Permitting An ADU In Arvada: Steps, Fees And Timing

Thinking about adding an accessory dwelling unit to your Arvada property? An ADU can create flexibility for guests or long-term rental income, but the path from idea to permit has specific steps, fees, and timing. This guide lays out what applies in the City of Arvada, what you will submit, how fees work, and how long it really takes. You will leave with a clear, practical plan. Let’s dive in.

Start with your jurisdiction

If your address is inside the City of Arvada, the city’s ADU rules and permit process apply. The City’s ADU page is your primary resource for definitions, size limits, submittal lists, and timelines. Review the overview on Arvada’s Accessory Dwelling Units page to confirm current standards and checklists. City of Arvada ADU overview

If your property is in unincorporated Jefferson County, different rules and reviews apply. Jefferson County has its own ADU guidance and permit channels. Jefferson County ADU guidance

Colorado’s ADU law requires subject cities like Arvada to allow at least one ADU where detached single-unit homes are allowed and limits certain local restrictions. This is why ADUs are broadly allowed in Arvada’s residential zones. Colorado DOLA ADU summary

ADU types and size limits

Arvada recognizes two ADU types:

• Type A: Detached ADU. A separate building on the lot.
• Type B: Interior or attached ADU. Within or attached to the main home.

Key size rules to screen your feasibility:

• For new construction or additions, the ADU cannot exceed 40% of the primary dwelling’s living area. In addition, the lot-size cap applies:
  • Lots 6,000 sq ft or smaller: 600 sq ft max
  • Greater than 6,000 to 12,499 sq ft: 850 sq ft max
  • 12,500 sq ft to 1 acre: 1,000 sq ft max
  • Larger than 1 acre: 1,200 sq ft max
• Type B ADUs built entirely inside the existing footprint are exempt from the lot-size cap and are limited to 50% of the principal dwelling’s floor area.
• Setbacks and site rules vary by zone. On corner lots, detached ADUs must sit at least 10 feet behind the main home’s façade along both streets. Confirm zone standards and setbacks on the City’s ADU page. Arvada ADU standards and submittals

Permitting steps in Arvada

1. Confirm city vs county and zoning. Verify you are inside Arvada city limits. ADUs are allowed in residential zones where a detached single-family home exists.
2. Have a planner conversation. Ask about easements, floodplain, lot coverage, or septic and well considerations early.
3. Design and engineering. Prepare plans. Detached ADUs typically need stamped structural and foundation plans, a soils report, truss specs, Manual J/D/S, utility and grading plans, and energy compliance documentation if applicable. Interior ADUs need floor plans and 1-hour fire separation details, plus any expansion documents.
4. Hire licensed contractors and submit. Arvada issues ADU permits to licensed contractors with the right classification. Submit through eTRAKiT. The portal includes a fee estimator. Arvada eTRAKiT fee estimator and portal
5. Plan review. Target review times for complete submittals are about 3 weeks for Type A and 1 to 2 weeks for Type B. Incomplete plans cause delays. Arvada ADU timelines
6. Pay permit fees and capacity charges. Once approved, you will pay building permit fees and any system development charges. If your ADU adds plumbing fixtures, Metro Water Recovery sewer capacity fees must be paid before the certificate of occupancy.
7. Build with inspections. Expect inspections for foundation, framing, mechanical, plumbing, electrical, and final. Some projects require third-party special inspections.
8. Close out and receive CO. Upload final documents such as the improvement location certificate if needed, energy documentation, and the required Declaration of Covenants. After final signoffs and fee payment, the ADU is assigned as Unit B.

Who to call

• Arvada Building Inspections and Permit Counter: 720-898-7620
• Arvada Planning and Zoning: 720-898-7435

Fees you should plan for

• Building permit and plan review fees. Calculated on project value or square footage, plus trade permits as needed. Use the City’s fee estimator for a planning number. Run the fee estimator
• System Development Charges and meter fees. Arvada posts an annual schedule. The in-city residential SDC schedule lists a total of $46,640 per single-family unit for 2025, which includes the City’s water and sewer SDCs and a Metro Water Recovery SDC of $5,910. If your ADU adds plumbing fixtures, Metro Water Recovery SDCs apply before CO, and other tap or meter fees may also apply based on the City schedule. Arvada SDC and meter fees
• Design and engineering. Soils reports, stamped structural plans, and energy compliance documents are common for detached ADUs.
• Third-party inspections and recording. Some projects require special inspections and recording fees for deed restrictions.
• HOA approvals. If you are in an HOA, city permits do not replace HOA approvals and any related fees.

