'I wanted to cry': Devastating risks of spray foam insulation hidden from Vermont homeowners

Londonderry contractor Abe Crossman was keeping busy with small projects at his family’s home in June 2020 during the newly arrived coronavirus pandemic. He was working outside when he noticed that the paint was peeling off the trim at the peak of the gable end of his roof.

With 25 years of building experience, he knew that peeling paint indicated the presence of moisture. But the location was odd — that trim underneath the overhang should stay dry. So he grabbed a ladder and a pry bar to take a closer look.

His stomach dropped as he sank the pry bar into the soft wood sheathing underneath the trim and peeled away the vinyl siding down to four feet below the roof line. What had been wood disintegrated into dust in front of his eyes, he later recalled, leaving behind nothing but spray polyurethane foam insulation.

At first, Crossman thought he might have a roof leak. But he found no issues with the standing seam roof. In any case, he said, when a contractor had installed spray foam insulation in his roof and second-floor walls a decade earlier, he had been promised that the type of foam used, open cell, would let water come through in case of a leak, so he should have noticed it immediately.

He headed inside to his daughter’s bedroom, cut a square out of the ceiling’s sheetrock and hacked at the spray foam so he could see the structure underneath it. He grasped a rafter, and it crumbled in his hand. The roof had dry-rotted.

“I was in shock and disbelief,” he told me this past winter. “I wanted to cry, honestly.”

He was starting to wonder if the spray foam itself might be the problem.

Vermont’s old homes desperately need to be insulated and upgraded. According to the U.S. Energy Information Administration, residential homes consume the largest share of energy in Vermont, representing 35% of its energy consumption, and account for one-fourth of Vermont’s petroleum consumption. About three out of four Vermont households use some sort of fossil fuel to heat their home. Only Maine and New Hampshire have a larger share of such homes.

The federal government and Efficiency Vermont both hand out rebates to encourage homeowners to weatherize their homes and reduce their oil consumption. The Inflation Reduction Act signed into law last summer provides new federal income tax credits of up to $3,200 annually to homeowners to help cover heat pumps, heat pump water heaters, new doors and windows, home energy audits and, of course, insulation.

While there are many types of insulation — cellulose, mineral wool, foam board and batting — the spray foam industry has benefitted mightily from this green weatherization push, since spray foam is such a terrific insulator and can be easily installed in one day without tearing out walls.

I experienced this push toward spray foam myself. In early 2022, my husband and I purchased a 180-year-old farmhouse in southern Vermont, near Londonderry. After my first $600 oil bill, I visited Efficiency Vermont’s website and found two certified energy auditors. One was booked for months, but the other showed up the next week.

After touring the house and doing a blower door test, he recommended we spray foam the cathedral ceilings, inside the knee-wall attic and in the basement.

I questioned how green it was to fill my walls with a fossil-fuel-based plastic product, but the energy auditor assured me that there wouldn’t be any problems; we would have heard about them if there were. And he knew a local spray foam installer. (I recently called him back, but he wouldn’t comment on the record for this story.)

Two days later, we had our first walk-through of the house with Crossman, whom we had hired as our contractor for renovations. When I shared the energy auditor’s recommendations and said that I had asked Chester-based Vermont Foam Insulation to give me an estimate, he gently cut me off.

“You know I’m suing Vermont Foam, right?” he said.

After Crossman left, I canceled my appointment and began investigating best practices for weatherizing my home. I figured, as a journalist with years of experience researching green materials, I would make quick work of it.

Instead, during what would become a year-long journey, I found myself in a thicket of contradictory, outdated or biased information. Plenty of horror stories lurked in forums and blogs: historical homes ruined, fishy smells, moisture problems and people falling ill.

Every terrible tale, however, was followed by an explanation excusing the foam. The homeowners didn’t run a proper ventilation system. They should have installed a vapor barrier. The contractor built the house wrong. That particular spray foam installer did a bad job. Anything and everything but the spray foam itself seemed to be the culprit.

I was left with more questions than answers. Are Vermonters unwittingly destroying their homes in their quest to be green? And how many people are about to peel back their own siding and find a nasty surprise?

