Is Spray Foam Insulation Safe? An Expert Guide to Health and Safety Facts
Did you know that some insurance companies are now refusing to provide building insurance for homes with spray foam insulation? This troubling trend extends to mortgage lenders who increasingly reject properties with this type of insulation.
Spray foam insulation can slash energy bills by 20-30% annually, but the safety concerns surrounding it have grown significantly. The Royal Institution of Chartered Surveyors (RICS) warns that improper installation not only tanks property values but creates serious structural problems through condensation issues.
Safety worries go far beyond your home's market value. During installation, spray foam releases volatile organic compounds (VOCs) that force residents to leave their homes temporarily. Questions continue to swirl about long-term health effects, pet safety, and the time needed for proper curing even after installation is complete.
This guide digs into the essential safety aspects of spray foam insulation – from the risks during installation to potential long-term health impacts. Whether you're considering this insulation for your home or wondering about existing spray foam, you'll find the facts you need to make smart decisions about this controversial option.
Understanding Spray Foam Insulation Composition
Spray foam insulation consists of a complex mixture of chemicals that react together to create an effective thermal barrier. Understanding these components is essential for assessing whether this insulation method is right for your home.
Chemical components and their safety profiles
Spray polyurethane foam (SPF) insulation forms through a chemical reaction between two main components, commonly called Side A and Side B. Side A contains highly reactive chemicals known as isocyanates, primarily methylene diphenyl diisocyanate (MDI) and polymeric MDI. Side B contains polyols (which react with isocyanates to create polyurethane), catalysts, flame retardants, blowing agents, and surfactants.
The chemical reaction between these components generates heat through an exothermic process. This reaction creates potential health risks, especially from isocyanates, which can cause skin, eye, and lung irritation, asthma, and chemical sensitization when absorbed through the skin or inhaled.
Furthermore, the installation process can release volatile organic compounds (VOCs) that may include formaldehyde, a known irritant and carcinogen. Consequently, proper protection is crucial for anyone present during installation.
Differences between open-cell and closed-cell safety considerations
The two primary types of spray foam insulation—open-cell and closed-cell—have different structures that affect their safety profiles:
Both types contain petroleum-based chemicals, though some manufacturers have developed "greener" formulas incorporating soy or castor oil-derived resins. Nevertheless, the installation hazards remain similar regardless of type.
Specifically, closed-cell foam requires longer curing times before reoccupation is safe. Additionally, its higher density means more materials are used during installation, potentially resulting in greater chemical exposure.
Industry safety standards and regulations in Canada
Canadian regulations maintain strict standards governing spray foam installation and safety. According to the National Building Code, medium-density spray-applied polyurethane must comply with CAN/ULC-S705.1 (Material Requirements) and CAN/ULC-S705.2 (Installation Requirements).
The CAN/ULC-S705.1-18 standard evaluates numerous performance criteria including long-term thermal resistance (LTTR), dimensional stability, water absorption, and air permeance. These standards ensure consistent safety and performance across all products on the market.
Moreover, Canadian regulations require installers to undergo specific training and certification. Caliber, Canada's largest certification body for spray foam, provides a quality assurance program that complies with industry codes and standards. Certified installers must be evaluated through practical examinations conducted by third parties, with certification renewal required every five years.
All spray foam installations require certain ventilation protocols and protective equipment for installers. Typically, manufacturers recommend a 24-hour waiting period after application before worker re-entry without protective equipment, though this may vary based on product formulation.
These comprehensive standards help mitigate the inherent chemical risks of spray foam insulation, providing a framework to ensure safety throughout installation and beyond.
Health Concerns During Installation
The installation phase presents the most significant health risks in the spray foam insulation lifecycle. During application, a complex chemical reaction occurs, releasing potentially hazardous substances that require strict safety protocols.
Immediate exposure risks for installers
Installers face serious health hazards when working with spray polyurethane foam (SPF) components. Research data indicates that inhalation exposures during SPF application typically exceed Occupational Safety and Health Administration (OSHA) occupational exposure limits. The A-side chemicals containing isocyanates present particularly severe risks, including:
Respiratory tract sensitization leading to asthma with symptoms like chest tightness, shortness of breath, and wheezing
Skin irritation and sensitization, causing reddening, itching, and rash
Eye irritation resulting in reddening, tearing, and stinging
Notably, even skin contact alone may lead to respiratory sensitization. Once a person becomes sensitized to isocyanates, extremely small amounts can trigger potentially life-threatening asthma attacks.
