What is an ADU in Denver?

An ADU (Accessory Dwelling Unit) is a secondary living space on a residential property—often above a garage or as a detached structure—designed to add flexible housing without changing the character of the neighborhood.

Do I need a permit to build an ADU in Denver?

Yes—Denver requires permits, plan review, and zoning compliance for ADUs, and the process often includes site constraints, access requirements, and utility coordination.

How long does it take to build a two-story ADU above a garage in Denver?

Timelines vary by site conditions and permitting, but two-story garage ADUs typically require careful structural planning, approvals, and a coordinated construction schedule from foundation through final inspections.

What makes a high-performance ADU different from a standard build?

High-performance ADUs prioritize a tight building envelope, insulation, air-sealing, and durable materials to improve energy efficiency, comfort, and long-term maintenance.

Can an ADU be designed for privacy on an urban lot?

Yes—strategic window placement, exterior stair access, and thoughtful layout planning can improve privacy while maximizing space, especially on tighter Denver infill sites.

West Denver Renaissance ADU

ADUNew Construction

Feb 4

Written By Phillip Daughton

Project Overview

The client needed a durable, well-designed ADU that could support Denver’s growing housing needs while fitting seamlessly into an urban neighborhood. Prenvalley Builders designed and built a two-story ADU above a garage with exterior stair access, navigating tight site conditions and zoning requirements along the way. What makes this project special is its partnership with the Denver Housing Authority and its role in advancing thoughtful, community-focused housing solutions.

Project Details

Size: 650 sq ft

Location: Denver, Colorado

Architectural Design: Prenvalley Builders

West Denver Renaissance Collaborative

Finished two-story accessory dwelling unit in Denver with integrated garage and exterior stair access, built by Prenvalley Builders.

Our Approach

Prenvalley Builders approached this ADU with a clear, process-driven strategy—balancing efficient design, durable construction, and long-term performance. Working within a tight urban site and public-private partnership requirements, the team coordinated closely across design, permitting, and construction to deliver a high-quality housing solution. The result is a well-executed ADU that reflects Prenvalley’s experience with complex urban projects and high-performance residential building.

Project Highlights

Two-story ADU built above an integrated garage
Exterior stair access to maximize privacy and site use
High-performance building for durability and energy efficiency
Designed to meet Denver zoning and urban infill requirements
Constructed in partnership with the Denver Housing Authority
Part of the West Denver Renaissance Collaborative initiative

Early site preparation and foundation layout for a detached accessory dwelling unit by Prenvalley Builders in Denver, Colorado.

Framing in progress on a detached accessory dwelling unit built by Prenvalley Builders in Denver, Colorado.

Completed accessory dwelling unit with integrated garage and alley access, built by Prenvalley Builders in Denver, Colorado.

Results

The completed ADU delivers a durable, efficient living space that supports Denver’s evolving housing needs while fitting seamlessly into its urban context. Through careful planning and execution, Prenvalley Builders transformed a constrained site into a high-quality, long-term housing solution. The result is a project that balances performance, functionality, and community impact.

Project Goals

Create durable, long-term housing in an urban Denver neighborhood
Maximize usable space on a constrained infill site
Deliver a high-performance, energy-efficient ADU
Navigate zoning and partnership requirements efficiently
Support community-focused housing initiatives

Exterior insulation and air-sealing installation on a detached accessory dwelling unit built by Prenvalley Builders in Denver, Colorado.

Finished accessory dwelling unit in Denver with exterior staircase and upper-level entry, built by Prenvalley Builders.

Phillip Daughton