The Great Debate: Pros and Cons of Spray Foam Insulation

January 12, 2022

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5 min read

In my previous article, we explored the differences between open and closed cell polyurethane spray foam, delving into their chemical compositions, physical properties, and overall performance. Today, we will dive into the pros and cons of both types of spray foam, addressing your feedback and answering questions from the previous video.

Advantages of Spray Foam Insulation

High R-Value: Spray foam offers excellent resistance to heat flow, commonly measured as R-value. Closed cell foam boasts an outstanding R-value of 6 per inch, while open cell foam still performs admirably at 3.5 per inch. Additionally, spray foam’s air sealing properties enhance its effectiveness against all three forms of heat transfer: conduction, convection, and radiation.
Air Sealing: With just 1 to 1.5 inches of closed cell foam or 3 to 3.5 inches of open cell foam, an air barrier can be achieved. Properly applied spray foam can improve indoor air quality by sealing gaps, preventing the infiltration of moisture, allergens, and airborne contaminants. It effectively stops uncontrolled air leakage, the primary cause of energy loss.
Energy Savings: Spray foam insulation can lead to significant reductions in utility bills by maintaining conditioned air within the building. Estimates suggest it could lower heating and cooling costs by up to 40%. Furthermore, it is considered eco-friendly for reducing energy consumption, greenhouse gas emissions, and HVAC requirements.
Closed Cell Foam Benefits: Closed cell foam offers impermeability to water, providing protection to attics and crawl spaces against moisture. It enhances the structural integrity of exterior walls, increasing resistance to compression and shearing forces. This makes it particularly advantageous in areas prone to severe weather conditions.
Long Lifespan: Spray foam boasts a lifespan of up to 80 years, with minimal thermal drift or loss of R-value over time compared to traditional insulation. It does not sag, settle, or deteriorate and is expected to outlast the building’s life. Moreover, spray foam does not serve as a food source for pests, rodents, mold, mildew, or bacteria.
Constant Evolution: The spray foam industry continuously evolves, spurred by constant scrutiny. It has transitioned away from using greenhouse gases like CFCs and HCFCs, significantly reducing environmental impact. Modern open cell foam utilizes water as a blowing agent, while closed cell foam adopts a low global warming potential chemical.

Disadvantages of Spray Foam Insulation

High Upfront Cost: Spray foam insulation comes with a substantial initial cost, approximately three times more expensive than traditional fiberglass insulation. Costs have fluctuated due to raw material shortages and supply chain issues, ranging from 50 cents to 1 dollar per board foot for open cell foam and $1.5 to $3 for closed cell foam. However, energy savings can lead to a payback in less than 5 years.
Limited Sound Insulation: While open cell foam offers some soundproofing potential due to its high air content, it does not match expectations. Soundwaves can be trapped, creating resonating chambers that amplify mid-range frequencies, causing disruption. The hardened foam also couples wall elements, increasing sound transfer. The STC and NRC ratings of spray foam are lower than rockwool or fiberglass.
Insufficient R-Value for Some Cases: R-value tests, which favor fibrous insulation, may lead to spray foam not meeting minimum code requirements. In some situations, installing 4 inches of open cell foam on the roof and 3 inches in exterior walls might not be enough.
Thermal Bridging: Applying spray foam solely between studs without continuous insulation on the building’s exterior can lead to thermal bridging, reducing the overall wall assembly’s performance.
Permanence: Proper scheduling is vital when using spray foam, as it must be applied after electrical and plumbing work. Once in place, changes are nearly impossible, and renovations to the building’s structure become exceedingly challenging.
Environmental Impact: As a plastic material, spray foam is non-biodegradable and will eventually end up in landfills. While its longevity and benefits during its life are significant, it raises concerns about environmental implications.
Fire Resistance: While both open and closed cell spray foam have flame retardant chemicals, they are not inherently fire-resistant. Though they char and burn, the flame extinguishes when removed.
Building System Impact: Replacing one component of a building can affect other elements. Existing homes may not be designed to take advantage of spray foam’s qualities, leading to challenges in accommodating gas furnaces, fireplaces, or water heaters in sealed attics.
Health Risks: Proper personal protective equipment (PPE) is essential when using spray foam. Exposure before complete curing can result in asthma, lung damage, breathing problems, and skin and eye irritation.
Meticulous Preparation Required: Spray foam is a finicky product that demands meticulous preparation. Substrate dryness and avoidance of contaminants are crucial for successful application. Technique is also essential to achieve optimal results without overspraying or underspraying.
Ratio and Speed Considerations: The ratio of raw materials is critical for proper foam properties. An incorrect mixing ratio can lead to structural issues and incorrect density. The speed of reaction also affects foam quality.
Not DIY Friendly: Spray foam is not suitable for DIY projects, as it requires expertise and precision. Novices may find it messy and challenging to get right, and using subpar products may lead to performance issues.

Conclusion

In conclusion, spray foam insulation presents several advantages and disadvantages, making it suitable for specific situations. It is vital to consider long-term building performance and consult with experts to determine if spray foam is the right choice for your needs. Though the product has faced scrutiny, it continues to evolve, promising a bright future in the construction industry.