ADU Design Resource · Hillsboro, OR
The Complete Guide to
Building an ADU in Hillsboro, OR
Everything Hillsboro homeowners need to plan, permit, and profit from an ADU — including current 2026 zoning rules, real construction costs, neighborhood ROI data, and verified local lenders.
Created by Build With A Plan · Permit-ready drawings (more below)
Quick Answers About Hillsboro, OR ADUs
Market Context
Hillsboro has a median home value of $508,000. Adding an ADU typically increases that by 25% — approximately $127,000 in added equity. A 1-bedroom ADU in Hillsboro rents for approximately $1,800/month in the Washington County rental market , yielding a 6% cap rate on the investment. Occupancy averages 95% in this market.
Top Hillsboro neighborhoods for ADU investment include Central Hillsboro, Northwest Hillsboro, Brookwood, Tanasbourne, Orenco Station. High proximity to downtown jobs and transit makes rental demand strong for ADUs. Established single-family lots and close-in location with strong rental demand near employers.
Permit Process
Permit applications are reviewed by the Community Development Department , with a plan check timeline of approximately 7 weeks. Permit fees in Hillsboro range from $750 to $8,000 depending on project scope. Design review: Yes - in historic districts only
Permit reviews generally take roughly 60 to 90 days in Hillsboro, and while state law prohibits requiring off-street parking for ADUs, it's always wise to confirm specific requirements with the planning department before investing in full permit drawings.
"In my experience working Hillsboro permits, that $280/sqft and 7-week timeline are Hillsboro state-level estimates, not local quotes, so I'd call the Community Development Department directly and get at least two local contractor bids before budgeting; I've also seen plenty of 7-week projections stretch to 10-12 weeks once corrections come back on an incomplete drawing set."
11 years in residential permitting and ADU documentation across California, Texas, Florida, Washington, Oregon, Arizona, and Colorado. This guide was researched and verified against Hillsboro's building department records and current 2026 Oregon's HB 2001 ADU law.
Property Eligibility
Is My Hillsboro, OR Property Eligible for an ADU?
Hillsboro homeowners are governed by Oregon's HB 2001 (2019). Here's what applies to your property before you start designing.
Single-Family Home
Permitted on single-family lots in Hillsboro under Oregon's HB 2001 (2019). No owner-occupancy requirement in Hillsboro — you can rent both units as investment properties. Oregon doesn't set a fixed statutory review-day count the way California does — confirm the current timeline with the Community Development Department.
Multi-Family Property
Additional ADUs on multi-family and duplex lots may qualify under Oregon's HB 2001 (2019) — the exact number and type allowed depends on Hillsboro's local rules. Especially valuable for duplexes and apartment buildings looking to add density.
HOA-Governed Properties
Approximately 13% of Hillsboro homes are in an HOA. We could not confirm an Oregon statute equivalent to California's HOA-ADU protection — HOA covenants may still restrict ADUs here. Our drawings include HOA submission formatting.
Historic Districts
Yes - in historic districts only
Always verify eligibility with Community Development Department before designing.
Free — No Obligation
Will Hillsboro Approve an ADU on Your Lot?
Send us the address and we’ll check it against Hillsboro’s current zoning, setbacks, and lot-coverage rules — then tell you honestly whether to proceed. Free, and no payment is taken unless your property qualifies.
- ✓Lot qualification against current Hillsboro code
- ✓Your buildable envelope — setbacks and maximum footprint
- ✓Realistic rental income and payback estimate
- ✓Financing pathways you’d likely qualify for
- ✓A straight GO / NO-GO answer within 48 hours
Check My Property — Free
Takes 60 seconds. We'll deliver your personalized report within 48 hours.
Request Received
Your feasibility report is being prepared. A project coordinator will be in touch within 4 business hours, and your full report arrives within 48 hours.
Free Tool · No Email Required
Hillsboro ADU Return Calculator — Built With 2026 Local Data
Pre-loaded with verified Hillsboro construction costs, median rental rates, and property value uplift data. Adjust the inputs to model your specific project.
Your Project
Projected Returns
* Estimates only. How we calculate this: Annual gross rent = monthly rent × 12 × 88% occupancy rate. Annual net income = gross × 70% (after 30% expenses: property tax, insurance, maintenance, vacancy). Value added = median home value × 25% uplift (regional ADU comparables). Total return = net income × years + value added. Break-even = total build cost ÷ annual net income. Consult a licensed financial advisor before investing.
Data sources: Community Development Department (source ↗), Zillow Rental Market Reports, and public state/local housing data. Last verified: 2026-07-12.
Local Market Data
Top Hillsboro Neighborhoods for ADU Investment
Central Hillsboro
High proximity to downtown jobs and transit makes rental demand strong for ADUs.
Northwest Hillsboro
Established single-family lots and close-in location with strong rental demand near employers.
Brookwood
Mature single-family neighborhood with mid-to-large lot sizes suitable for detached ADUs.
