Grenfell Took Many Lives...Yet We Continue To Play With Fire
The same materials that caused industrial disasters are in your home too
Most homeowners are unaware that the foams and plastics that caused large disasters are widely prevalent in homes. If you like the post, please support me by sharing it.
After a few winters in a cold house, I began to wonder whether the walls had been insulated. Part of the house was still unfinished, so I knew it would be possible to insulate those areas. The professionals I had consulted told me to insulate primarily with mineral wool but recommended foam for a bathroom wall. This turned out to be a disastrous idea, as there had been water coming into the building, something I was unaware of at the time. The foam trapped the water, which then caused large amounts of mold to grow. The worst part of this was that we couldn’t see any mold as it was underneath the walls, and it would have been months before there were any visible indications.
At the time, I didn’t fully understand that foam is horrid stuff. I tried to fill a gap with spray foam once, and somehow it got on my hands. It was incredibly sticky and so tenacious that it took several days, many washings, and several different cleaners to remove it. I never wanted to use it again.
When I tried to find ways to insulate finished walls, the options were limited. The walls were plaster, and ideally, I wanted to insulate them without having to take them down. The two most readily available methods were spray foam and cellulose but cellulose installers were scarce. I was aware that foam insulation was responsible for the rapid spread of a fire in London where many people died. It was clearly a dangerous choice, one that I sought to avoid. Cellulose didn't seem to be the right insulation either, as it is treated with chemicals and can be problematic in homes that have water issues.
I struggled for several years trying to find a suitable and safer alternative that would not require removing walls. Due to faulty construction, some walls had to be taken down, and I was able to insulate them. The plaster walls continued to pose a challenge. My passive house contractor suggested that I use foam because he didn’t want to deal with the hassle of taking down a wall. I was frustrated by this, as his qualifications were the reason that I had hired him. I am by no means a stickler. Sometimes small amounts of foam are the easiest way to plug holes or seal air gaps, and it’s a good option for below-grade applications. But after I had read more articles about the Grenfell fire and studies about foam, I drew the line at using it extensively. Here’s why.
Some of you may already be familiar with the Grenfell Tower tragedy that occurred in London in 2017. Seventy-two people died in the 24-story residential tower due to a fire. Many of the occupants were from low- and moderate-income working-class families.1 Fast, cheap, and shoddy building practices often find kinship in inequality, broken housing, and racism, a paradigm for modern social themes.
“We learned about the shocking lack of knowledge and regard for safety among the architects, builders and specialist contractors involved in the 2015-16 refurbishment of the tower. A decision was taken by this team to switch the building’s cladding from zinc to plastic-filled aluminium composite material (ACM) to cut costs.” - Lucie Heath, the Guardian2
A flawed cladding made of foam
I don’t care for some types of brutalist architecture, and the tower, designed in 1967, fell squarely in the ugly camp. In any event, when it was built, the tower’s design was considered innovative. Why? Instead of traditional brick infill, pre-cast insulated panels with polyiso were used. When the tower was renovated in 2012 and 2016, a highly combustible cladding of aluminum panels with a polyethylene core was installed. The tower also had 10 columns, several on each face — an uncommon and flawed configuration. In a typical building, fire will travel towards oxygen, i.e., towards windows, and if you live in a masonry structure, it will not burn as quickly. With Grenfell, the wall panels allowed the fire to move laterally while the paneled columns enabled it to rapidly ascend. As a result, the fire was able to engulf the building in a short period of time. Seemingly innocuous design elements can sometimes have cruel and fatal consequences.
In a report to the Grenfell Public Inquiry, fire safety engineer Dr Barbara Lane identified the fire spreading vertically up the tower columns, and "laterally along the cladding above and below the window lines (and) the panels between windows." - The BBC
The materials used in Grenfell are in many building products, including residential foam insulation.
It has been widely reported now that the wall assembly in Grenfell included Reynobond PE (a polyethylene core between sheets of aluminum) on the outside and Celotex RS5000 PIR (polyisocyanurate or polyiso) on the inside. PUR (polyurethane) was also present. All three are polymers. Polymers are substances made of large molecules formed by joining smaller molecules together. Plastic polymers are often used in construction because they are strong yet lightweight.
Polyethylene
Polyethylene is the most widely used plastic in the world. Examples include detergent bottles, food wrap, cereal box liners etc. While generally considered safe in these forms, heat and sunshine can cause the leaching of antimony or estrogenic chemicals that pose health risks.
Antimony (Sb) is a chemical element that can cause problems with the lungs, heart, and stomach. Estrogenic chemicals have adverse health effects on humans especially in the fetal stages.3
Polyethylene is very easily ignited. It has the same composition as gasoline, so it burns ferociously, and when it does, it releases a lot of high heat.4As in Grenfell, PE is sometimes used in conjunction with polyurethane.
Polyiso and Polyurethane
Polyiso is a plastic that is commonly used in 70% of roofs as rigid foam insulation or as a protective layer. Polyurethane is similar, except it’s more flexible. Three-quarters of the world’s production of polyurethane is in the form of foam. Think furniture and automotive upholstery, mattresses, spandex, MDF binders, spray foam insulation etc. Polyiso and polyurethane are created by reacting polyol (a kind of alcohol) with isocyanates in the presence of catalysts and additives. Polyiso has more isocyanates than polyurethane.
