Energy-Efficient Prefab Homes

The couple behind Mandala Custom Homes has fine-tuned the ultimate prefab package. When I first reached out to Lars Chose and Rachel Ross, owners of Mandala Custom Homes, they were in Hawaii conducting a site visit for a new project on Kauai. They had a full itinerary with plans to attend a trade show in Kona and to host an open house at an...

The couple behind Mandala Custom Homes has fine-tuned the ultimate prefab package.

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“We shape our buildings and thereafter our buildings shape us.”—Winston Churchill

When I first reached out to Lars Chose and Rachel Ross, owners of Mandala Custom Homes, they were in Hawaii conducting a site visit for a new project on Kauai. They had a full itinerary with plans to attend a trade show in Kona and to host an open house at an oceanfront Mandala Home before heading to B.C., Canada, their home and headquarters. Business is booming.

Since 2000, the two have been designing, prefabricating, and shipping building packages all over the U.S. and Canada—90% are single-family homes, the rest are public and commercial spaces, such as retreat centers, yoga studios, and interpretive centers.

Their offerings are unique.

Having built Minnesota’s first ENERGY STAR-certified home in 2003 and B.C.’s first in 2011, the pair are well-versed in energy efficiency and building science. “Because we ship homes all over North America, we really had to understand climatic zones and their effects on building envelopes,” says Lars, who has become an expert in climate-specific wall and roof assemblies. He recalls working with the engineer in charge of developing B.C.’s energy code; they were tasked with designing the most energy-efficient building envelope possible—that meant moving the air and vapor barriers to the outside of the wall, which was a unique approach back in the early 2000s.

Fast forward nearly 20 years, and Lars and Rachel have perfected their Mandala Custom Homes package, which includes: a customized design, an ENERGY STAR consultation and audit, permit sets, construction drawings, engineering documents, a climate-specific building envelope, and print as well as digital assembly instructions. They even offer construction loan and mortgage services in the U.S.

Mandala homes are freestanding faceted structures without internal load-bearing support that are engineered for seismic activity, wind, and snow load. The pre-built components—assembled and finished by local contractors—include the floor system, the roof system (engineered scissor trusses and pre-cut sheathing), and pre-sided wall panels with the windows installed. The wall assembly includes rain screening, exterior rigid-foam insulation, and siding. Foundations are designed by an in-house engineer and are based on a geo-tech’s soil report; typically they are full basements or ICFs.

Most homes are built with kiln-dried FCS Douglas fir; and the ceiling, trim, and siding are western red cedar, though climate and customization may influence material choices. If shipping to hot, arid climates, for example, they will build wall panels ready to receive stucco or Hardie cement fiber board.

According to Rachel, the building package comprises an average of 50% of the total building, depending on customization factors. And the price per sq. ft. is roughly $120. The prefabrication process is based on the Lean Manufacturing model; their design studio focuses on making houses that are easy to transport and build.

Why round? Lars notes the inherent strength of the shape. It is also easily engineered because of the connectivity of all components. Additionally, it supports green building principles: A round structure uses 20% less materials for a building envelope of the same square footage as a conventional home; and it loses less heat because there are fewer transitions, connections, and seams. As a musician, Lars also appreciates the exceptional acoustics a round form provides.

Rachel stresses the customization aspect of their offerings as paramount, noting that it is “a dance between the clients’ preferences, the needs of the site, and the budget.” Of the different models they offer, she says the Magnolia and Elmwood are most popular, though in Hawaii, clients gravitate toward the Juniper, which is two connected mandalas—the larger models are ideal for multigenerational family compounds.

As an endnote, Lars muses: “My building career started and was inspired by Fine Homebuilding magazine. Talking to you now, I realize it has come full circle—so to speak.”

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Source: www.finehomebuilding.com