An Age-Ready Garage ADU Conversion
Project Overview
The homeowner needed an age-in-place–ready ADU with flexibility for future use. Prenvalley Builders completed a full garage-to-ADU conversion, navigating tight site conditions and existing structure constraints. The result is a durable, thoughtfully built space with long-term adaptability, including future second-story potential.
Project Details
Size: 650 sq ft
Location: Denver, Colorado
Architectural Design: Prenvalley Builders
Interior Design: NAGY Design Co.
Our Approach
Prenvalley Builders approached this ADU with a construction-first mindset, focusing on durability, efficiency, and long-term performance. Working from an existing design, the team carefully coordinated structural upgrades, systems integration, and exterior envelope improvements to ensure the space would age well over time. Clear communication and disciplined execution allowed the project to move smoothly despite tight site constraints.
Project Highlights
Full garage-to-ADU conversion and addition
Age-in-place–ready construction and layout
Structural upgrades to support future second-story expansion
High-performance exterior envelope and durable materials
Efficient one-bedroom ADU with full kitchen and bath
New windows, doors, and concrete flatwork
Improved site access and privacy through exterior upgrades
Results
The completed ADU provides a comfortable, accessible living space that meets the homeowner’s current needs while allowing for future expansion. Thoughtful construction detailing and durable materials ensure long-term performance and low maintenance. The result is a flexible, well-built addition that adds lasting value to the property.
Project Goals
Create an age-in-place–ready accessory dwelling unit
Maximize usable living space within an existing garage footprint
Ensure long-term durability and low-maintenance performance
Allow for future second-story expansion
Improve overall property functionality and value
Common Questions about Accessory Dwelling Units
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This varies quite a bit throughout Colorado based on your city’s specific zoning guidelines. Our team are experts with zoning rules throughout the state and can provide you with a detailed breakdown of what’s possible.
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We usually get asked how much an ADU costs per square foot but this is the hardest metric for an ADU since the cost per square foot parameter can vary drastically based on the size. This is due to the fact that ADUs are small compared to normal homes and the cost per sq. ft. can vary dramatically due to the economy of scale factor. Also, most of the ADUs we build have unfinished garages which complicates that metric even further. We’ve found that ADUs in Denver can vary on average from $250k to $450k based on size, finish level, and site constraints.
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As of right now the average ROI ranges from 4 to 7 years until you begin seeing a net positive on your ADU investment which is based short term renting the space over that time. The problem with ADUs in Colorado is that there aren’t many comparables when appraisers are valuing these spaces so they are typically appraised at a lower value than they were built for. As more ADUs are built and sold with their primary homes, these numbers will improve so this ROI is very much temporary. As of now, ADUs are considered a long term investment and are definitely worth the consideration if you’re looking to hold onto your home for the long run.
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In our experience thus far, the scale of an ADU hasn’t been proven to be built better or more cost effective in a modular format. The modular ADU on paper seems like a great idea but all of the companies we’ve seen provide them are at a comparable price point if not higher and quality issues can occur due to manufacturing, delivery, and assembly issues. We view ADUs as custom small homes that need to be built with care and craftsmanship which can easily be lost in a mass manufacturing process.