For this story, I spoke with four Vermont building science experts, plus a building materials specialist, residential architects, contractors, homeowners, spray foam representatives, and a mold remediation expert. I dug through forums, building trade journals, news reports, and court cases looking for clues.

As I tried to cut through the noise of online comment sections, a clearer picture started to emerge.

Among the experts I talked to was Jacob Deva Racusin, the director of building science at the worker-owned cooperative New Frameworks in Burlington, which specializes in sustainable retrofits of older homes. He doesn’t want to demonize spray foam as a product, he said, but he’s seen the installation process go off the rails.

“I just see spray foam being used inappropriately very frequently without consideration around its moisture management applications,” he said. “It can be a real liability in (above ground) scenarios.”

Americans — and Vermonters in particular — are especially vulnerable to the risks of poor spray foam installation. In Canada, spray foam installers must be third-party certified. In the U.S., there are no legally-required training, educational or certification requirements for spray foam installers at the federal or state level.

Until last year, when the state passed legislation aimed at making housing more affordable, Vermont was one of the few states that didn’t require contractors to register with the state. And there was no way for homeowners to lodge an official complaint against any residential contractor, including weatherization contractors. Even now, most spray foam jobs cost less than $4,000, and the new law exempts jobs under $10,000. (State officials unveiled the registry earlier this month.)

Efficiency Vermont was partnered with Vermont Technical College to offer a free, voluntary educational program, the Building Performance Institute, for builders and weatherization contractors, but that partnership ended during the pandemic. It now provides online training with Green Training USA, and is requesting proposals for contractor training and testing.

And two trade organizations, the Spray Polyurethane Foam Alliance in Virginia and the Air Barrier Association of America in Massachusetts, offer voluntary professional certifications. The only Vermont spray foam contractor listed by either trade organization is an Overhead Door Company location in Williston.

When asked how a homeowner could assess whether they’re hiring a high-quality insulation installer, Brent Ehrlich, a products and materials specialist at BuildingGreen, an information platform based in Brattleboro, said, “I don’t really have a good answer to that.”

I asked Matt Sharpe, a senior building consultant for Efficiency Vermont, about the issue.

“We want to make sure whatever you’re doing to the house is not going to do more harm than good,” he said.

But he remained agnostic throughout our conversation as I delineated the potential risks from spray foam.

“Those are all legitimate concerns. And I think those concerns would all be legitimate to other products as well,” he said. “The performance of the work in general, no matter what material you’re using, is very important.”

Unfortunately, there’s currently a shortage of qualified weatherization experts and contractors in Vermont. Efficiency Vermont estimates that only 2,000 homes in Vermont are weatherized a year, when 13,400 homes need it to meet the state’s climate goals. Many other states report similar labor shortages in weatherization and residential construction.

“Weatherization is a higher-skill job than I think most people realize,” Sharpe said. “And it’s in horrible conditions. Not many people want to do it.”

The result is a Wild West of spray foam installation, raising questions about the long-term damage to homes and ruinous costs to homeowners who are just trying to do the right thing.

Polyurethane, also known as PU, was invented in Nazi Germany in 1937 by Dr. Otto Bayer, who discovered mixing isocyanates and polyol would create a special type of plastic. One of its first uses was for mustard-gas-resistant garments. After the war, manufacturers found other uses for it in an expanding range of consumer products, including fake leather, mattresses and foam insulation panels.

In the 1960s, the spray foam gun was invented, which allowed polyurethane foam to be sprayed to fit perfectly into any wall or ceiling cavity that needed an airtight seal — at the time, mainly industrial sites. The 1970s energy crisis, which drove the price of heating oil sky-high, made homeowners receptive to this new, super-insulating product.

But it was the Canadian spray foam manufacturer Icynene, founded in 1986, which pushed spray foam deep into the consumer market. The company sold its product to a network of independent contractors across North America, who in turn pitched it to homeowners as an easy and effective way to save on energy costs.

