Cities · Pierce County

Can I build a backyard home in Pierce County (unincorporated)?

Since 2023, Washington law lets most city lots hold up to two more homes. Pierce County (unincorporated) 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 Pierce County (unincorporated) 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 Pierce County (unincorporated) allows.

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

ADUs per lotUrban growth area: 2 per lot of record. Outside the UGA: 1Full wording

Urban growth area: 2 per lot of record. Outside the UGA: 1.

Max size1,000 sq ft in the UGA; 1,250 outsideFull wording

1,000 sq ft inside the UGA; 1,250 sq ft outside, including basements and attics and excluding garages

Max heightNot above the main house (at least 24 ft must be allowed)Full wording

Not above the principal dwelling, except one additional story over a detached garage; a minimum of 24 ft must be allowed unless the principal dwelling is shorter

Front setbackNo closer than the principal dwellingFull wording

No closer than the principal dwelling

Side setback5 ft inside the UGAFull wording

5 ft inside the UGA

Rear setback5 ft (2 ft at an alley)Full wording

5 ft inside the UGA; 2 ft at an alley

Lot coverageNo coverage row in the current tables — confirm with the countyFull wording

No lot-coverage or impervious row in the current zoning tables — the SF/MSF zones are now SR, RR and MH (Ord. 2025-516s / 2026-523s) and Tables 18A.15.040-1/-2/-3 cover setbacks and height only (SR: front 25 ft arterial / 15 ft other, interior 5 ft, rear 10 ft; 35 ft). Impervious limits may sit in Title 18J / the stormwater manual — UNVERIFIED — confirm with city

ParkingNone near major transit; otherwise per PCC 18A.35.040Full wording

None within 1/2 mile of a major transit stop; otherwise per PCC 18A.35.040

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

Lot of record

Do you have to live there?

Not stated in PCC 18A.37.120; prohibited as a requirement by state law inside the UGA

Can it be sold on its own?

Permitted by state law

Pre-approved plans

None found

How long the city takes

No permit-timelines page. PPW's 'Permitting with Pierce County' deck (Dec. 2024) gives the SB 5290 tiers — Tier 1: 65-day approval, 15-day review cycles; Tier 2: 100 days / 30-day cycles; Tier 3: 170 days / 60-day cycles — without saying which tier a residential building permit falls in. Ask the Development Center (response within 24–48 hours by web form)

Impact fees

ADU impact fees are 50% of the principal unit's: traffic (fee schedule effective Feb. 1, 2026) ADU $3,001 in TSA A/B, $4,875 TSA C, $1,233 TSA D (single-family $5,902 / $9,650 / $2,367) plus a $100 administrative fee per unit; parks 'calculated at half that of the primary dwelling unit' (PCC 4A.20.030); school and park fees are bedroom-based since Ord. O2026-531 (July 2026) with ADUs at 50% of the bedroom-based fee

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 Pierce County (unincorporated) 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.

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Sources

Where this page comes from.

Read from the Pierce County (unincorporated) 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 county.

Nearby

Other places in Pierce County.

Tacoma 1,000 sq ft of living area All cities →

Find out what your property could become.

Type your address. Within a few hours: what Pierce County (unincorporated) allows, what could fit, and a planning cost range. Free, no obligation.

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