Pierce County is undergoing a quiet housing revolution—and it’s happening in backyards. Recent changes to Washington State and county zoning laws have opened the door for homeowners and investors to build more housing on existing lots. Specifically, Accessory Dwelling Units (ADUs) and Detached Accessory Dwelling Units (DADUs) are now easier to build, larger in size, and more attractive as long-term investment opportunities.
Whether you’re a homeowner looking to maximize property value or an investor seeking cash flow, the 2025 updates make now the perfect time to explore building an ADU or DADU in Pierce County.
1. Overview of Code Changes in Pierce County
In response to Washington’s House Bill 1337 and state-level efforts to increase housing density, Pierce County adopted significant code revisions in mid-2025. These align with the Growth Management Act and the state’s Vision 2050 housing goals.
Key changes include:
-
Up to two ADUs per lot are now permitted in urban growth areas (can be any combination of attached or detached units).
-
Increased unit size: ADUs may now be up to 1,000 square feet in urban areas and 1,250 square feet in rural areas.
-
No parking requirement if the property is within half a mile of a major transit stop.
-
Simplified design requirements: ADUs cannot be subject to stricter design standards than the primary dwelling.
-
Impact fees are capped at 50% of what’s charged for the main house, lowering upfront costs.
-
Faster permit approval processes and pre-approved building plans are being implemented by Pierce County to streamline development.
These changes are designed to promote housing diversity, increase supply, and help communities grow without dramatically altering their character.
2. Why This Matters: Investment and Value Opportunities
The new rules make ADU and DADU construction significantly more accessible and financially viable. For property owners, this opens the door to a wide range of benefits:
Rental Income Potential
Build a secondary or detached unit to generate monthly cash flow. With high rental demand in Pierce County, especially in Tacoma, Puyallup, and University Place, ADUs make excellent long-term investments.
Multi-Generational Living
Create a private space for aging parents, adult children, or extended family—offering both independence and proximity.
Property Value Appreciation
An ADU or DADU increases the total livable space on your lot, which can significantly boost resale value or allow for a future condominium-style subdivision, depending on local zoning.
Affordability for Homeowners
With capped fees, no parking requirements, and more flexible permitting, it’s now less expensive and faster to build an ADU than ever before.
3. Common Uses for ADUs and DADUs
-
Rental unit (long-term or short-term)
-
In-law suite
-
Guest house
-
Home office or studio
-
Aging-in-place unit for elderly relatives
-
Student or workforce housing
4. The Construction Process for ADUs and DADUs
Building an ADU or DADU is very similar to new home construction, but on a smaller scale. Here’s what the process typically looks like when working with a professional builder like Pacific Coast Renovations:
Step 1: Site Evaluation & Feasibility
We assess your property to determine what’s possible under the new Pierce County zoning laws. This includes:
-
Lot size and layout
-
Access and setbacks
-
Utility capacity (water, sewer, electric)
-
Slope, trees, and easements
Step 2: Design & Planning
Once the project is deemed feasible, we move into design:
-
Custom plans or pre-approved Pierce County models
-
Placement planning for privacy and access
-
Architectural drawings
-
Optional garage conversions or over-garage units
We also help homeowners plan for long-term use: whether you want rental income, a future sale, or multi-generational housing flexibility.
Step 3: Permitting
Pacific Coast Renovations handles the full permitting process, including:
-
Submitting plans to Pierce County
-
Responding to zoning or building department feedback
-
Securing approvals for utilities and any environmental considerations
Permitting timelines have recently been reduced thanks to new state requirements. Most permits are now processed in 4–8 weeks, depending on complexity.
Step 4: Site Preparation
We prepare the site by:
-
Clearing vegetation
-
Installing temporary access paths
-
Running utility trenching for water, sewer, electrical, and communications
If the project includes converting a garage or modifying an existing structure, we also prep the interior framing and systems.
Step 5: Foundation and Framing
We pour a concrete slab or set foundation footings. Then framing begins:
-
Floor, wall, and roof structures
-
Window and door installation
-
Roofing and siding
This is typically the fastest phase and shows the most visual progress.
Step 6: Mechanical, Electrical, and Plumbing (MEP)
We rough-in:
-
Electrical wiring
-
Plumbing supply and drainage
-
HVAC or mini-split systems
Inspections are scheduled and passed before insulation and drywall can begin.
Step 7: Interior Finishes
This is where your ADU takes shape:
-
Insulation, drywall, and paint
-
Cabinetry, countertops, flooring
-
Fixtures, trim, and appliances
We tailor the finishes to match your main home or create a modern, marketable design for renters.
Step 8: Final Inspection & Move-In
Once final inspections are passed, the unit is ready for use—whether that means listing it for rent, moving in family, or just enjoying the extra space.
5. What to Expect for Timeline and Budget
Typical Timeline:
From planning to move-in, a full DADU build usually takes 4 to 6 months, depending on permitting and weather. Garage conversions or internal ADUs may take less time.
Budget Range:
-
Attached ADUs: $100,000–$150,000+
-
Detached ADUs (DADUs): $150,000–$300,000+, depending on size, finishes, and site prep
We can help you explore financing options, including HELOCs, construction loans, or cash-out refinancing.
6. Why Homeowners in Pierce County Should Act Now
The 2025 zoning changes make this the most favorable time in decades to invest in an ADU or DADU in Pierce County. By acting now, you can:
-
Capitalize on rising rental demand
-
Increase your home’s value before the market catches up
-
Build with fewer fees and delays
-
Get ahead of potential changes or restrictions that may be reintroduced as demand surges
Final Thoughts
ADUs and DADUs are no longer a fringe housing option—they are a practical, profitable, and popular solution to Washington’s growing housing needs. Whether you’re looking to create a rental unit, add family space, or future-proof your home investment, the time to start is now.
At Pacific Coast Renovations, we specialize in helping homeowners navigate the design, permitting, and construction of ADUs and DADUs throughout Pierce County. With over 20 years of local construction experience, we can make the process smooth, transparent, and fully tailored to your property and goals.
Ready to explore what’s possible on your lot?
Contact us today for a free consultation and property evaluation.
