC 50.03.004.1.b.vi) |
| Setbacks, height, and lot coverage | The underlying zoning district standard (LOC 50.03.004.1.b.vi) |
| Privacy, within 10 ft of a line | The entrance must sit at least 10 ft from any property line, a 6 ft sight obscuring wood fence is required, and window panes must sit at least 72 inches above the finished floor (LOC 50.03.004.1.b.vi) |
| Internal conversion entrance | The new entrance may not be placed on the front facade (LOC 50.03.004.1.b.vi) |
| How many | One additional unit alongside a single family dwelling (LOC 50.03.004.1.b.vi) |
| Parking | None required |
The privacy rules are the most specific thing on this page and they shape the elevations directly. If a detached unit sits within 10 feet of a property line, its entrance has to be at least 10 feet from that line, a six foot sight obscuring wood fence is required along it, and any window in the facing wall has to sit at least 72 inches above the finished floor (LOC 50.03.004.1.b.vi). That last one is a design constraint, not a detail: it rules out ordinary windows on that wall.
The 200 square foot conversion allowance is narrower than it sounds. It applies only when converting part of a dwelling that existed on August 2, 2018, and only to circulation space, chimneys, and mechanical areas. It is not a bonus 200 square feet of living space.
For an internal conversion, the new entrance cannot go on the front facade.
Lake Oswego waives its system development charges for a qualifying unit permitted on or after February 1, 2022, in exchange for a recorded covenant barring rental of under 31 days anywhere on the property for ten years (LOC 39.06.105(5)). Building permit and water service fees are not system development charges and are not waived.
A pre-application conference is required for anything other than a straight internal conversion, so it belongs in the schedule from the start.
Planning office: Lake Oswego Planning and Building Services
Sources: Lake Oswego Community Development Code 50.03.004. Lake Oswego Code 39.06.105. ORS 197A.425. Last checked August 2026.
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