New England isn’t the first place that comes to mind when we think of tornado country, but in one day in August, five touched down in Massachusetts, Connecticut, and Rhode Island. Alongside a housing shortage, some of the oldest housing stock in the nation, and the creep of climate change, resilience is moving to the top of the list of priorities when it comes to home building here.
Proponents of a modular form of concrete building say their storm-proof and fireproof method could help on all fronts, and they’ve partnered with a national nonprofit to help prove their case. In the Pioneer Valley, two of those projects are underway.
The insulated concrete form, or ICF, first emerged about 40 years ago, and was mostly used in Europe and Canada. But over the past decade, manufacturing improvements — paired with ICF’s ability to stand up to severe weather — have increased its appeal. The format uses recycled foam templates that are reinforced with steel and then pumped with concrete. The panels are used to construct a self-insulating home that should last hundreds of years. The National Ready Mixed Concrete Association pitched its Build with Strength Program to Habitat for Humanity in 2020 with an aim to build one ICF home in every state.
“I describe them as Lego blocks,” said Aimee Giroux, executive director of Habitat for Humanity of Greater Springfield. In August, Habitat Springfield used ICF to build the foundation of an addition, which will create an adaptive expansion for a veteran with mobility needs. A Holyoke project is using ICF from the basement to the upper floors, and at press time was approaching the drywall phase.
“It creates a very strong structure and a very well-insulated structure,” Giroux said.
Gregg Lewis, an architect and spokesman for the concrete association, said an ICF home, if constructed properly, should stand up to almost any hurricane or tornado. “An ICF and concrete wall can withstand a 250-mile-an-hour wind load,” he said.
The International Building Code rates 6-inch ICF blocks, which Habitat for Humanity uses, at four hours to resist fire, compared with 20 minutes for wood.
Lewis described himself as a longtime fan of Habitat for Humanity’s work, which he first observed while studying at Yale, where students partnered with the organization. Build with Strength now counts about 70 home projects underway in 33 states, he said.
Unlike a “cavity wall,” or what most would consider a traditional build, the “mass wall” of a concrete build provides increased insulation because it does not need to be padded with fiberglass. Proponents say that results in utility savings because the home maintains a more constant temperature throughout the day, as well as soundproofing benefits.
Giroux said Habitat for Humanity appreciates the approach’s sustainability features: ICFs emit fewer volatile organic compounds than traditional materials, which means less exposure for inhabitants, and the foam board is made from recycled products.
Lewis said: “One of the reasons I wanted to work with Habitat is it gave us an opportunity to ... showcase some of these new carbon-reducing-mix designs and show that they are no different, really, in terms of their performance to a more traditional concrete.”
But how does the ICF look?
“We were calling it the big, white whale,” Giroux said of the blazingly white exterior, which she said attracted many questions from onlookers. But once the drywall and vinyl siding are added, the home blends in, she said. “It’s been a great way to draw attention to our project.”
Concrete can call to mind the Brutalist look of some well-known municipal buildings, but that’s not the case for finished ICF projects, Lewis said.
“Heaven forbid you tell anybody that you’re building a concrete house, because that conjures up images of Boston City Hall or some [other] kind of Brutalist concrete, gray building,” he said. “The reality is that when an ICF house is actually finished, it can look like virtually any other house.”
Lewis said that across the country, Habitat for Humanity homes using ICF were customized to fit the local character: An Adobe look passed architectural muster in Santa Fe and Denver, for example.
Habitat for Humanity builds homes for income-limited applicants who qualify to partner with the organization, assisting with the build itself alongside a team of volunteers. Giroux said her group takes about 15 months to finish a project from application to closing.
For Habitat for Humanity, ICF presents a unique benefit: It’s more accessible for novices. “You can pick up a 4-foot wall of this and move it really easily. [It’s] not like having to deal with all of the plywood and everything else that’s a lot heavier,” Giroux said.
Giroux added that the partnership included on-site technical guidance from the group: “It was a very new way to build for us. It was a little bit of a learning curve. But it’s been really interesting and I’m glad we did it.”
Last year, Habitat’s Greater Springfield affiliate received 120 applications for housing assistance. The organization had funds to take on one project. In a given year, it takes on two to three projects in Greater Springfield and 25 to 30 statewide. Cost is the primary limiting factor, but Giroux said it is too soon to tell how much money, if any, will be saved using ICF.
Building with ICF isn’t without its challenges.
Giroux noted that the seamless nature of ICF construction means ventilation is important to support adequate airflow and air turnover. Lewis added that solid planning is vital; ICF is permanent construction and isn’t easy to modify once the project is completed.
But advocates say ICF’s ease of use and qualities make it one tool in the push to provide more housing.
“Our mission is to build affordable housing that’s sustainable and helps the families to become a little bit more self-reliant,” Giroux said, so helping with home efficiencies and lowering utility bills is important.
Lewis said ICF represents one piece in a bigger puzzle.
“If you say, we’re going to solve this with one building system versus another, I just don’t think that that’s true,” he said, but integrating as many systems as possible customized by local needs is a step in the right direction.
“The speed of construction of ICF makes it a lot easier to build more of them more quickly,” he said. “There’s also an obvious benefit to not having to build a house more than once, because you’ve built in a place where hurricanes or tornadoes or wildfires are burning down houses faster than we can build them.”