Here’s how it works. The spray foam contractor brings the chemical ingredients to your home in separate canisters. One contains the main ingredient for foam: highly reactive chemicals called isocyanates. The other contains a trade-secret mix that varies from manufacturer to manufacturer of polyol, fire retardants, catalyzing amines, blowing agents and other chemicals. These are mixed together through a tube and sprayed onto the unfinished wall, roof decking or into tight spaces, where the combined chemicals immediately expand into a foam.

There are two different types of spray foam. In open cell foam, the little air bubbles in the foam are broken open, leading to a spongy and soft foam. In closed cell foam, the air bubbles are completely encapsulated, for a harder and denser foam with higher insulation value. The latter is also more expensive to install but today is recommended over open cell foam for cold climates such as Vermont’s.

The most common spaces where spray foam is applied are inside walls, under the roof, inside attics, and on the walls of basements and cellars. Contractors often use it for tight spaces instead of using thicker types of insulation, in order to more easily fulfill building code requirements.

The application process makes spray foam unique among plastic consumer products. “Unlike a foam board product, which is manufactured in climate-controlled factory conditions where they can really manage quality control, you’re doing onsite chemistry,” said Racusin, the Burlington-based building science director.

The installation process releases toxic fumes, which is why spray foam technicians must wear a full protective suit and respirator. The foam spends the next day “curing,” or drying and hardening, during which time homeowners must vacate the property.

If all goes well, the spray foam is inert and done off-gassing by the time the homeowners are back inside. And it has fitted neatly into every space in which it was applied, with no holes or cracks, creating an airtight seal and a deliciously warm home — if everything goes right.

Several building science and material experts, however, say there are many ways spray foam application can go wrong.

Rick Duncan, the Maryland-based executive director of the trade group Spray Polyurethane Foam Alliance, said spray foam can be applied in every season because contractors can heat the home, heat up the material where it is being applied or use cold-weather foam. Below 40 degrees Fahrenheit is the absolute cutoff for proper application, but “the warmer the better in terms of getting the most out of your chemicals,” he said.

This may represent an optimistic view.

“The conditions where the manufacturers say that you should be mixing and installing this site-created insulation are very strict and almost never met in the field,” said Chris West, a Jericho-based certified consultant and trainer for Passive House, a design standard for ultra-low-energy-consumption homes. “It’s like, 80 degrees, and no dust and the perfect humidity of the material you’re spraying against.”

Although the U.S. Environmental Protection Agency says that more research is needed, it found that if the chemical mixture or temperature is wrong, it can fail to cure and may continue off-gassing amines, isocyanates and other chemical fumes. In 2013, the Canadian Broadcasting Corporation reported on homeowners who had to abandon their home after it was insulated with spray foam because it made them so sick. Around the same time in the U.S., an “avalanche” of similar health complaints and court cases cropped up against spray foam manufacturers.

According to 2013 testimony to the General Law Committee of Connecticut from a homeowner, the spray foam installed in his 1890s home shrunk, cracked, gave off a strong noxious odor and even exploded in the middle of the night. He was never warned about the health effects, even while his family lived in the house during remediation, when spray foam dust filled his home.

Once people are exposed to a high amount of isocyanates, they may become sensitized, meaning even a tiny bit of exposure — like walking into a building with spray foam insulation or buying a memory foam mattress — could trigger asthma. This is particularly a problem for spray foam installers.

“Isocyanates have been reported to be a leading attributable chemical cause of asthma in the workplace,” the EPA warns. “Even if you do not become sensitized to isocyanates, they may still irritate your skin and lungs, and many years of exposure may lead to permanent lung damage and respiratory problems.”

In 2016, a whistleblower lawsuit was filed on behalf of the U.S. government against four major manufacturers of spray foam chemicals — BASF Corporation, Bayer Material Science, Dow Chemical Company and Huntsman International, which had bought the spray foam manufacturer Icynene. It alleged that the companies knew of the serious health effects of isocyanates and kept that information from the EPA. The case did not move forward.

While failures to cure are immediately apparent, another danger that only presents itself many years later is that the spray foam doesn’t actually create the airtight seal promised, which can lead to air quality complaints and devastating structural problems.