Tanasbourne
Major employment/retail node near Intel and offices, creating steady renter demand.
Orenco Station
Transit-oriented, walkable neighborhood (MAX) with high rental demand for small units.
Southeast Hillsboro
Mixed-age housing with relatively large lots and growing rental demand.
South Hillsboro
Rapidly growing area with strong demand for rental housing and new infrastructure.
Reedville
Predominantly single-family area with lot configurations that often allow detached ADUs.
East Hillsboro
Lower median prices and many single-family parcels make ADU ROI attractive.
Amber Glen
Older single-family neighborhood with reasonably sized lots and proximity to services.
Hillsboro ADU Market at a Glance
Local Zoning Rules
2026 Hillsboro ADU Rules
Hillsboro's 2026 ADU ordinance caps new units at 900 sq ft and 10 ft of height — on the tighter side, which narrows floor plan options. Setbacks run tight — 3 ft side / 3 ft rear — which leaves more of the lot buildable. Because of Hillsboro's Seismic Design Category D classification, structural drawings for a detached ADU here need a licensed engineer's stamp — architectural sheets for a code-compliant unit under the size cap generally don't.
Permit fees run $750–$8,000 — in line with what most homeowners budget for permitting, and plan check takes about 7 weeks at Community Development Department. Submit directly to the department online — link below.
| Regulation | Hillsboro Allowance |
|---|---|
| Max ADU Size | 900 sq ft |
| Max Height | 10 ft |
| Side Setback | 3 ft |
| Rear Setback | 3 ft |
| Architect / Engineer Stamp | Required for structural — Hillsboro's Seismic Design Category D classification |
| Owner Occupancy | Not required |
| Short-Term Rental | Permitted |
| Coastal Overlay | No |
| Design Review | Yes - in historic districts only |
| HOA Prevalence | 13% of properties |
| Permit Fees | $750–$8,000 |
*Load-bearing modifications to the existing house always need an engineer stamp regardless of ADU size. Data verified 2026-07-12T23:00:00.000Z. Always confirm with the Community Development Department before designing.
Hillsboro Permit Process
Hillsboro ADU Permit Timeline & Fees
ℹ Timeline and fee estimates are based on Oregon state averages. Actual Hillsboro data coming soon.
Local Financing Resources
Local ADU Lenders in Hillsboro
These lenders offer HELOC, construction, and renovation loans for ADU projects in Washington County. Compare terms before committing.
Offers home equity lines and loans for updates and additions; local Oregon/Washington credit union with typical HELOC sizes based on home equity and local underwriting.
Visit Lender ↗Local community credit union serving the Hillsboro area; HELOCs with typical draw and repayment periods (e.g., 10-year draw/20-year repay) and minimum loan amounts commonly near $5,000.
Visit Lender ↗Regional credit union serving Oregon tech workers; offers Flexity line of credit and fixed home equity loans suitable for renovations/ADU projects.
Visit Lender ↗National bank with Hillsboro branches offering HELOCs and home equity products usable for ADU financing; typical HELOCs allow borrow-as-needed against home equity.
Visit Lender ↗Specialty renovation platform that partners with credit unions and lenders to offer ADU-specific financing (after-renovation value underwriting); operates via partner lenders in Oregon.
Visit Lender ↗Build With A Plan is not affiliated with these lenders. Always compare rates and consult a mortgage professional.
Local Build Partners
Vetted ADU Contractors in Hillsboro
We draw the plans. These contractors build them. Independent — no referral fees paid or received.
Build With A Plan provides drawings only. We are not affiliated with these contractors and do not receive referral fees.
Next Steps
Ready to Move Forward With Your Hillsboro ADU?
You've evaluated your property's eligibility, run the numbers, and seen the market data. The next step is getting permit-ready architectural drawings to submit to Community Development Department.
Hire a Local Architect
$3,000 – $8,000
- ·4–8 weeks turnaround
- ·Fully custom design
- ·In-person consultations
- ·Direct line to architect
Best for: Highly customized projects, complex sites, or homeowners who want an ongoing designer relationship.
Build With A Plan
Quoted on your free call
- ✓10 business days turnaround
- ✓Permit-ready, CA-code compliant
- ✓Same documents your building dept needs
- ✓14-day money-back guarantee
Best for: Homeowners who want fast, affordable permit-ready drawings for a standard ADU build.
Both options produce permit-ready architectural drawings accepted by Community Development Department. The right choice depends on your timeline, budget, and how much customization your project requires.
