Napa housing projects demonstrate benefits of modular construction

2022-06-16 20:09:46 By : Ms. Mandee Liu

In four hours Wednesday, a 1,300-square-foot house in Napa went from slab to completion.

No, it wasn't an all-hands-to-hammer benefit workbee that put up the three-bedroom, two-bathroom home on Dealy Lane in hours instead of months. Instead, it was done by a California startup that's part of a growing move into factory-built housing.

One of the firms building homes in a factory instead of onsite is Factory_OS which is ramping up this spring in a 275,000-square-foot factory on Vallejo's Mare Island. That company already has orders for thousands of factory-built dwellings for Google and municipal housing authorities.

Napa-based Healthy Buildings USA has its much smaller factory turning out panels for installation at a 48-unit development under construction in the city.

The Napa home on Dealy Lane is the first in the North Bay for nearly 2-year-old Plant Prefab, which also last week installed over two days a custom 16-unit dormitory in Berkeley for educational farm and community center Urban Adamah. It is said to be the first prefabricated multifamily project in the East Bay city.

In the past year, Plant Prefab opened its own factory, secured $3.4 million in series A funding led by Obvious Ventures and shipped six other housing units throughout California. The 62,000-square-foot facility is located in Rialto, located midway between Los Angeles and Palm Springs.

The single-story Napa home was built there in three dwelling modules plus a roof unit. The sections were then shipped to a staging area near the construction site, where crews were finishing preparation of the foundation. With construction in the factory occurring concurrently with build-site preparation, the total time to get the home from dirt to dining room can be reduced by as much as half, and neighborhood disruption can be lessened, not to mention potential for less waste in construction materials, according to founder and CEO Steve Glenn.

'In that area, it's important to consider prefab as a solution, because contractors so busy, and costs going up,' Glenn said.

The company has other North Bay projects in the pipeline, particularly for those who were among the thousands who lost homes in the North Bay's October wildfires, according to Glenn. The company is working with four such owners to install two homes in the coming months in Santa Rosa on burned sites and two outside the scorched areas — one in Sebastopol and the other in Half Moon Bay.

The Southern California company is offering special pricing for victims of the fire, including free initial site assessments, half-off of feasibility services, $5,000 in free upgrades and 5 percent off design and administrative fees.

Plant Prefab was spun off from LivingHomes, a designer of dwellings that conform to high levels of the LEED for Homes green-building standard. The Napa home is based on the LivingHomes C6P ranch-style home with a pitched roof and targets the highest level of LEED for Homes, which is Platinum.

While the owner of the Napa home may or may not pursue the arduous certification process for LEED for Homes Platinum, the modules were built to tick off items on that checklist, Glenn said. The modules are plumbed to connect to greywater recycling systems, have roof blocking and conduits for solar panels and are finished with low- or nonvolitile-organic-compound (VOC) paints.

LEED for Homes Platinum is hard to get because it involves water usage, flyash content of the concrete, indoor air quality, according to Bob Massaro, founder of Healthy Buildings USA in Napa and a longtime member of the local chapter of the U.S. Green Building Council, which created the LEED standard.

'I've not seen any factories be able to build to LEED (for Homes) Platinum,' Massaro said. 'Michelle Kaufmann and BluHomes tried to do it, but I have not seen it work long term. Plant Prefab would be the first.'

Kaufmann is considered a pioneer in high-end modular housing and operated a prefab company in the East Bay. BluHomes had been operating in the same building Factory_OS now has before exiting about a year ago and outsourcing manufacturing.

'One of my business principles is to keep overhead small,' Massaro said about his decision to keep his factory on a small scale. But California's approval of the accessory-dwelling-unit ordinance last year and the loss of so many homes in Sonoma, Napa and Mendocino counties from the wildfires has brought competition from a number of modular-home companies looking to market to fire victims, he said.

Massaro's factory is currently focused on building light-gauge steel panels for the company's Napa Creek Village project in Napa. Slowed by the heavy rains of last year, the project now has two of the eight residential buildings erected, and a foundation is being poured for a third.

To achieve its LEED for Homes Platinum target, Healthy Buildings USA designed Napa Creek Village with greywater recycling for the showers to go into irrigation and a wafflemat foundation system designed to reduce the amount of concrete.

The estimate for the LivingHomes C6P model that was installed in Napa in hard construction costs is about $275 a square foot, as figured for the Los Angeles area, plus at least 8 percent for soft costs such as design and engineering. The company works with local contractors for installation and also works with clients' design teams.

'We're set up to do rectolinear projects,' Glenn said. 'If you want undulating curves, we couldn't do that, but the vast majority of designs are rectolinear. We let clients know about changes they would need to make to build their home most efficiently in the factory. Some are willing to do the changes, and some won't. We don't make claims we can do everything.'

Many think of factories of turning out mass quantities of the same product, as in electronics or cars, but facilities for making big items such as homes, airplanes and ships often are configured to allow for customization from one unit to the next, Glenn said.

'For each boat or plane, they have each component for that model delivered to each station, so they can do custom work more efficiently,' he said.

The Napa and Berkeley projects are wood-framed, but an upcoming single-family home project on the San Francisco Peninsula is specified for light-gauge steel framing. The factory is also set up for working with heavy structural steel needed for larger projects.

Jeff Quackenbush (, 707-521-4256) covers the wine business and commercial construction and real estate.