Note: Permit and plan fees vary with job value, while SDCs follow the posted schedule and can be one of the largest single costs if your ADU adds plumbing.

Timelines and what to expect

• City review targets: Type A about 3 weeks. Type B about 1 to 2 weeks for complete submittals. Actual timing varies with workload and revisions. Arvada review targets
• Typical project duration: Feasibility, design, and engineering often take 2 to 8 weeks. Plan review and issuance can take a few weeks to several months depending on complexity. Construction typically runs 3 to 8 months for detached units, and shorter for simple interior conversions. Local builders commonly cite roughly 4 to 8 months from design and permitting to completion, with permitting the most variable stage. Local builder timelines

Common pitfalls and practical tips

• HOA rules still apply. The City permit is separate. Confirm HOA approvals early. Arvada ADU overview
• Short-term rentals require licenses. If you plan to use the ADU for short-term rental, you need a short-term rental license and a business license and must follow city STR limits. Arvada STR requirements
• Expect an assessment change. New construction and permitted additions are typically assessable events. Contact the Jefferson County Assessor about valuation and appeals. Colorado assessment procedures
• Plan utility capacity early. If you add plumbing fixtures, Metro Water Recovery SDCs will be due before CO. Coordinate any meter upgrades with the City.
• Check parking and coverage by zone. Requirements vary by district, and state law limits excessive parking rules. Confirm the current code with a planner.
• Have complete documents at submittal. Missing stamps, energy documentation, or subcontractor listings can cause holds.
• Know the end result. Your ADU is a separate dwelling under building code and will be addressed as Unit B with a recorded declaration.

Quick document checklist

• Type A detached ADU:

  • Architectural plans with elevations and site plan
  • Stamped structural and foundation plans
  • Soils report and truss specifications
  • Mechanical load calculations (Manual J, D, S)
  • Utility and grading plans
  • Energy compliance (REScheck or HERS), gas-line calculations if applicable
  • Declaration of Covenants for the ADU

• Type B interior or attached ADU:

  • Floor plans showing separate unit layout
  • One-hour fire separation details
  • Energy and mechanical documentation if scope requires
  • Declaration of Covenants for the ADU

Ready to assess your property?

If you want a clear plan for an ADU that fits your lot, budget, and goals, let’s map it out together. From feasibility to resale strategy and rental positioning, you will get grounded advice and local execution. Start the conversation with Chad Goodale.

FAQs

In Arvada, do I use city or county ADU rules?

• If you are inside Arvada city limits, use the City of Arvada ADU rules and permits; if you are in unincorporated Jefferson County, use the County’s ADU process.

In Arvada, how big can a detached ADU be?

• Detached units are limited by two rules: no more than 40% of the main home’s living area and a lot-size cap of 600 to 1,200 sq ft depending on lot size.

What ADU fees should Arvada owners expect?

• Budget for building permit and plan review fees plus SDCs and meter fees; if you add plumbing, Metro Water Recovery sewer capacity fees apply before CO.

How long does Arvada ADU permitting take?

• The City targets about 3 weeks for detached and 1 to 2 weeks for interior ADUs for complete submittals, but total project timelines often span several months.

Can I rent my Arvada ADU as a short-term rental?

• Yes, but you must obtain a short-term rental license and a business license and comply with Arvada’s STR rules and limits.

Will an ADU change my property taxes in Jefferson County?

• New construction and permitted additions are assessable events, so adding an ADU can increase assessed value; contact the Assessor for specifics and appeal rights.

Do I need a separate water or sewer line for an ADU in Arvada?

• ADU plumbing ties into the principal dwelling’s services, and sewer capacity fees apply if you add fixtures; separate services are not typical for ADUs in the city.