How to Choose the Right Size ADU for Your Property in Colorado

Why Size Matters for Your ADU

Choosing the right size for your ADU isn’t just about square footage—it’s about balancing functionality, cost, and compliance. Here are the main factors to consider:

1. Functional Needs

The size of your ADU will largely depend on its intended purpose. Are you building for:

• Rental Income: A larger unit with multiple bedrooms may appeal to families, while a studio could suit single renters.
• Family Use: If it’s for aging parents or adult children, consider how much space they’ll need for comfortable living.
• Home Office or Guesthouse: A compact ADU might be perfect for occasional use or as a dedicated workspace.

2. Local Regulations

Colorado municipalities have specific rules governing the size of ADUs. These regulations typically define:

• Maximum Square Footage: Many cities cap ADU size at 1,200 square feet or a percentage of the primary residence.
• Height Restrictions: Detached ADUs often face height limits to maintain neighborhood aesthetics.
• Lot Coverage: Rules may dictate the total footprint of all structures on your property, including the ADU.

3. Budget Considerations

Larger ADUs naturally cost more to build. Materials and labor all scale with size but the cost per square foot does go down, so it’s important to balance your wishlist with your budget.

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4. Resale Value Impact

An appropriately sized ADU can significantly enhance your property’s resale value. Overbuilding may not yield proportional returns, while an ADU that’s too small might not attract future buyers or renters. Work with experts to assess the best size for long-term value.

Local ADU Size Regulations in Colorado

Understanding local zoning laws is critical when planning your ADU. Here’s an overview of common regulations in Colorado cities:

Denver

• Maximum Size: 1,000-1,200 square feet or 50% of the main home’s size.
• Height Limit: 24-30 feet for detached units.
• Lot Coverage: ADU must not exceed 40% of the property’s total area.

Boulder

• Maximum Size: 800 square feet or 10% of the lot size, whichever is smaller.
• Additional Rules: Must match the architectural style of the main home.

Fort Collins

• Maximum Size: 800-1,000 square feet.
• Lot Coverage: ADUs must adhere to a combined maximum footprint with the primary residence.

Westminster and Aurora

• Maximum Size: Up to 1,000 square feet.
• Lot Coverage: ADUs are limited to 30-40% of the lot, with strict rear and side setback requirements.

Golden

• Maximum Size: 800-1,000 square feet depending on lot size.
• Additional Rules: Designs must align with the city’s historic preservation guidelines in certain neighborhoods.

Arvada

• Maximum Size: 1,000 square feet or 40% of the main home’s size.
• Lot Coverage: Combined total of all structures must not exceed 50% of the lot.

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Lone Tree

• Maximum Size: 1,200 square feet.
• Additional Rules: Requires architectural review to maintain neighborhood aesthetics.

Highlands Ranch

• Maximum Size: 900 square feet.
• Additional Rules: HOA approval is required, and designs must comply with community guidelines.

Castle Rock

• Maximum Size: 1,000-1,200 square feet depending on zoning.
• Additional Rules: Detached units must meet strict setback requirements.

Lakewood

• Maximum Size: 1,000 square feet.
• Additional Rules: ADUs must adhere to lot coverage limits and blend with the architectural style of the primary residence.

Smaller Municipalities

Rules in smaller towns and unincorporated areas may vary significantly. Always check with local zoning offices to confirm requirements. Working with a design-build firm that knows the rules and regulations in detail from start to finish will ensure your project moves smoothly and you don’t encounter any costly delays.

How to Assess Your Property’s Potential

Not every lot is suitable for every size of ADU. Here are the key factors to evaluate:

1. Lot Size and Shape

• Larger lots can accommodate bigger ADUs, while smaller or irregularly shaped lots may require creative design solutions.
• Measure your available space to determine the ideal footprint.

2. Existing Structures

• The position of your primary residence, garage, or other structures will influence where your ADU can go.
• Detached ADUs often require more space and setbacks, while attached units can utilize existing walls or foundations to maximize efficiency and save on costs.

3. Utility Access

• Consider where water, sewer, gas, and electrical lines are located.
• Larger ADUs may require utility upgrades, increasing costs and complexity.

4. Accessibility

• Ensure there’s adequate access for construction equipment.
• Accessibility for construction also involves evaluating parking for workers and temporary storage for materials, which could impact project efficiency.
  
  • These challenges can be navigated by the right design-build firm but still important to be aware of factors such as these.

5. Environmental Considerations

• If your property includes slopes, trees, or drainage challenges, these may affect the size and placement of your ADU. Consulting with a design-build firm can help identify solutions.

