Thinking about adding an accessory dwelling unit to your Arvada property? You’re not alone. Homeowners are turning to ADUs for flexible space, rental income, and multigenerational living. The key is understanding what Arvada will allow on your lot, how to permit it, and what it will cost. In this guide, you’ll learn the zoning must-checks, the approval path, typical budgets and timelines, and the practical choices that make an ADU work. Let’s dive in.

What is an ADU and why build one?

An accessory dwelling unit is a secondary home on the same lot as your primary residence. It can be a backyard cottage, a garage conversion, a basement apartment, an internal suite, or an addition attached to the main house.

Homeowners consider ADUs to create rental income, host family members, increase property value, and add privacy and flexibility. In Arvada, your path depends on zoning and building codes, so your first step is confirming what your lot allows.

First checks: zoning and eligibility

Before you sketch floor plans, confirm if an ADU is allowed on your property and what form it can take. These checks will save time and money.

Confirm your zoning district

Ask the City of Arvada Planning Division whether ADUs are permitted by right, require a special use or conditional use permit, or are not allowed in your zoning district. If a hearing is required, planning staff can explain the public notice steps and timeline.

• What to ask: Is an ADU allowed on my lot? If conditional, which board reviews it and what are the submittal requirements?

Unit types and size limits

Arvada may differentiate between attached ADUs, detached ADUs, internal conversions, and garage conversions. Detached units often have more site design rules.

• What to ask: What types of ADUs are allowed on my lot? What are the maximum square footage limits and bedroom caps for an ADU relative to my primary home or lot size?

Height, setbacks, and coverage

Detached ADUs are commonly subject to maximum height, side and rear setbacks, and lot coverage or impervious surface limits.

• What to ask: What are the height and setback standards for an ADU in my zone? Will my existing house, garage, and patios push me over lot coverage limits?

Lot size and overlays

Some cities require a minimum lot size for a detached ADU or treat flag and narrow lots differently. Overlay districts or conservation areas can add design rules.

• What to ask: Is there a minimum lot size, and does any overlay apply to my property that changes what I can build?

HOAs and private rules

Homeowners associations can be stricter than city code and sometimes prohibit secondary units.

• What to check: Your CC&Rs and HOA board guidance before you invest in plans. Even if the city allows ADUs, an HOA can limit or block them.

Parking, access, and utilities

These site logistics affect both feasibility and cost.

Parking requirements

Arvada may require one or more off-street parking spaces for an ADU. Some cities allow waivers or shared parking in certain cases.

• What to ask: How many off-street spaces are required for an ADU on my lot? Are there situations where parking can be reduced or waived?

Utility connections and addresses

Clarify how the ADU will connect to water, sewer, electricity, and gas. Separate meters or addresses can increase cost, and utility companies may have their own rules.

• What to ask: Can the ADU share existing utility services, or are separate meters or taps required? Are there tap or connection fees? Can the ADU receive a separate address for mail and emergency services?

Building, safety, and design basics

ADUs must meet the building, fire, and energy codes Arvada has adopted. These standards keep occupants safe and comfortable.

Code compliance for conversions

Basement and garage conversions often trigger upgrades that homeowners do not expect. Egress windows or doors, fire separation between units, insulation, ventilation, smoke and CO detectors, and safe electrical and plumbing systems are common requirements.

• Tip: Plan for egress and fire separation early. These items drive layout and budget.

ADU types and cost ranges

Costs vary by scope and site conditions. Broad industry ranges help you set expectations before you get bids.

• Conversions, like basement or garage: approximately low tens of thousands to about 60,000 to 120,000 dollars depending on upgrades and finishes.
• New detached ADU: often 100,000 to 300,000 dollars or more depending on size, design, finishes, utility runs, and site work.

Key drivers include foundation and framing for detached units, utility upgrades, grading or drainage, driveway or parking, professional design fees, contractor availability, and code-required improvements. Get multiple bids and include a 10 to 20 percent contingency.

Energy and green options

Your ADU must meet current energy code. That typically means insulation standards, efficient windows, and right-sized HVAC. Consider mini-split heat pumps, low-flow fixtures, and solar-readiness to lower operating costs and boost long-term value.

Permitting and timeline in Arvada

Every project moves at its own pace, but most follow a similar path from concept to keys.

The typical process

1. Pre-application: Talk with Arvada Planning staff to verify zoning, unit type options, and any special approvals.
2. Zoning review: If your ADU is permitted by right, you proceed to building. If conditional, apply for the required permit and any hearings.
3. Building permit application: Submit drawings showing code-compliant structure, egress, fire separation, mechanical, electrical, plumbing, and energy details.
4. Plan review: The Building Division reviews submittals. You may need stamped plans from an architect or engineer depending on scope.
5. Inspections: Expect inspections for foundation, framing, electrical, plumbing, mechanical, insulation, and final.
6. Final approval: Obtain the final approval or certificate of occupancy so the ADU can be legally occupied and rented.