One Kansas City builder, Travis Brungardt, has documented for The Journal of Light Construction every type of failure in spray foam, even when working with reputable local installers: improperly cured foam; voids, which are akin to air bubbles or caves within the foam; gaps, which reveal the sheathing or decking; the foam “delaminating,” or pulling away from the wood; and even failure to achieve the thickness that would provide the insulating value promised.

“While I believe spray foam can be a path to success, I haven’t seen it executed successfully in my market, and I will avoid that risk whenever I can,” Brungardt wrote last June in The Journal of Light Construction

When you look online for Vermont spray foam experts, Peter Yost’s name is one of the first to come up. A building consultant with more than 30 years of experience in contracting and building science, he recently moved from Brattleboro to Durham, New Hampshire, with an eye on retirement.

I thought he would fall in the spray foam supporter camp, especially since he’s been hired by at least one spray foam company in the past, but his views on insulation are more nuanced.

“My mantra is: We have to manage energy and moisture with equal intensity,” he said. “If we just go after the energy and don’t recognize the moisture, we’re going to create problems.”

Houses always have a certain amount of water vapor in the air, which can come from wet basements, but also everyday necessities such as cooking, bathing, and even breathing and sweating.

In a house with little insulation, the escaping heat dries out the walls. Spray foam, as a plastic, is hydrophobic, so it air seals if applied perfectly. But if there are any pathways, cracks or voids, humid air can sneak in and hit the cold exterior framing, condensing into water. That water can then be trapped by the spray foam and settle in to rot the wood framing members.

Rot issues related to foam tend to show up around eight years after the initial application, according to Jim Bradley, founder of the building science consultancy Authenticated Building Performance Diagnostics in Cambridge. In fact, he had the roof of a new addition to his home spray foamed a little over eight years ago using what he thought were best practices at the time. That meant his roof was spray foamed, with no ventilation, making it what is called a “hot roof.”

Recently, he’s noticed “tea stains” dripping out of the soffits — where the roof overhangs the house’s exterior siding — and staining the drywall, indicating a wood rot problem.

“And it makes me sick, because this is my business,” Bradley said.

In 2005, a New Jersey couple sued both the foam manufacturer Icynene and the spray foam installer of their new vacation cabin in Warren, claiming the spray foam had caused extensive moisture damage. The case was settled with Icynene out of court in 2006, a week before it was set to go to a jury trial. (I contacted the spray foam installer, but the company is under new management and could not comment on the specifics of the case.)

“There are a lot of good spray foam contractors in Vermont that do good work and there are places where spray foam is perfect,” said West, the Passive House consultant. But, “When we go into an old house, we never spray foam.” (By “old” he means 1950s or older, but, he later clarified, he’s not a fan of it in any age home.)

There are only a handful of people across Vermont who can give unbiased and holistic consultations to homeowners about moisture management and weatherization together, according to Yost.

“We don’t have nearly enough building professionals that understand building science,” he said. “If you’re an existing building owner, it can be so complex. You need to make sure that you don’t have just an energy auditor looking at your building.”

Health complaints could also, ironically, arise because the home is too tight.

“What we find is if you go in and you spray an entire home, seal up that complete building envelope, you are not going to have enough natural ventilation to maintain good indoor air quality,” said Duncan, of the Spray Polyurethane Foam Alliance.

He and other building science experts I spoke to recommend homeowners install an air exchanger, equipment housed in the basement that circulates stale, moist air out while pulling in dry, fresh air.

If not, particulates from cooking, off-gassing from furniture and carpets, and other other indoor air pollution could build up and bring the home’s air quality to below a typical day in New York City. Add in the mold that can come from trapping moist air, and you’ve got yourself a health crisis in the making.

Government agencies have not tracked the prevalence of homes with mold in the U.S. or Vermont over time. But according to a 2022 NIOSH assessment, dampness and mold problems are estimated to affect 47% of U.S. homes.

Business has been swift in the past couple of years for mold remediation, according to Chuck Nystrom, a contractor and co-owner of Catamount Restoration Services in Manchester Center. He at least partly attributed the uptick in calls to homeowners tightening up the air flow in their homes. “A lot of people didn’t see mold for many years. Fifty years ago it wasn’t an issue. The homes breathed more,” he said.