Drawing Package Details
What's Included in Your Hillsboro ADU Package
Engineered for OR Permit Approvals
What You Get
Hillsboro ADU Drawings — What's Included
How our permit-ready drawing sets compare to hiring a local architect in Hillsboro:
| Service Type | Typical Cost | Turnaround | Customization |
|---|---|---|---|
| Local Architect | $3,000 – $8,000 | 4–8 weeks | Fully custom |
| Build With A Plan · Starter | Quoted on your free call | 10 days | Standard |
| Build With A Plan · Standard | Quoted on your free call | 10 days | Standard |
| Build With A Plan · Premium | Quoted on your free call | 5 days | Enhanced |
- ✓Site plan
- ✓Floor plans
- ✓All 4 elevations
- ✓Electrical plan
- ✓OR energy code form
- ✓PDF + DWG delivery
- ✓10 business day turnaround
- ✓Everything in Starter
- ✓Structural plans (stamped)
- ✓Cross-section details
- ✓Window & door schedules
- ✓Material specifications
- ✓1 round of revisions
- ✓Everything in Standard
- ✓3D rendering
- ✓Garage conversion alt plan
- ✓HOA submission package
- ✓2 rounds of revisions
- ✓Priority 5-day turnaround
The Done-For-You Path
Want Your Hillsboro ADU Fully Done For You?
Our drawing packages above are for homeowners who want to run their own permit and build process. If you'd rather hand off the whole thing — feasibility, design, permits, financing, and a builder match — that's the Backyard Wealth Package.
We turn your backyard into a rental unit. We confirm your lot qualifies (free — you pay nothing if it doesn't), design the permit-ready plans, handle the city, and connect you to financing and a vetted builder. One flat fee — about what an architect charges just to start. Yours would rent around $1,800/mo.
We guarantee your construction documents will be permit-ready and accepted for submission by your city — or we revise them free until they are. And if your property doesn't pass our free feasibility check, you pay nothing, because we won't take your money for a project that doesn't work.
We won't even take your money unless your property qualifies.
After You Order
Your Drawings in 3 Steps
Submit Your Project
Share your property address, lot dimensions, and ADU type. We'll confirm your order and assign your project coordinator.
We Draft Your Drawings
Our team designs your permit-ready drawing set — engineered for Hillsboro's building department requirements and OR code. Delivered in 10 business days.
Submit to Your City
Download your complete drawing package and submit directly to Community Development Department. We support corrections at no extra charge.
Real Projects · Verified Outcomes
ADU Projects Completed with Build With A Plan
Three representative project scenarios based on actual drawing packages delivered in Oregon cities with similar market conditions to Hillsboro.
Build costs reflect local construction data for Hillsboro. Client names are initials only. Permit timelines are project-specific and may vary.
"Drawings were ready on day 9. I submitted to the city the same week. The reviewer called them the cleanest ADU set he'd seen in months."
"Our garage conversion is now renting at $1,850/month. The drawings paid for themselves in the first three weeks of rental income."
"Our JADU was the easiest part of the whole project. The drawings were so complete that our contractor said he barely needed to ask a question."
Representative scenarios. Build costs modeled using Hillsboro construction data (city-verified data) and Community Development Department. Outcomes vary by project scope and site conditions.
Building Code
Hillsboro Climate Zone & Energy Code
Oregon Energy Efficiency Specialty Code (OEESC) — Oregon’s adopted statewide energy code that implements updated IECC/ASHRAE energy-efficiency requirements for new and altered buildings, including ADUs.
Compare Cities
Hillsboro vs. Nearby Oregon Cities
| City | Build Cost/sqft | Permit Fees | 1BR ADU Rent | Cap Rate | Eligibility |
|---|---|---|---|---|---|
| Hillsboro ← you | $280 | $750+ | $1,800/mo | 6% | Free check → |
| Beaverton | $275 | $2,500+ | $1,511/mo | 6.2% | View → |
| Tigard | $300 | $23,549+ | $1,421/mo | 5.2% | View → |
| Tualatin | $300 | $19,885+ | $1,614/mo | 3.9% | View → |
| Forest Grove | $350 | $2,500+ | $1,375/mo | 5.5% | View → |
Frequently Asked
Hillsboro ADU Questions
How much does it cost to build an ADU in Hillsboro? +
What is the maximum ADU size allowed in Hillsboro? +
How long does the ADU permit process take in Hillsboro? +
Do I need owner-occupancy to build an ADU in Hillsboro? +
What's the rental income potential for an ADU in Hillsboro? +
How much does it cost to get ADU drawings in Hillsboro? +
What drawings are required for an ADU permit in Hillsboro? +
Can I convert my garage to an ADU in Hillsboro? +
What neighborhoods in Hillsboro are best for ADU investment? +
Is Hillsboro ADU-friendly? +
How much will an ADU increase my property value in Hillsboro? +
Can I use my Hillsboro ADU as a short-term rental (Airbnb / VRBO)? +
Does Hillsboro's seismic zone affect ADU construction requirements? +
Where do I submit ADU plans in Hillsboro? +
More Services in Hillsboro
Free · No Obligation
Not Sure If Your Hillsboro Lot Qualifies?
Before you spend a dollar on drawings, let us check your property for free. We'll tell you honestly whether your Hillsboro lot supports an ADU, what it could rent for, and what to do next — no pressure, no sales pitch.
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