Blog Post

Massachusetts Fires Tied to Spray Foam Incite Debate

As Massachusetts investigates the causes of three house fires that ignited while insulation contractors were installing spray polyurethane foam (SPF), observers ask if SPF is being demonized.

Fire investigators suspect that a fire that destroyed a $5 million home in Woods Hole, Massachusetts, was ignited in connection with a SPF installation process.

Photo: Dave Curran
As an insulation product, spray polyurethane foam (SPF) has many great attributes that we've talked about on this website: easy installation in irregular locations, air barrier qualities, and moisture management potential. Our publications and blog have also been active in covering some of the downsides of this product, including toxic emissions for workers and occupants under investigation by the EPA and the high global-warming potential of SPF. We have also been publishing a series of reflections by a builder who strongly favors more natural, breathable materials like cellulose.

But when SPF is implicated in building fires, it really turns my head! We're talking not about more vague, statistical likelihoods of future risks--we are talking about lives and property being endangered or lost in the moment. We wrote about that last year in the context of an effort by a fire marshals group to get the word out about unique fire risks from green building. That article referred to the tragic fire at the Alstonvale Net Zero House in Hudson, Québec, which occurred immediately after SPF installation, and reduced an almost-completed home to rubble.

Now the heat is on again: as our friend Martin Holladay at has written, three Massachusetts home fires have been linked to SPF installation:

The Massachusetts Division of Fire Safety (DFS) is investigating the causes of three house fires that were ignited while insulation contractors were installing spray polyurethane foam. According to Tim Rodrique, the director of the DFS, investigators suspect that the fires were caused by the exothermic reaction that results from the mixing of the two chemicals used to make spray foam.

One of the fires destroyed a $5 million home on the exclusive Penzance Point peninsula in Woods Hole on February 10, 2011.


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The house was being renovated at the time. According to the Cape Cod Times, "firefighters were somewhat stymied due to spray-on foam insulation. ... Similar insulation has proven deadly in the past. In 2008, Robert Cowhey of Springfield was spraying soy-based foam insulation in the attic of a North Falmouth home. The chemicals were located in a truck outside the home in two 50-gallon tanks, but somehow they ignited and Cowhey died in the ensuing fire."

Robert Cowhey, the victim who died in the North Falmouth fire, worked for Green Mountain Insulation of White River Junction, Vermont. Cowhey was installing SoyTherm50 spray foam insulation when the fire broke out.

When SPF is being installed, an exothermic (heat-producing) chemical reaction occurs. That reaction continues for some hours after installation is complete. If this heat doesn't have a way to escape from the foam, there is a risk that the foam could spontaneously combust. Foam contractors manage this risk primarily by limiting the thickness of SPF that is installed in one pass, to about two inches. In hot, stuffy attics, ventilation with fans may also play a role--or at least the absence of ventilation may have played a role in the Alstonvale fire. Holladay's article goes on to note:

On July 1, 2011, Stephen D. Coan, the Massachusetts State Fire Marshal, issued a memorandum to the heads of every fire department in the state. The memo notes, "Recently, the Department of Fire Services, Division of Fire Safety, has become aware of a number of fires involving commercially available spray-on foam insulation. At least 3 fires, one being a fatal fire, are believed to have been started during the application of spray foam insulation, and currently remain under investigation. ...

"Information gathered by the Division of Fire Safety from different manufacturers indicate that there are several possible scenarios that could lead to a heat build-up, and a possible fire scenario. These are: improper application techniques (excessive thickness, or spraying new material into the already applied rising foam) and/or improper mixtures of the chemicals at the application nozzle.

"Based upon this information, the Division of Fire Safety is recommending that you work with your building officials to determine if such applications are taking place within your community and, if so, to also make contractors in your communities aware of this potential fire hazard and encourage that they follow application instructions accurately."

The many comments on this article produce both light and heat at times. Paul Dion writes:

Let us all not all go off the deep end here and make spray foam the green industry punching bag. This case again speaks to error in the installation process. Sprayed in place foam when used in accordance to factory standards by trained applicators that care, is safe. I see the potential however for more of this bad press for foam as a new generation of not so committed foam applicators are buying equipment and doing things with spray foam that should not be done. This is an emerging building product in our industry and is growing faster in popularity than it can be regulated.

