3D printed house shows potential affordable housing solution

The three-bedroom, two-bath home at 217 Carnation St., just off Midlothian Turnpike, will be the first house in Virginia partially constructed using a 3D printer rather than lumber. Work began this week and is slated to be completed in the fall.

Building exterior walls of the home using a giant printer is different than traditional construction, but it is easier to understand than you might think, said Andrew McCoy, director of the Virginia Center of Housing Research at Virginia Tech, one of the partners in the project to build the home.

“It’s really like we’re building a layer cake,” McCoy said of the process to construct the walls using a 3D printing system that places concrete atop of one another.

“It’s layer upon layer and, just like a layer cake, you have to worry about the consistency of each level,” he said. “You have to worry about how you are going to finish it. You have to worry about making sure that there’s all the ingredients, but baking is the critical part.”

Using 3D printing technology in home construction is faster, cheaper and more sustainable than traditional construction, and it is more energy-efficient after the house is built, experts say.

And because of those factors, using the technology could provide a potential solution to the affordable housing issues plaguing the state, said Susan Dewey, CEO of Virginia Housing, the not-for-profit housing finance agency that provided grant money for the 3D printing project.

“One of the things that we are finding is a big barrier right now is inventory,” said Dewey, noting a growing need for more affordable housing in the state. “It’s homeownership, it’s rental, and we’ve got to be thinking differently about housing.”

The 3D construction should be able to provide a more affordable way to build homes while lowering costs at least $10 per square foot compared to a traditionally built home using lumber, according to Virginia Housing.

“The hope is that we can produce the home between $180,000 and $190,000, and we can sell them for $210,000 to $220,000,” McCoy said.

Having a sale price in that range “is very affordable for this area, especially since you have seen an escalation in prices around the Richmond market,” said Chris Thompson, director of strategic housing for Virginia Housing.

The median sales price — with half the houses selling for more and half for less — in the Richmond area during the first three months of 2021 was $310,000, up 16% from a year ago, according to the Richmond Association of Realtors.

Selling more homes at a more affordable price is important in the Richmond region, where 66% of residents earn less than 30% of the area’s median income, which was $86,400 for a family of four in 2019; yet, those residents paid more than 50% of their income on housing in 2019, according to the Partnership for Housing Affordability.

Greta Harris, president and CEO of the Better Housing Coalition, a Richmond-based nonprofit affordable housing developer, said the Carnation Street house probably will be sold to someone who makes between 75% and 80% of the region’s median household income.

The Better Housing Coalition, which is part of the partnership for the 3D home project, is raising money to help the buyer with down payment assistance, she said.

The organization along with project:HOMES, a housing nonprofit based in Richmond, will work together to identify a homeowner to buy the 3D house as well as to help coordinate local permitting, zoning and insurance for the project.

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To help reduce the housing gap, Dewey hopes more 3D houses will be printed in the Richmond area in the future, but no plans have been made yet.

However, several homes elsewhere in Virginia are planned to be constructed using the technology.

This fall, a home is slated to be built in James City County, and five homes are planned for a compact neighborhood on the Eastern Shore. Those homes on the Eastern Shore will range in size from 500 square feet to 1,300 square feet.

The interior and exterior walls of the Williamsburg and Eastern Shore homes will be made with the 3D printer, while only the exterior walls of the house on Carnation Street in Richmond are being made with the 3D printer.

“For this home we are working on in Richmond, the goal is something that’s very approachable, that looks like any other home,” said Zachary Mannheimer, founder and CEO of Alquist 3D, a 3D printing construction company that bought the printer for the project.

Using 3D technology for the homes in Richmond and the others across the state came about from a partnership that Virginia Housing created with other entities to make this project possible.

Virginia Housing, the quasi-government agency formerly called the Virginia Housing Development Authority, provided a $500,000 grant to the Virginia Center of Housing Research at Virginia Tech to pursue the project.

The housing research center gave most of the grant money to Alquist 3D in order to buy the printer from Denmark manufacturer COBOD.

The 3D printer cost $370,000, but additional items such as a mixing bowl brought the total price tag to $430,000, said Virginia Housing’s Thompson.

RMT Construction and Development Group, which will do the more basic and traditional construction for the homes, is also in the partnership, in addition to project:HOMES and the Better Housing Coalition.

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A prototype wall was made on site last Thursday to make sure the ingredient ratio of water and cement was just right. That wall was taken down with sledgehammers after it cured.

The base of the house was made last Friday, Thompson said.

Starting early Monday, the printer began making the real exterior walls of the home.

Concrete comes out through a nozzle attached to the printer.

The printer then slowly follows a specific pattern that was made from a 3D model on a computer. The wall is then smoothed out with a different nozzle that has a scraper attached.

Printing a home is more cost-effective in the actual building process as well as in the long run, said McCoy from the Virginia Center of Housing Research.

This is because the concrete used is much more accessible than lumber, which has been in short supply over recent months.

Lumber costs also have soared this year.

The printer built the walls over the next several days, Thompson said.

The process typically would take 12 to 15 hours if done all at once, but the process has to be done early in the morning or late at night to make sure that the temperature does not affect the mixture, he said.

Once the process is perfected, only two or three contractors will be needed on site to monitor the printing process, he said.

“It is much different than when you have to have a crew of contractors here that are doing framing all at the same time,” Thompson said. “We will see a significant decrease in the (amount) of labor.”

The concrete used for the walls also will be better suited to inclement weather like tornadoes and hurricanes.

The material retains temperature so it will be less expensive to heat and cool the home.

When the home is finished, the savings do not stop there.

Virginia Tech has an indoor environmental sensor system that will monitor the home to make sure everything is working as efficiently as possible.