One big problem Nystrom has seen is when the soffit vents are sealed up by foam. “So by changing the way a house breathes, you’re now trapping the moisture in,” he said. “And once it gets in, because (the house) is so efficient, the only way to get it out is to use a manmade device: a dehumidifier, an air exchanger, something of that nature.”

When asked his opinion of spray foam, Nystrom called it “a great product — if applied correctly.”

He noted that traditional insulation with rock wool or fiberglass is “easy enough” to undo if issues arise. But, he said, “Once you go spray foam, there is no going back.”

Spray foam permanently sticks to whatever it is sprayed on, and it can cover up and hide water leaks, mold and damage for years. For inspectors to view a home’s framing, the foam has to be chopped away. Complete removal is prohibitively expensive for most homeowners.

Everyone I spoke to agrees that spray foam is better suited for some jobs than others. Instead of the top of a home, look to its bottom, they said — particularly old rubble-walled foundations.

“That’s where spray foam really shows up as one of the best options available, without going to more heroic measures that can cost a lot more money,” said Racusin, New Frameworks’ building science director.

Unfortunately, as Yost points out, homeowners don’t get rebates for addressing their homes’ moisture problems. Without financial incentives, owners with lower incomes often cannot afford to solve water issues before they call in a spray foam installer.

It’s unique to each house, but West says $15,000 “is a pretty standard price” for basement remediation work to address water intrusion for a 2,000-square-foot house.

Some industry observers have raised questions about just how sustainable spray foam really is.

In 2007, licensed architect David Pill built his family a LEED Platinum house and Vermont’s first Net Zero home — meaning it generates as much energy as it consumes in a year — and used spray foam to insulate it.

“I can’t believe (LEED) let me use that. But at the time, nobody knew about spray foam,” Pill said.

Pill hasn’t used it in a project since, mainly because he doesn’t consider it a green product. Traditionally, spray foam has required a blowing agent with a global warming potential (a widely used measurement for emissions) of 1,000 or more. Spray foam manufacturers are moving to a blowing agent with a lower global warming potential of just five.

But because it’s made completely from fossil fuels, spray foam still arrives with a high amount of “embodied carbon,” meaning a lot of fossil fuels were used and a lot of greenhouse gas emissions were released before it is ever sprayed into a home.

According to a report by Efficiency Vermont released last summer, it would take about 10 years of energy savings for a home with spray foam insulation to match the carbon savings of a home with dense-pack cellulose and rigid foam board insulation. (That’s assuming a typical homeowner sticks with an oil furnace and makes no other changes.)

Unlike some green builders and experts, Efficiency Vermont does not currently consider embodied carbon in its recommendations to homeowners, Sharpe said.

“Our first and foremost mission is to reduce energy waste and save Vermonters energy and money,” he said.

Experts say that heat pumps, which efficiently condition outside air into hot or cool inside air depending on the season, cannot do their job in a very drafty, uninsulated house. But once you’re no longer primarily heating with oil, it doesn’t do much for the environment to stress over getting your house perfectly sealed — you might as well go with an alternative with a slightly lower R-value.

The report by Efficiency Vermont also assumes best practices for spray foam application.

“When you go ahead and build something, and it fails prematurely within five years, 10 years, and you’re replacing siding, roofing, whatever, how much more of an energy cost is that?” Bradley said. “This whole movement that we have for global warming initiatives and saving the planet and all this energy savings, we are missing the mark, especially in Vermont.”

The architect Pill’s spray foam application didn’t go well. He called the installation “completely wrong.” When he discovered gaps, voids and cracks several years later, he called the contractor who built the home, who told him the spray foam company was out of business.

Recently, Bradley and West stopped by and took a look at the spray foam in Pill’s attic and discovered many more gaps, plus areas where the foam is peeling away from the roof deck and areas of moisture. There’s no rot that they could see — Pill credits the plywood for being rot-resistant — but the gaps will have to be filled again … with more spray foam.

