Is foam insulation evil?
Is foam insulation evil?
February 14, 2016 | by Floris Keverling Buisman, CEO/Technical Director, 475 High Performance Building Supply
Here at 475 High Performance Building Supply, we believe less is more when it comes to foam, especially in a high performance building enclosure. This is because, in short, foam fails. If our goal is to build with health, climate change, safety, energy efficiency, resiliency and reliability in mind, foam simply does not make the cut.
While we could go on for pages about the pitfalls of using a foam based building enclosure, we’ve summed it up into four main points:
1. Harmful to human health
In terms of considerations made when choosing building materials, their effect on human health should be at the top of the list—which brings us to why foam should be at the bottom of yours. Many of the chemicals used as ingredients and in the processing of foam have been labeled as toxins, carcinogens and endocrine disruptors. Spray foam contains ingredients so toxic that applicators must wear full body protection, including a gas mask. After application, continuous off-gassing of the materials can expose building occupants to harmful chemicals, significantly decreasing indoor air quality.
Reliability and longevity should be givens when it comes to an insulation and airtight material. Failed materials within enclosures can lead to serious problems relating to moisture, air leakage and level of indoor comfort. With spray foam, an amalgamation of potential problems sums up to an unacceptable product. First of all, the material’s on-site manufacture is hypersensitive. Its intolerance of adverse site conditions results in substandard finished applications. Inconsistencies in curing rates can result in weak and unpredictable air control. Even considering perfect application, the material is naturally inflexible and cracks. Additionally, as the material ages, excessive shrinkage and expansion can occur, placing stress on assembly connections and potentially allowing air leakages. What makes this especially problematic is the difficulty associated with identifying and subsequently repairing these air leaks. Lastly, moisture intrusion into the insulative layer can be just as much a concern. Being hydrophobic, spray foam does not actively help manage moisture intrusion. This quality also makes it a counterproductive vapor retarder/barrier, which can result in wet conditions under sheathing.
3. Fire hazard
The main ingredient in foam is polyurethane. Any petroleum based product is naturally a fire hazard. While spray foam does include fire retardant chemicals, these chemicals are not effective enough to prevent foam from igniting. Therefore, foam remains a fire accelerant. Foam feeds fires, reducing effective firefighting response times.
4. Negative climate effects
Being petroleum based, spray foam itself is made from one of the most unsustainable and polluting resources available. Additionally, standard closed-cell spray foam is produced with hydrofluorocarbon blowing agents. Even if a company claims to offset the effects of global warming by providing superb insulation, the high global warming potential inherent in the production of the material compromises the potential good.
Less is best
So in light of all this, you may be left asking, “Is foam evil?” Our answer is no, not exactly. We recognize the benefits of foam in limited applications such as structural thermal breaks and in architectural components. Nonetheless, we stand by the “less is best” principle and always push for foam-free construction. Believing that there are better solutions is at the core of our operations.
Airtight construction is the one of the central tenets of the high performance construction and the Passive House standard. An airtight envelope is easily achievable with a combination of fibrous insulation, membranes and tape. At 475 High Performance Building Supply, we provide a range of interior and exterior membranes and tapes that provide superior airtightness. Our exterior membranes are vapor open, weather resistant barriers that allow insulation to dry outwards, preventing moisture from building up in the insulative layer. On the inside, our interior membranes are intelligently vapor variable, with low permeability in the winter and high permeability in the summer, optimizing the drying capacity of the insulation. When used with our interior and exterior tapes, these membranes provide airtight enclosures. In order to ensure the highest performing building enclosure, we suggest using them in tandem with fibrous insulation such as fiberglass, cellulose or mineral wool. All three materials far surpass spray foam in the previously discussed categories of human health, fire resistance, effect on climate and reliability. When used with airtight membranes, a system is created that is durable, flexible and sustainable. These traits also translate into a more affordable option, as airtightness and insulation with a much lower fail rate will lead to lower energy bills.
The shift towards foam-free construction is growing fast. Over the last few years we’ve had the privilege of being a part of many projects that exemplify our core message and welcome the opportunity to help others do the same. Foam-free solutions are achievable for walls, roofs and even retrofits. The double stud wall is a particularly economical way to achieve high R-value assembly. Additionally, the unvented roof is one of the most common home features in the United States. As the Passive House movement grows through the U.S., deep energy retrofits are also becoming more common, especially in the coldest climate zones.
What is important to remember about the foam-free solution is that it works as a system. Fibrous insulation alone will not provide an airtight enclosure. Likewise, membranes alone will not provide adequate thermal comfort. However, together they create airtightness and thermal comfort that is unparalleled.
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