Tacoma DADUs & Backyard Cottages
Detached accessory dwelling units — design, permits, build. We handle the full HB 1337 path.
We've been remodeling homes in Tacoma and Pierce County for over 10 years. When Washington passed HB 1337 in 2023 and Pierce County followed with Ordinance 2025-516s, we started getting calls from homeowners who'd heard the rules changed but didn't know what that meant for their property. We built our own DADU — a garage conversion on a Tacoma lot — so we'd know every step of that path firsthand before we walked a client through it.
That project is in our portfolio. You can see the foundation work, the framing, the finished interior. We're not describing something we've read about; we're describing something we've done. A DADU involves permits, structural engineering, site work, mechanical rough-ins, and finish carpentry — the same skill set we've used on every remodel we've built. We handle the design, we pull the permits, we manage the build. One point of contact, start to keys.
ADU or DADU — what's the difference?
A living unit added to the side or back of your main home, sharing at least one wall. Shares the foundation line and often the utility connections. Good for smaller lots or where setbacks limit a separate structure.
A fully separate structure in the backyard or elsewhere on the lot — sometimes called a backyard cottage. Its own foundation, its own roof, its own address. This is what most people picture when they hear "ADU."
An existing basement or lower level converted into a separate dwelling with its own entrance, kitchen, and bath. Lower build cost; the structure is already there.
An attached or detached garage renovated into living space. HB 1337 requires cities and counties to allow this even if the existing footprint doesn't meet current setback rules.
The Rules
HB 1337 + Pierce County — what changed
Washington's HB 1337 — signed into law in 2023 and codified at RCW 36.70A.680, 36.70A.681, and 36.70A.696 — rewrote the rules for accessory dwelling units across every Growth Management Act jurisdiction in the state. That includes all of Pierce County, the City of Tacoma, and every municipality within them. Before HB 1337, local zoning could require owner-occupancy, cap unit size far below 1,000 square feet, and block garage conversions outright. Those restrictions are now preempted by state law. Here is what HB 1337 requires as of 2026:
- Two ADUs are allowed on any lot inside the Urban Growth Area — attached, detached, or one of each.
- No owner-occupancy requirement. You are not required to live on the property.
- Minimum 1,000 sqft allowed. Cities cannot set a lower maximum size than 1,000 square feet of floor area.
- Maximum height of 24 feet. Local rules cannot be more restrictive than what applies to the principal unit.
- Impact fees capped at 50% of what would be charged on the principal dwelling unit.
- No ADU-specific design review, aesthetic standards, or off-street parking requirements (within half a mile of major transit, parking cannot be required at all).
- No required public street improvements just because you're adding an ADU.
- CC&Rs recorded after July 23, 2023, cannot prohibit ADUs. Earlier CC&Rs that attempt to restrict ADUs may also be superseded where they conflict with state law.
- Conversions of existing structures — detached garages, sheds, carports — must be allowed even if the structure sits closer to the property line than current setback rules would permit for new construction.
- ADUs can be sold as condominiums, separately from the main house, opening the door to a different financial model entirely.
Pierce County codified these standards through Ordinance 2025-516s (PCC 18A.37.120), adopted in late 2025. The ordinance sets rear setbacks as low as 2 feet against alleys and 5 feet side and rear in the UGA — practical standards that make many infill sites workable. Permit timelines for DADUs have improved sharply under the new framework. Most Pierce County and City of Tacoma DADU applications are reviewed in 4–8 weeks — a fraction of the 4–6 months that was common before HB 1337 required jurisdictions to streamline their processes.
References: RCW 36.70A.680/681/696 · Pierce County Ordinance 2025-516s (PCC 18A.37.120) · City of Tacoma "Home in Tacoma" implementation, effective Feb 2025.
What does a DADU cost in Tacoma?
The cost of a DADU in Pierce County depends on site conditions, finishes, and whether you're building from scratch or converting an existing structure. What follows are honest ranges based on current material and labor costs in the Tacoma market — not minimum bids designed to get you in the door. Seattle DADUs typically run $350–$650 per square foot; Tacoma and Pierce County come in meaningfully lower, generally $280–$450 per square foot.
Pierce County DADUs typically run 10–20% below Seattle pricing. Get a project-specific estimate using the calculator below.
What can a DADU do for your home?
Rental income
$18K–$24K / yr
Tacoma one-bedroom rents have risen steadily — most DADUs in residential neighborhoods command $1,500–$2,000 per month. At the low end of that range, a $250,000 DADU pays for itself in under 14 years before factoring in property value appreciation.
Property value
+10–20%
A permitted DADU adds roughly 10–20% to the assessed resale value of the underlying property in this market. A home worth $600,000 today could appraise at $660,000–$720,000 with a built and permitted DADU on the lot — before a single month of rent is collected.
Family flex
Multi-gen
Not every DADU is about rental income. Some homeowners build for a parent who wants to stay close but needs independence. Others build for an adult child who can't afford Tacoma rent on their own. A DADU gives you options that a single-family home doesn't.
Stock plans
Pre-engineered to ship faster
Two PeakCraft signature plans, refined for Tacoma lots and Pierce County code. Faster permitting, fewer surprises, lower design cost.
How a DADU comes together
Site walk
Free · 1 hrWe meet at your property, talk through your goals and constraints, and sketch what fits.
Concept design
1–2 weeksLayout, exterior look, and rough budget. You see options before any permit fees.
Permit submittal
1 week prepWe prepare the full submittal package — plans, structural, energy, site.
Permit issued
4–8 weeksHB 1337 has cut DADU review times sharply. We track every comment until issuance.
Build
4–6 monthsFoundation through finish. Weekly updates with photos and milestones.
Final walkthrough
Move-in weekWalk every room. Punch list signed off. Keys handed over.
Quick estimate
Ballpark your DADU in two minutes
No contact info needed to see the number — we ask at the end if you want us to follow up.
Prefer the full estimate page? Open the standalone calculator →
Step 1 of 4 — Project basics
Tell us about the project
Just a few questions to ballpark your budget.
Pick one to continue.
Enter a number between 10 and 10,000.
Step 2 of 4 — Finish quality
Pick a finish level
Sets the base cost per square foot.
Basic
Builder-grade finishes, stock cabinets, laminate counters.
Mid-range
Semi-custom cabinets, quartz counters, quality fixtures.
Luxury
Custom cabinetry, stone counters, premium appliances.
Pick a finish level to continue.
Step 3 of 4 — Scope add-ons
Anything else in scope?
Check whatever applies. We'll add typical costs.
Step 4 of 4 — Almost done
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We'll email a copy and follow up within 24 hours.
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Frequently asked questions
How much does a DADU cost in Tacoma?+
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Do I need to live on the property?+
Can I rent both my house AND the DADU?+
Can I convert my detached garage into a DADU?+
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Ready to start your project?
Free consultations across Tacoma, Lakewood, Puyallup, Gig Harbor and University Place. We respond within 1–2 business days.