Documentation checklist

• Site or plot plan with lot lines, setbacks, structures, parking, and utility routes
• Floor plans and elevations for the ADU
• Structural, mechanical, plumbing, and electrical plans
• Energy compliance documentation based on current code
• Applications for zoning verification, variances or special use permits if needed
• Demolition permit if you are removing an existing structure

Timelines and reviews

Plan for 1 to 4 weeks to schedule a pre-application meeting, 2 to 8 weeks for zoning or planning review, and 2 to 8 or more weeks for building plan review depending on workload and plan completeness. Construction can take several months to a year. For straightforward projects, budget at least 3 to 6 months for approvals. If you need a variance or public hearings, allow 6 to 12 months or more from concept to final approval.

Renting your ADU in Arvada

Rules for occupancy, lease length, and short-term rentals vary by city. Confirm Arvada’s current standards before you underwrite your project.

Owner-occupancy and lease length

Some cities require the owner to live on the property when an ADU is present. Others limit the number of unrelated occupants or set minimum lease terms.

• What to ask: Does Arvada require owner-occupancy for parcels with an ADU? Are there minimum lease lengths or occupancy limits for rental units?

Short-term rentals

Short-term rental rules change often and may require separate permits or may restrict ADUs from being used as short-term rentals. Verify the current ordinance and permitting process.

• What to ask: Can an ADU be rented as a short-term rental in Arvada, and if so, what permits and taxes are required?

Taxes and insurance

Adding an ADU generally increases assessed value and property taxes. The Jefferson County Assessor will evaluate improvements and adjust assessment. If you plan to rent, notify your insurance carrier. You may need a landlord endorsement or additional liability coverage.

Pro tips to avoid delays

• Start with zoning. Confirm allowed use, size, and setbacks before you design.
• Talk to utilities early. Connection requirements and fees can change feasibility.
• Design for code from day one. Account for egress, fire separation, and insulation in your layout and budget.
• Get multiple bids. Contractor capacity and scope assumptions vary widely.
• Communicate with neighbors. If hearings are needed, early outreach can reduce friction about privacy and parking.
• Keep records. Save emails, meeting notes, review comments, and permit numbers for future resale and insurance.

Where to verify and who to call

• City of Arvada Planning Division: Zoning, allowed uses, setbacks, parking, overlays, and pre-application guidance.
• City of Arvada Building Division: Building permits, plan review, inspections, and code requirements.
• Local utilities: Water and sewer capacity and tap fees; electric and gas metering and service upgrades.
• Jefferson County Assessor: Assessment changes and tax implications after adding an ADU.
• Colorado housing and energy resources: Possible financing or efficiency incentives that can apply to ADU construction.
• Your HOA: CC&Rs and architectural review requirements that may limit or prohibit ADUs.

Your next steps

1. Verify your zoning and ADU standards with Arvada Planning.
2. Review your CC&Rs and talk with your HOA if applicable.
3. Schedule a pre-application meeting with Arvada Planning and Building.
4. Get preliminary designs and two to three contractor or architect bids, including expected utility costs and tap fees.
5. Prepare your submittals and budget for review timelines and inspections.
6. Plan your rental strategy. Confirm lease rules and short-term rental policies before underwriting income.

Ready to evaluate your property, run rental numbers, and map the permit path? Connect with the investor-agents at Good Neighbor Realty for a free valuation and an ADU investment plan tailored to your lot and goals.

FAQs

Is my Arvada property zoned for an ADU?

• Contact Arvada Planning with your address to confirm your zoning district and whether an ADU is permitted by right or requires a special or conditional use permit.

How big can an ADU be on a typical Arvada lot?

• Size caps vary by zone and ADU type; ask Planning about maximum square footage, bedroom limits, and any percentage limits tied to your primary home or lot.

What are the parking rules for ADUs in Arvada?

• Many cities require at least one off-street space for an ADU, but standards and waivers differ; verify required spaces and any exceptions for your zoning district.

Can I convert my existing garage into an ADU in Arvada?

• Often yes, but you must meet building code for egress, fire separation, insulation, and mechanical systems, and you may need to address replacement parking.

How long does ADU permitting take in Arvada?

• Plan for 3 to 6 months for straightforward approvals and 6 to 12 months or more if variances or public hearings are required; construction adds additional time.

How much will an ADU cost to build in Arvada?

• Very rough ranges: 60,000 to 120,000 dollars for many conversions and 100,000 to 300,000 dollars or more for new detached units, depending on scope and site.

Do I need a separate utility meter for an ADU in Arvada?

• It depends on utility rules and city requirements; confirm whether shared services are allowed, whether tap fees apply, and if a separate address can be assigned.

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

• Short-term rental rules change and may require separate permits or restrict ADUs; verify the current ordinance and permitting steps with the city before you plan revenue.

Will an ADU increase my Jefferson County property taxes?

• Adding an ADU is an improvement that typically increases assessed value; confirm assessment impacts and timing with the Jefferson County Assessor.

What insurance changes are needed for an ADU in Arvada?

• Notify your insurer before construction; expect policy adjustments for the additional unit and consider landlord and liability coverage if you plan to rent.