Cities · King County

Can I build a backyard home in Shoreline?

Since 2023, Washington law lets most city lots hold up to two more homes. Shoreline writes its own rules on top. Here’s what the code says, in plain English — and a free report on what may fit on your lot.

Read from the Shoreline code on October 9, 2026 · confidence medium · a summary, not legal advice. Rules change; the report re-reads them for your parcel.

The short version

What Shoreline allows.

The headline standards. Open any card for the full wording and the code section.

ADUs per lot2 per lot, not subject to base densityFull wording

2 per lot, not subject to base density

Max size1,200 sq ftFull wording

1,200 sq ft — 'Accessory dwelling units shall not be larger than 1,200 square feet'; an interior ADU 'may be larger than 1,200 square feet where the unit is located on a separate floor' and shares the primary roof (SMC 20.40.210.C, Ord. 1047, 2025)

Max heightZone base height, 23-35 ft in residential zonesFull wording

Zone base height, 23-35 ft in residential zones; no DADU-specific limit

Front setbackThe zone’s setbacksFull wording

Zone setbacks

Side setbackThe zone’s setbacksFull wording

Zone setbacks

Rear setbackThe zone’s setbacks; 0 ft at an alleyFull wording

Zone setbacks; a DADU may sit 0 ft from an alley

Lot coverageHardscape 50% in NR1–NR3 (more with 2+ units)Full wording

No building-coverage row; maximum hardscape 50% in NR3, NR2 and NR1 (the former R-4/R-6/R-8 names no longer appear in Table 20.50.020(1)); with 2+ units: NR3 50%, NR2 60%, NR1 75% (fn 6); +10% where a required shared drive needs it (fn 23(b)). Minimum lot area NR3 7,200 / NR2 5,000 / NR1 2,500 sq ft; base height NR3 23 ft (28 pitched), NR2 30 (35), NR1 35 (40); a DADU side/rear setback may be zero at an alley (fn 25)

Parking1 space, waived within 1/2 mile of a major or frequent transit stopFull wording

1 space, waived within 1/2 mile of a major or frequent transit stop

Where a city figure reads stricter than the state floor (RCW 36.70A.681), the floor may control — the report flags it for your parcel.

The rest

Living there, selling it, plans, time and fees.

Each answer is the code’s own wording, with the section it comes from. “Not published yet” means the city hasn’t posted a figure — the report asks the city, not the internet.

Are backyard homes allowed?

Yes

Minimum lot size

Zone minimum applies

Do you have to live there?

No — deleted

Can it be sold on its own?

Yes — the prohibition on segregating ownership was deleted

Pre-approved plans

None found

How long the city takes

Target 65 days for administrative decisions such as building permits (100 with public notice, 170 with a hearing); the clock pauses while corrections are out. 2024 actuals: single-family simple average 32 days (median 22, 83% within target); single-family complex average 109 (median 82, 43% within target); residential remodel average 37. No ADU row (https://www.shorelinewa.gov/government/departments/planning-community-development/for-residents-permits-development-information)

Impact fees

Parks: ADU pays 50% of the principal unit's park impact fee or the square-footage rate, whichever is less (Ord. 1013, effective July 1, 2025; SMC 3.70). Transportation (SMC 3.80): rates by council resolution — the 2023 schedule (Ord. 1002) listed ADUs under ITE 220 low-rise multifamily at $8,590.50 per unit; the current schedule page could not be read — confirm the 2026 figure and the 50% cap with the city. City ADU handout (rev. 3/2025): impact fees apply to ADUs 'which have reduced fee amounts'. No school impact fee in SMC Title 3

Your lot

The code is half the answer. Your parcel is the other half.

Lines and easements

Where the lot lines really are, which setbacks apply on each side, and whether a utility or access easement takes the corner you had in mind.

Critical areas and slope

Steep slopes, wetlands and streams come with buffers that no citywide number shows. The report reads the county’s maps for your parcel.

Sewer, septic, water, trees

Whether sewer reaches the lot or it’s on septic, where the water service is, and which trees a city protects — the things that decide where a unit can actually go.

Free, within a few hours, no obligation.
What Shoreline allows, what could fit on your lot, and a planning cost range. If something won’t fit, the report says so — and shows what might.

Check my property, free →

Sources

Where this page comes from.

Read from the Shoreline municipal code and the city’s own pages on October 9, 2026. The same table feeds the HousUp report, so the report and this page never disagree. Cities amend their codes; before you design anything, confirm the current wording with the city.

Nearby

Other places in King County.

Bellevue 1,200 sq ft Kenmore Attached 1,000 sq ft Kirkland 1,200 sq ft gross floor area Redmond 1,000 sq ft Renton 1,000 sq ft Seattle 1,000 sq ft All cities →

Find out what your property could become.

Type your address. Within a few hours: what Shoreline allows, what could fit, and a planning cost range. Free, no obligation.

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