Sevag Pogharian, the architect and owner of the Alstonvale house, apparently has turned against SPF since that fire:

Homeowners and architects are seduced by the R-value of high-density polyurethane without sufficiently understanding or considering the risks associated with this product. As an architect and developer, I paid a very high price for this seduction.

Pogharian goes on to note reasons that we should avoid SPF. Several commenters, including Andrew Cole, take the other position:

In Canada, we install millions of kilograms of spray foam a year. As a member of CUFCA we track our work on daily worksheets that are submitted to our association. We have a great Site Quality Assurance Program that involves site testing, and recording on each and every job. The occurrences of fires directly linked to foam are few and far between and those that do occur, are usually traceable to operator error. I am not saying that this is acceptable. Clearly our industry has to do more to educate installers. But we also need a process aligned with inspectors to get the unqualified people out of the business. As in any industry we will always have issues surrounding competency. There are very good, very competent contractors and there are those that are not. But to discredit all of the good that 2lb. Closed Cell SPF can do due is really not acceptable. Plane crashes are a horrific tragedy, yet we continue to fly.

What do you think? Have you installed, spec'd, or been in a building using SPF? What was your experience?

Photo credit: Dave Curran Caption: Fire investigators suspect that a fire that destroyed a $5 million home in Woods Hole, Massachusetts, was ignited in connection with a SPF installation process.

Published July 14, 2011

(2011, July 14). Massachusetts Fires Tied to Spray Foam Incite Debate. Retrieved from

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November 11, 2014 - 9:16 am

I know that this article is from 2011 but I thought you might be interested in this article from this year (2014)

It is very unfortunate, but I honestly think more research needs to be done with this foam. It can be very dangerous and deadly.

July 26, 2011 - 6:57 am

I am an architect and recently used spray foam insulation on my own home addition/renovation.
Very easy to install, no heat problems, and this was the first time I did this type of work.
Read directions, work slow & careful, and use gloves, tyvek suit with hood, mask & goggles.
Spray back on work overhead is terrible.

July 22, 2011 - 3:57 pm

f.j.n., we aren't talking about a random occurrence here... we are talking about SPF installations that are probably too thick, installed by people who perhaps don't know what they're doing, who are from what we can tell needlessly burning down perfectly good houses. People are aware of electrical and plumbing risks, why not at least allow them to be aware of SPF risks so that if they choose to use this product they can get the right people on the job? Nobody's talking about government here... just knowledge and training.

July 22, 2011 - 12:55 pm

There is danger in anythig one can think of doing. How about crossing the street ? I have a great idea let"s get the government involved. Come on people use some common sense. These few homes are a drop in the bucket compared to all the buildings this product has been used in. Debating this topic in this forum seems almost futile.

July 16, 2011 - 2:10 am

It's clear to me that SPI should only be used in open cavity walls before sheetrock, as this would allow the heat to escape. It would be a shame to ban this product for worker error.

July 14, 2011 - 9:57 pm

It's unfortunate that such a useful product can be a potential hazard.

July 15, 2011 - 4:41 am

Let's get a few things straight about PU foam:
1. It's the exothermic bit of the chemical reaction that causes the two liquid components to foam up when mixed.
2. That reaction creates the basic C-N chemical bond characteristic of the urethanes: the same cyanide bond that produces toxic gases when the stuff burns in a fire.
3. PU foam doesn't like sunlight. It must always be protected from it, otherwise it just crumbles to dust.
That said, the stuff has been used all over the world for many years with few unfortunate consequences.
It is clear to me that the possibility of exothermic heat accumulating and causing a fire during installation if the material is applied too thickly and/or in an enclosed space is very high. However, when using PU foam to fill the cavity between inner and outer leaves of the typical British brick wall another problem occurs (related to the moisture movement mentioned in a recent BuildingGreen article). The foam seals the cavity, preventing upward air flow removing dampness from the outer leaf after wet weather. If it then freezes, the formation of ice within the bricks of the outer skin causes spalling of the outside brick face - to the extent that many people who paid to have their cavity walls filled with PU foam, to save on their oil central heating bills, found themselves having to pay a lot more for replacement of the damaged brickwork.
Just another case of unintended consequences.

July 21, 2011 - 6:24 am

As the designer/builder/consultant mentioned at the start of this article who strongly favors natural insulation materials like cellulose, let me note that improper cellulose installation can also cause building fires, though so rarely it's not statistically significant.

