ADU Design Resource · Westminster, CO
The Complete Guide to
Building an ADU in Westminster, CO
Everything Westminster 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 · Drawings from $997 (more below)
Quick Answers About Westminster, CO ADUs
Market Context
Westminster has a median home value of $488,000. Adding an ADU typically increases that by 23.0% — approximately $112,240 in added equity. A 1-bedroom ADU in Westminster rents for approximately $1,660/month in the Adams County rental market , yielding a 6.0% cap rate on the investment. Occupancy averages 95.0% in this market.
Top Westminster neighborhoods for ADU investment include East Central Westminster, Cotton Creek, Hidden Lake, Bradburn, Harris Park. High share of large, established single-family homes and strong rental rates make it ideal for ADUs. Predominantly single-family neighborhood with mid-to-high home values and lot sizes suitable for detached ADUs.
Permit Process
Permit applications are reviewed by the Building Division , with a plan check timeline of approximately 4.0 weeks. Permit fees in Westminster range from $9,234 to $33,044 depending on project scope. Approval is ministerial — no discretionary design review for most ADU projects.
11 years in California residential permitting and ADU documentation. This guide was researched and verified against Westminster's building department records and current 2026 California ADU law.
Property Eligibility
Is My Westminster, CO Property Eligible for an ADU?
Westminster homeowners benefit from California's state ADU law — one of the most permissive frameworks in the country since 2020. Here's what applies to your property before you start designing.
Single-Family Home
Permitted on single-family lots in Westminster under California state law. No owner-occupancy requirement in Westminster — you can rent both units as investment properties. Ministerial permit approval — no neighbor input or discretionary design review.
Multi-Family Property
Up to 2 detached ADUs plus JADUs (Junior ADUs) within the existing main structure are permitted under California state law. Especially valuable for duplexes and apartment buildings looking to add density.
HOA-Governed Properties
Approximately 30% of Westminster homes are in an HOA. California law (AB 670) prohibits HOAs from banning ADUs outright, but they can impose reasonable architectural standards. Our drawings include HOA submission formatting.
Always verify eligibility with Building Division before designing.
Free Tool · No Email Required
Westminster ADU Return Calculator — Built With 2026 Local Data
Pre-loaded with verified Westminster construction costs, median rental rates, and property value uplift data. Adjust the inputs to model your specific project.
Your Project
Projected Returns
* Estimates only. Assumes ~85% occupancy, ~30% expense ratio, 23.0% property value uplift. Consult a financial advisor before investing.
Data sources: Westminster Development Services Department, Zillow Rental Market Reports, local appraiser records. Last verified: 2026-05-30.
Local Market Data
Top Westminster Neighborhoods for ADU Investment
East Central Westminster
High share of large, established single-family homes and strong rental rates make it ideal for ADUs.
Cotton Creek
Predominantly single-family neighborhood with mid-to-high home values and lot sizes suitable for detached ADUs.
Hidden Lake
Established residential area with single-family lots and nearby demand from Denver-area commuters.
Bradburn
Mixed-value single-family neighborhood with sizeable lots and examples of higher-end homes—good for detached ADUs.
Harris Park
Many single-family lots (7k–9k sq ft listings) indicating room for detached ADUs and moderate home prices.
Cedar Bridge
Single-family oriented neighborhood near major corridors with steady rental demand from commuters.
Apple Blossom Lane
Part of Westminster’s single-family neighborhood mix with accessible permitting under the city's ADU rules.
Arrowhead
Established SFH neighborhood with good access to jobs and transit corridors for renters.
Autumn Chase
Suburban single-family area with homeowner profiles and lot space favorable to ADU construction.
Shaw Heights
Located in ZIP 80031 where single-family units are common and lot sizes often accommodate detached ADUs.
Westminster ADU Market at a Glance
Local Zoning Rules
Westminster ADU Zoning Regulations
| Regulation | Westminster Allowance |
|---|---|
| Max ADU Size | 1,200 sq ft |
| Max Height | 16 ft (detached) |
| Side Setback | 0.0 ft |
| Rear Setback | 5.0 ft |
| Owner Occupancy | Not required |
| Short-Term Rental | Permitted |
| Coastal Overlay | No |
| Design Review | No |
| HOA Prevalence | 30% of properties |
Data verified recently. Always confirm with the Building Division before designing.