Attached vs. Detached ADUs: A Key Decision

When determining the right size for your ADU, deciding between an attached or detached unit is crucial. Both options offer unique benefits and influence how square footage is utilized.

Advantages of Attached ADUs

• Cost Savings: Utilizing shared walls or existing structures can reduce construction costs.
• Space Efficiency: Ideal for properties with limited lot space or strict zoning rules.
• Utility Connection: Easier to connect to existing water, sewer, and electrical systems.

Advantages of Detached ADUs

• Privacy: A standalone structure offers more privacy for occupants.
• Design Flexibility: Detached units provide greater freedom to customize layout and aesthetics.
• Avoiding Complexities: Detached ADUs bypass some challenges associated with integrating new construction into an existing structure.

Combination Approaches

• Garage Conversions: Converting an existing garage into an attached ADU can save space and money while still offering functionality.
• Above-Garage ADUs: Building above a garage combines the benefits of detached units with space efficiency.

Tailoring the ADU to Your Needs

Once you understand your property’s constraints, focus on tailoring the ADU to your specific goals. Here’s how:

1. Matching Space to Purpose

• For Rental Income: Aim for 1-2 bedrooms and functional amenities like a full kitchen and bathroom.
• For Family: Prioritize comfort and privacy. Include features like open layouts, natural lighting, and accessibility options.
• For Flex Space: Keep it simple but versatile, ensuring it’s suitable for both work and leisure.

2. Maximizing Efficiency

• Use space-saving features like built-in storage and multifunctional furniture.
• Design open floor plans to make smaller spaces feel larger.

3. Customization Options

• Consider how much you want to customize the design. A design-build firm can help create a layout that meets your exact needs while staying compliant.

The Benefits of Working with a Design-Build Firm

Navigating the complexities of ADU size, design, and regulations is no small feat. Partnering with a reputable design-build firm offers several advantages:

1. Streamlined Process

• A design-build firm handles everything from site evaluation to construction, ensuring a seamless experience.

2. Expert Guidance

• Professionals can interpret local regulations and recommend the best size and design for your property.

3. Customization Made Easy

• Work with architects and designers who tailor your ADU to your specific goals and property, whether it’s a modern rental unit or a cozy family space.

4. Space Optimization

• Experienced design-build ADU firms know how to make the most of limited square footage, ensuring every inch serves a purpose. Whether you’re working with 240 square feet or 1,200, they can maximize functionality and aesthetics.

5. Cost and Time Savings

• Integrated teams reduce delays and unexpected costs, ensuring your project stays on budget and on schedule.

6. Long-Term Support

• Many design-build firms offer post-construction support, ensuring your ADU remains in excellent condition for years to come.

Common Mistakes to Avoid When Choosing ADU Size

1. Overlooking Local Regulations: Ignoring zoning rules can lead to costly redesigns or permit denials.
2. Underestimating Utility Needs: Larger units may require upgrades to water, sewer, or electrical systems.
3. Neglecting Future Needs: Consider how your ADU will be used in the long term. A slightly larger footprint now could save you from needing renovations later.
4. Sacrificing Quality for Size: Bigger isn’t always better. A well-designed smaller unit can be more functional and visually appealing than a larger, poorly planned space.

Case Studies: Finding the Right Size

1. A Compact Solution in Loveland

A homeowner in Loveland wanted a small rental unit. With a lot size of just 6,000 square feet, the team at Kindred Tiny Homes designed a cozy 700-square-foot ADU that met local requirements and included a functional layout with one bedroom and a full kitchen.

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2. Multi-Generational Living in Fort Collins

In Fort Collins, a family needed a two-bedroom ADU for aging parents. Kindred Tiny Homes created a 1,000-square-foot attached unit with an open layout, ensuring comfort and accessibility.

3. Versatile Detached Unit in Westminster

A Westminster homeowner wanted a detached ADU that could serve as both a rental and guesthouse. Kindred Tiny Homes delivered an 800-square-foot unit with a flexible floor plan and modern finishes, maximizing utility and aesthetic appeal.

4. Above-Garage Unit in Denver

A Denver homeowner opted for an above-garage ADU to maximize space on a smaller lot. The design-build team worked within height and setback restrictions to create a functional 600-square-foot unit with a full kitchen, bathroom, and private entry.

Making the Right Choice for Your Property

Choosing the right size for your ADU is a balance of purpose, property potential, and compliance with local regulations. By carefully evaluating your needs and working with experts, you can create an ADU that enhances your lifestyle and property value.

At Kindred Tiny Homes, we specialize in tailoring ADUs to fit your vision and your property’s unique characteristics. From compact studios to spacious multi-bedroom units, we’re here to guide you every step of the way.

Ready to start your ADU journey? Contact us today for a consultation!

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