Catalyst Project: 1864 Duplex New Build

ARCHITECTS & DESIGNER / Seth Donnell, NCARB, Anthony Gengaro

SCOPE / Custom Home Build - Duplex

LOCATION & DATE / Denver, Colorado | 2023

The 1864 Duplex | Custom Build of Duplex Units

PROJECT OVERVIEW

The 1864 Duplex new build is a speculative residential development located in the growing Sunnyside neighborhood of Denver, completed in collaboration with a local developer partner. Completed while working at Work Shop Colorado, this modern duplex maximizes the potential of an extra-long urban lot, delivering two spacious units designed for functional living and thoughtful outdoor connection.

Each residence spans three levels: a main floor with open-concept living and dining, a second level with three bedrooms, and a third-floor flex space that opens to a private rooftop deck. A standout feature is the full-height glass garage door in each unit’s living room, which opens directly to the rear patio, promoting natural light, air flow, and seamless indoor-outdoor living. The layout also supports privacy and comfort, with private green spaces situated just in front of detached garages at the back of the property.

Architecturally, the 1864 project embraces a restrained, modern material palette—wood, concrete, black steel, and clean-lined forms—resulting in a residence that feels warm, durable, and contemporary. This project exemplifies Catalyst’s ability to integrate custom design within developer-driven workflows while elevating the urban living experience.

ARCHITECTURAL FEATURES

This duplex residential development in Denver’s Sunnyside neighborhood was designed to maximize both livability and long-term value. Situated on an extra-deep lot, the homes feature extended private yard space alongside generous interior square footage.

The three-level layout includes a main floor for living, a second story with bedrooms, and a third-floor flex space with rooftop access. Glass garage doors in the living rooms open directly onto rear patios, blurring the line between indoor and outdoor living. Detached garages integrate with the rear yard space for added functionality.

Modern finishes—custom tile, warm wood tones, and minimalist lighting—create an inviting aesthetic, while strategic window placement ensures natural light and airflow throughout. Every detail was designed for durability, comfort, and long-term livability.

CUSTOM FEATURES

Exterior / Brick with three-coat stucco

Windows / Andersen 100

Doors / Overhead Door

STRUCTURAL ENGINEER / GEI Structural Engineer

BUILDER / Workshop Colorado

PROJECT GALLERY

A crisp concrete walkway leads to each residence, framed by native landscaping and modern form.

Private outdoor space with direct access from the living room creates effortless indoor-outdoor flow

Distinct entry porches provide identity and privacy for each residence.

A custom stair railing detail adds sculptural rhythm to the central circulation space.

Clean lines, refined tile, and warm lighting give this bathroom a serene atmosphere.

A floating staircase links all three levels and amplifies natural light throughout the core.

The living room’s minimalist fireplace is complemented by large openings to the rear patio.

An unconventional garage door in the bedroom brings abundant light and fresh air into the space.

A sleek, modern kitchen centers around the range and carefully coordinated cabinetry.

The open-concept plan integrates the kitchen and living spaces with light, movement, and ease.

A dedicated dining area is framed by natural materials and soft, directional lighting.

A secondary kitchen angle showcases custom millwork and connection to outdoor living.

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CLIENT REVIEW

★★★★★

"I am a home remodeler and house flipper and would use these guys for any project! They really listen to you and your needs and design what is best for your needs. They are well versed in city code and put together a complete set of plans within a couple weeks of signing the contract. Their plans were so complete the city only had a few minuscule comments and I have a permit in hand just over 2 months of getting catalyst started which is pretty unbeatable! Highly recommend!" - Paige Schmitz