I know because, as a firefighter, I watched a local convenience store burn three times. After the original store was destroyed by fire of unknown origin, a new design was erected to be the prototype for all future stores of this locally-owned Vermont company. The night after the cellulose was blown into the suspended acoustic ceiling, the almost-completed new store burnt to the ground with the roof caving in and collapsing the building. It was ruled an electrical fire.

After all insurance claims were settled, the owners began construction again and had the same insulation contractor (now out of business) blow the ceiling. Fortunately this time, the operator of the truck-mounted cellulose blowing machine noticed some smoke in his hopper, stopped the blow and emptied the hopper. He found some charred cellulose at the bottom of the hopper, which was much too close to the overheated muffler from the compressor underneath. The paint at that part of the hopper was charred and should have been a tell-tale sign.

The GC immediately called the fire department to respond with a tanker truck and called in a septic pumper to suck out all the cellulose in the ceiling (which required the water from the tanker truck to keep the pump lubricated). I was the firefighter who examined the charred cellulose on the ground and bagged it up to give to the fire marshal who, this time, ruled this incident and the last fire to be caused by a faulty insulation blower.

While cellulose with borate fire retardant doesn't burn or support combustion, it's possible to get it sufficiently charred – like glowing charcoal – to combust adjacent flammable materials. Such an occurrence would be an aberration because cellulose insulates so well that you can melt a copper penny on top of 2" of cellulose in your hand with a blow-torch without feeling the heat.

But cellulose is a very different material than SPF. While both require some training and competence to insure a proper installation, shredded newsprint with boric acid is non-toxic to humans at every stage (a dust mask is recommended during installation). But the two-part chemical reaction of SPF is toxic during installation, in some cases has remained toxic for days to months and forced homeowners to abandon their homes, and in a few cases has initiated structure fires, sometimes deadly.

The SPF industry has taken an industrial, chemical process that works quite well in the controlled setting of a highly-regulated factory with in-house and outside safety specialists monitoring the process – and set it loose in the field in an uncontrolled environment, with far less consistent applicator training and an impossibly difficult arena for safety monitoring. A significant increase in application errors is to be expected. The question that the green building industry has to answer is: Are the perceived benefits worth the additional risks. The jury is still out.

July 14, 2011 - 12:29 pm

This is YELLOW JOURNALISM - should strive to provide unbiased information to its readers.

July 14, 2011 - 11:14 am

Oh no! As a Performance Green Building Consultant I was very upset when I read this article about the possibility that the installation of Spray Foam Insulation (SFI) has caused fires.
I’ve steered many of my clients to use this amazing system/material and can only report 100% satisfaction and accolades. I’ve consulted on many residential, commercial and public projects where SFI became an integral part of creating sustainable buildings. No matter the manufacturer, type, open or closed cell, SFI is an important tool in helping us all create sustainable buildings.
In what I’ve read it ‘seems’ the exothermic reaction ‘may’ be to blame. But the article states no ‘conclusive’ evidence. So before this escalates to become a myth, let’s please not over react.
If it the exothermic reaction is to blame, let’s ensure, as the article contributors state, that SFI is installed by a trained ‘certified’ installer with proper safety measures adhered to. Manufacturers shouldn’t sell their product to anyone but. Manufacturers should also be working towards developing products that minimize or eliminate such a chemical reaction.
GreenGary OK and FL

July 14, 2011 - 12:36 pm

Dear Interested Party, please explain what you mean.

We at pride ourselves on providing unbiased information. The article above basically consists of links to several previous articles on SPF, and quotes from various people who have different perspectives on this fire-safety issue relative to SPF. We quote three people (four if you include Martin's article). Of those four, two are articulately pro-SPF, one is simply reporting the facts (Martin), and one is anti-SPF, and we note a reason for his bias.

The gist of this article is that a debate is going on and folks in the industry should be aware of it. I hope this is a useful service to our readers. Any other opinions?

July 14, 2011 - 2:55 pm

Interesting article. I was not aware of the exothermic effect and am very glad to learn of it. I am involved with projects from time to time where this type of product is used, and this is the first I have heard of this sort of problem. The advantages of this product are numerous, from a building envelope standpoint and I don't think knee-jerk reactions are the answer to resolving this particular issue. I agree with Andrew Cole that proper education of the installers is of the essence, and tracking of the product's use through the manfacturer with some sort of pre-qualification process (other than "give me your money and your qualified") is necessary.

I have been considering its use in my own home, and will still consider the product, but will take pains to interview the installers before allowing them to proceed.