Crossman bought his grandparents’ modest 1950s timber-frame home in 2001 and spent the next 10 years steadily renovating it. Room by room, he tore out the walls down to the studs, and replaced the old batt insulation with new fiberglass batt insulation. By 2009, he was done with the first floor and ready to start the second.

At the time, Vermont Foam Insulation was on-site at a job Crossman was working on and he accepted a pitch from its sales representative, Will Reed, to insulate the entire top floor of Crossman’s home with open cell foam — the spongier, more affordable option with little air bubbles that are broken open.

The company did one side of the house in 2009 and came back to do the other side the following year. Crossman applied a vapor retarding primer paint as recommended.

“There was definitely a smell that first couple of years. I don’t know if we got used to it or if it just went away,” Crossman said. But he didn’t notice anything was really wrong until the winter of 2012, when moisture started building up on the windows. It got worse the next year.

“The bottom two inches of the sash on the glass in the mornings would be just drenched with water,” he recalled. “We’d have to go around wiping them down every morning.”

At the time, some people inside the spray foam industry were raising the alarm about shoddy workmanship. Henri Fennell, a Thetford-based spray foam consultant with 25 years of experience, wrote in The Journal of Light Construction that contractors who were out of work during the 2008 financial crisis had rushed into the growing spray foam field, bringing little experience with them and pushing prices down to unsustainable levels.

“The ongoing price wars have also been accompanied by a pronounced increase in bad installations. Industry experts tell me they’ve seen more foam quality problems in the last two years than in the preceding two decades,” Fennell wrote.

Part of Crossman’s problem might also have had to do with the choice to use open cell foam, which Crossman said was pitched to him as a way to identify leaks should they happen.

Rick Duncan, executive director of the Spray Polyurethane Foam Alliance, confirmed that leak detection was a common marketing point 10 years ago, though he doesn’t believe it is true.

“You don’t always see a leak developed right below where the hole is on the roof,” he said. “You never know where that water is going to come out. It can actually be retained in the open cell foam like a sponge, and then it can drain out towards the soffit and come down the walls.”

He said open cell foam is fine as long as you use a vapor retarder, including paint, like Crossman did. But he acknowledges the models used to support this recommendation are based on ideal conditions and perfect application.

Vermont Foam Insulation declined to comment on Crossman’s case. Reed, the sales representative who worked with Crossman, said the company still uses open cell foam, though he wrote in an email that the company installs more closed cell foam today.

In 2012, Crossman called Reed, who told him that he would have to install an air exchanger at a cost of $5,000, according to Crossman. It did seem to mostly fix the moisture problems, until eight years later when he discovered his roof had dry-rotted.

First, he called Efficiency Vermont, who sent someone out to take a look. Crossman said he was told the insulation had been done wrong and to call Vermont Foam Insulation.

Dissatisfied with the quality of the company’s work, Crossman had stopped bringing Vermont Foam Insulation into his projects years before. But he called up the company, and owner Joe Thompson came to check out the problem. (When I reached out to the company asking to speak to Thompson, I heard back from Reed.)

As Crossman tells it, Thompson peered into the walls and told him, “You’ve definitely got a problem but it’s not as bad as you think.” Thompson contended the wood stove or the moist basement could be to blame, Crossman said, and suggested spray foaming the latter. Finally, Thompson offered to pay for Yost to come take a look.

Yost later performed a blower door test and a smoke test, during which a house is filled with theatrical smoke to identify air leakage. “And what I remember is that there were significant (air leaks) that the spray foam was not addressing,” Yost said.

He recommends that these tests be done immediately after any insulation is installed. Crossman says a moisture assessment before the installation in 2009 and blower door test after in 2012 did not happen.

Reed, of Vermont Foam, said in an email that “almost all of our retrofits get a pre and post blower door.”

“We are slowly adopting blower door testing for new construction projects,” he wrote. “We agree with, and promote this measure, particularly with regard to its adoption into the building code.”

Without commenting on Crossman’s case, Reed said that Vermont Foam Insulation advises customers to fix moisture issues before having spray foam installed, and also that it will recommend and install other forms of insulation when it’s appropriate.

