Plant Prefab and Alchemy Architects Launch Net Zero–Ready Prefabs Starting at $170K

The new lightHouse LivingHomes are Plant Prefab’s smallest modular dwellings to date.
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Hot on the heels of a collaboration with Koto, California-based Plant Prefab is teaming up with St. Paul–based Alchemy Architects to launch a new line of modular accessory dwelling units (ADUs).

The lightHouse LivingHomes will be available in five categories—small, medium, large, extra-large, and 2X—that range from 310 square feet to 600 square feet. These flexible ADUs are available with a dozen floor plan variations—from a compact studio to a one-bedroom that can be built above a two-car garage.

Pictured is a rendering of a 570-square-foot 2X lightHouse with a one-bedroom unit stacked atop a two-car garage.

A rendered peek inside a 2X lightHouse model.

"Having worked together to build two prior homes in California, we’re confident that Plant Prefab is the right partner to bring our ADU designs to this market," says Geoffrey Warner, Principal Architect at Alchemy and weeHouse Founder. "The lightHouse is intended to be a beacon for sustainable living; Plant Prefab has built up its reputation around sustainable building practices."

Alchemy’s 15-plus years of experience with their prefab weeHouse line informed the design of the lightHouse, a flexible ADU that celebrates the motto "Luxury of Less."

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The first Plant Prefab–built modular lightHouse ADU was completed earlier this spring in Sebastopol, California. This 423-square-foot lightHouse was completed for around $285,000. That figure breaks down to approximate costs of $210,000 for design, engineering and production; $60,000 for infrastructure and site work; and $15,000 for shipping and installation.

Every lightHouse comes with a standardized high-performance envelope with thermally broken elements, a low-energy mechanical core with storage and laundry, energy-efficient windows, and a fir plywood interior. Custom built-in oak furnishings and signature elements (such as the unique steel awning, steps, doorplate, and exterior beacon) are also part of the design. The units will be customizable as well.

All lightHouses come with custom OxBox (oxidized steel) and Barn (wood) siding, as well as a collection of unique exterior steel features.

While Alchemy weeHouses may be site-built or panelized, Plant Prefab–manufactured lightHouse LivingHomes will all be modular prefabs. The partnership presently allows Plant Prefab to deliver lightHouses built via modular construction to California, Arizona, and Nevada.

The 480-square-foot large lightHouse starts at $199,999, and an entry-level version is available starting at $170,000.

Per Plant Prefab’s standards, the lightHouse LivingHomes will also meet net-zero standards and ship complete with smart home technology and energy monitoring. All LivingHomes are built with the Plant Building System, a patented hybrid system for building prefabricated homes that’s estimated to reduce build times by at least 50% compared to traditional construction.

More from Plant Prefab:

Plant Prefab and Koto Launch New Net-Zero Homes With Scandinavian Style

Plant Prefab Unveils Scalable Homes for California Wildfire Victims

Plant Prefab Just Unveiled its Most Advanced Homes to Date


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