Isocyanate toxicity has been widely documented
Isocyanates are organic compounds typically made up of NCO (nitrogen, carbon and oxygen). Isocyanates are toxic and are well known to cause irritation of the eye, the gastrointestinal tract, and respiratory systems. They were the main culprit in the world’s worst industrial disaster, that happened about 40 years ago at the Union Carbide plant in Bhopal.5 600,000 people were exposed to methyl isocyanate causing them to suffer from ailments such as blindness and breathing difficulties. 15,000 people died. The exposures also led to the birth of mentally and physically disabled children, and hazardous waste was left in the soil, leaching chemicals for years afterward.
Foam insulation continues to be popular and widely used.
There are a number of buildings in the UK and the US that still have combustible cladding. After the Grenfell fire, the UK government launched a fire safety review of almost 600 blocks that had cladding similar to Grenfell.6 In the United States, foam insulation is increasingly common and gaining popularity.
Most foams come in a flexible or rigid form:
Sprayed or poured in place:
polyisocyanurate, polyurethane, cementitious, and phenolic
Rigid foams (boards):
polystyrene, polyisocyanurate, polyurethane, and phenolic
Out of all of these, cementitious foam is the only one that is non-toxic. Often branded as "Air-Krete", it is made of magnesium oxide (from seawater), calcium (from ceramic talc), and silicate. You've probably seen Air-Krete in advertisements for eco resorts. It can be used for insulation but can shrink over time and installers are not easily found.
All the other foams burn rapidly, produce extreme heat and dense smoke. The combustion is additive, so a greater number of plastics in a building also means increased toxicity. Polyiso, phenolic, and polyurethane are the worst offenders. In addition to carbon monoxide, they release large amounts of nitrogen and cyanides.7 In most fires, people die of inhalation and studies have correlated inhalation deaths directly to building materials that release cyanide.8
Insulation manufacturers and installers claim that foam is fairly safe.
All foam, whether spray foam or boards (often used in basements, floors, and roofs), is fire rated. Spray foam insulation, which is typically polyurethane, has a “Class 1 hour fire rating.” This means that the material can resist a typical fire for an hour. A smaller residential building is unlikely to burn like Grenfell. However, fire experts say that you only have a few minutes to escape a fire due to the types of building materials and synthetics in homes. So why take an extremely dangerous risk?
I am distrustful of safety claims and ratings. Most of the sites that claim foam is safe were either created by manufacturers or installers. With Grenfell, it was discovered that the safety testing was flawed and the manufacturers were dishonest. Testing is often conducted in isolated conditions that are far different from the real world, so we may never understand the actual behavior of a material that catches fire until something catastrophic occurs.
Spray foam and rigid foam manufacturers will tell you that foam creates an air- and vapor-tight building, that it is an excellent insulator, and that the toxicity is overblown. Foam is indeed an effective air barrier and a good insulator, but there are other products that are as effective and much safer. In addition to being extremely dangerous in a fire, foam based building products can be problematic in other ways.
Foam can off-gas and/or smell for months9. It has a negative impact on indoor air quality and can cause breathing problems and other adverse health effects.
Foam is unsuitable for use in a masonry building. Brick and mortar are porous. If you have an airtight foam layer on the inside, it will make the outside bricks colder. Cold bricks are wetter, and the foam has now blocked the warm air that would drive the moisture out. This can cause wet bricks to freeze and thaw, a cycle that damages the masonry over time.
If water manages to find its way between foam and masonry or wood, the foam can trap moisture and encourage mold or cause rot.
Foam is derived from petroleum which makes it unsustainable.
Foam is extremely difficult to remove once it adheres to something. This means that the product cannot be recycled and must be thrown away, cluttering landfills.
When spray foam is installed, hydrocarbons are used as blowing agents, which are responsible for global warming.
If the spray foam installer misses certain areas, there may be areas where humid air can condense and cause moisture problems.
Spray foam can shrink over time, defeating the purpose of insulation.
Local government policies favor foam because of its high R-value and widespread availability of installers.
In partnership with the state government, National Grid, a local gas company in New York has an energy incentive program. In order to receive a rebate, customers need to insulate their walls at least R49. For reference, a summary of the program can be found here.
An R-value of 49 can be achieved either through 7” of closed-cell spray foam or about 12” of mineral wool or cellulose. Since foam provides more insulation with less material and walls won’t need opening, it can be the cheapest option.
A Google search for insulation providers in New York City displayed 12 providers near me. Every single one was a foam installer barring one or two who installed cellulose as well.
Most customers will pick the cheapest and most convenient insulation option. When I called foam installers, most said they were unwilling or unable to install alternative materials, even though I offered to source the material and they only had to provide the labor and equipment. They said it was easier and faster for them to install foam. One of the installers told me that while he regularly installs foam, he would never put it in his own home.
It is a discouraging situation, one created by a lack of awareness combined with spurious marketing from foam manufacturers and poor policy. When governments create energy policies with incentives for insulation, it sets a poor precedent when unsustainable choices are incentivized at the same rate as sustainable ones. We also do not know what impact these materials will have in the years to come.
At least in my situation, I finally succeeded.
At the end, my perseverance paid off. After failing several times, I was able to insulate my walls without having to take them down. I feel fortunate that I was able to use a natural material. The entire process was much more challenging than I had anticipated and more difficult than it needed to be. Better government policy may have increased the availability of safe and sustainable insulation alternatives. To be continued…
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