“Spray foam is used to insulate buildings, not to repair water issues, preexisting moisture, or air flow issues,” Reed wrote. “You wouldn’t put a blanket on a leaky pipe and say that it’s fixed.”

Because Yost was paid by Vermont Foam, he couldn’t share his findings with Crossman. In any case, he said he didn’t come to a clear conclusion of fault.

“It was very difficult for me, because the spray foam that was done was done 10 years prior to my involvement. (It’s) very difficult to separate out what conditions were the result of a lack of perfection in the installation of the insulation, versus the existing moisture conditions in that building,” Yost said. “I don’t think either party was going to end up being particularly happy with what I was going to say.”

When asked how Vermont Foam Insulation recommends homeowners monitor their spray-foamed homes for leaks or damage, Reed wrote, “Homeowners need to work with their general contractor, HVAC provider, architect, or building science expert to ensure their home has no leaks or damage. As an insulation contractor, we are there to insulate, not provide an entire home review.”

Crossman couldn’t find a building science expert to advise or help him. After hunting high and low, he found a lawyer who would file a claim with Vermont Foam Insulation’s insurance company, Liberty Mutual, which forbade Crossman to do any work on the house until the claim was resolved.

So, after waiting some time, Crossman filed a lawsuit and got to work replacing the roof, plus many of the second-floor walls and windows of his home.

His lawsuit asked for $300,000 to cover materials, labor, renting another home, and other costs. It was sent into mediation, which dragged on for a year and a half. This winter, his lawyer advised him to settle with the insurance company for less than half of what he was asking.

Vermont Foam Insulation would only say that “a mutual agreement was reached and we did not accept liability.”

“I can’t even put into words how hard the past two years have been,” Crossman said.

If you don’t have the budget for an architect or high-end green contractor with a building science expert on staff, Efficiency Vermont has a hotline with trained customer support agents. If your questions get into more complicated territory, you’ll be referred to an engineering consultant such as Sharpe, and you can even have a virtual home energy visit. You can also contact one of the building science experts quoted in this story.

Racusin said that if you’re a homeowner looking to tighten up your house because you’re miserably cold and paying through the nose for heating oil, and you want to take advantage of the rebates and incentives, there are two places to focus.

First, insulate your basement (after you’ve solved for any water incursion or moisture issues). After that, complete some targeted air sealing via some caulk or tape in the attic, and finish it off with some dense-pack cellulose. That will go a long way to make you comfortable without taking unnecessary risks.

When you’re ready for a larger renovation project, you can visit Efficiency Vermont’s website to find contractors who have gone through the Building Performance Institute, or the Brattleboro-based Sustainable Energy Outreach Network for a list of members. Or, you can choose a contractor who is open to going through one of these certification programs.

If you’ve already spray-foamed your home, Duncan recommends getting a moisture meter with an alarm and putting it in your attic, plus having your roof inspected every five years. An inspector with an infrared camera can identify moisture issues, and there are now mini infrared cameras available that plug into your smartphone.

I feel lucky that I was nudged away from spray foam at the last minute and — through this story — have been able to ask the state’s foremost experts for advice on what to do. I paid almost double the usual fee to have Bradley drive three hours from northern Vermont to audit my home. His first recommendation? You guessed it: Fix my leaky basement.

Crossman joined us for part of the tour. Having experienced the downsides of poor weatherization, he is ready and eager to learn the ins and outs of building science alongside me as we set out on our home renovation.

But I’m just one person. Hopefully, for the sake of my neighbors down here in southern Vermont, there will be more contractors learning building science soon.

Otherwise, Vermonters are in for some nasty and expensive surprises, lurking right inside their walls.

Corrections: An earlier version of this story misstated the status of Efficiency Vermont’s partnership with Vermont Technical College to offer the Building Performance Institute, and understated the number of Vermont households that use fossil fuel to heat their homes. Additionally, the third-party voluntary certification program LEED doesn’t rule out spray foam as a way to achieve high energy efficiency. The story was incorrect on that point.

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