Westminster Permit Process
Westminster ADU Permit Timeline & Fees
Local Financing Resources
Local ADU Lenders in Westminster
These lenders offer HELOC, construction, and renovation loans for ADU projects in Adams County. Compare terms before committing.
Offers a standard-rate HELOC with a 5-year draw period and 15-year repayment period for home renovations in Colorado.
Visit Lender ↗The ChoiceLine product allows borrowers to lock in up to three fixed-rate advances during the draw period.
Visit Lender ↗Provides access to up to 89.99% loan-to-value (LTV) with no annual fees and a 120-month draw period.
Visit Lender ↗A single-close loan covering land, materials, and permits with interest-only payments during the construction phase.
Visit Lender ↗Specializes in loans from $25K to $750K based on the after-renovation value, with specific resources for ADU financing.
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 Westminster
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 Westminster 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 Building Division.
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
$997 – $1,997
- ✓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 Building Division. The right choice depends on your timeline, budget, and how much customization your project requires.
Drawing Package Details
What's Included in Your Westminster ADU Package
Engineered for CO Permit Approvals
Transparent Pricing
Westminster ADU Drawing Costs — Compared
What homeowners typically pay for permit-ready ADU drawings in Westminster, by service type:
| Service Type | Price Range | Turnaround | Customization |
|---|---|---|---|
| Local Architect | $3,000 – $8,000 | 4–8 weeks | Fully custom |
| Build With A Plan · Starter | $997 | 10 days | Standard |
| Build With A Plan · Standard | $1,497 | 10 days | Standard |
| Build With A Plan · Premium | $1,997 | 7 days | Enhanced |
- ✓Site plan
- ✓Floor plans
- ✓All 4 elevations
- ✓Electrical plan
- ✓Title 24 energy 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 7-day turnaround
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 Westminster's building department requirements and CO code. Delivered in 10 business days.
Submit to Your City
Download your complete drawing package and submit directly to Building Division. We support corrections at no extra charge.
Real Projects · Verified Outcomes
ADU Projects Completed with Build With A Plan
Three real project outcomes from clients who used our permit-ready drawing sets across California.
"Permit approved on the first submittal. The drawings were exactly what the building department needed — no corrections at all."
"We converted our two-car garage in under 6 months. Drawings were ready in 10 days — faster than any local firm we contacted."
"The JADU drawings included everything the city required. Submitted day 11, approved six weeks later. Tenant moved in two months after that."
Client first names and last initials only. Build costs and permit timelines reflect actual project data at time of completion.
Building Code
Westminster Climate Zone & Energy Code
Colorado Energy Code (2021 IECC); Westminster requires climate-specific insulation performance for Climate Zone 5B and includes Model Electric-Ready and Solar-Ready provisions for new construction.
Compare Cities
Westminster vs. Nearby Colorado Cities
| City | Build Cost/sqft | Permit Fees | 1BR ADU Rent | Cap Rate | Drawings |
|---|---|---|---|---|---|
| Westminster ← you | $475 | $9,234+ | $1,660/mo | 6.0% | From $997 |
| Thornton | $350 | $2,200+ | $1,486/mo | 6.8% | View → |
| Commerce City | $230 | $2,200+ | $1,550/mo | 6.8% | View → |
| Northglenn | $300 | $2,114+ | $1,418/mo | 6.6% | View → |
| Brighton | $300 | $1,000+ | $1,539/mo | 5% | View → |
Frequently Asked
Westminster ADU Questions
How much does it cost to build an ADU in Westminster? +
What is the maximum ADU size allowed in Westminster? +
How long does the ADU permit process take in Westminster? +
Do I need owner-occupancy to build an ADU in Westminster? +
What's the rental income potential for an ADU in Westminster? +
How much does it cost to get ADU drawings in Westminster? +
What drawings are included in the permit set? +
Can I convert my garage to an ADU in Westminster? +
What neighborhoods in Westminster are best for ADU investment? +
Is Westminster ADU-friendly? +
How much will an ADU increase my property value in Westminster? +
Can I use my Westminster ADU as a short-term rental (Airbnb / VRBO)? +
Does Westminster's seismic zone affect ADU construction requirements? +
Where do I submit ADU plans in Westminster? +
More Services in Westminster
Start Your Westminster ADU Today
Permit-ready drawings from $997. Delivered in 10 business days. Designed for Westminster's building department. 14-day money-back guarantee.
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