Is spray foam insulation safe to breathe during application?
Simply put—no. It is unsafe to breathe around spray foam during installation. The manufacturing process creates off-gassing fumes as a natural byproduct of the chemical reaction. These vapors and aerosols can migrate throughout a building if the area isn't properly isolated and ventilated.
Furthermore, cutting or trimming partially cured foam may generate dust containing unreacted isocyanates and other chemicals. These airborne contaminants can linger until properly ventilated and thoroughly cleaned.
Required protective equipment
For anyone involved in the application process, comprehensive personal protective equipment (PPE) is non-negotiable:
Respiratory protection – The most essential piece of gear. Options include:
NIOSH-approved full-face or half-mask air-purifying respirator with organic vapor sorbent and P100 particulate filter
For higher exposure scenarios, positive-pressure, air-supplying respirator
Skin protection – Chemical resistant gloves (nitrile, butyl rubber, neoprene or PVC), disposable coveralls or chemical-resistant clothing, and head protection
Eye protection – Safety goggles or full-face shield unless using a full-face respirator
All workers should be trained in proper PPE usage, including fit testing for respirators. Signs and barriers should also restrict access to the work area, allowing only properly protected personnel.
Ventilation requirements
Proper ventilation serves dual critical purposes: protecting workers and ensuring safe re-entry conditions. The Environmental Protection Agency (EPA) emphasizes that ventilation is required by OSHA as an engineering control to reduce worker exposures to acceptable levels.
Two ventilation approaches are essential:
Local exhaust ventilation directly at the application site to capture contaminants at their source
General ventilation of the entire area after application to prevent chemical migration
Critically, studies show that ventilation alone isn't sufficient—proper PPE must still be used during application. Ventilation must continue after installation until the material has fully cured, off-gassing has stopped, and vapors have been removed.
For homeowners, this means vacating the premises entirely during installation. The Canadian Professional Air Quality Association recommends residents and pets evacuate for at least 24 hours after application, although this may vary based on product type and building conditions.
Ultimately, the installation of spray foam insulation carries significant health risks that require professional handling with appropriate safety measures. Homeowners should never be present during installation and should carefully follow re-entry guidance from certified installers.
Post-Installation Safety Period
After installation, spray foam insulation continues to undergo chemical reactions that present potential health risks. The post-installation safety period requires careful attention to ensure occupants return only when conditions are safe.
How long to stay out of house after spray foam installation
The time needed away from home after spray foam installation varies based on product specifications and environmental factors. Generally, manufacturers and industry experts recommend evacuating the premises for at least 24 hours after application. However, this timeframe might extend to 72 hours depending on the specific product and installation conditions.
Several factors influence safe re-entry times:
The type of spray foam used (open vs. closed cell)
Amount of foam applied per volume of space
Temperature and humidity during application
Ventilation effectiveness
Presence of vulnerable individuals (children, elderly, those with respiratory conditions)
Despite common industry guidance suggesting 24 hours, it's essential to consult your specific product manufacturer for definitive guidance. Indeed, some manufacturers estimate one-component foam might take approximately 8 to 24 hours to cure.
Curing process and chemical off-gassing
Spray foam insulation undergoes a complex curing process immediately after application. Initially, the foam becomes tack-free within 20-30 seconds. Soon after, it develops its waterproofing skin and becomes walkable within 1-2 minutes. Nevertheless, this initial hardening does not indicate complete curing.
Throughout curing, spray foam releases volatile organic compounds (VOCs) through a process called off-gassing. This occurs as part of the chemical reaction that transforms liquid components into solid insulation. The Environmental Protection Agency (EPA) explains that curing time varies based on:
Product formulation
Applicator technique
Foam thickness
Temperature and humidity
For spray foam installed correctly and within manufacturer guidelines, off-gassing typically stops after the 24-hour curing period. Conversely, foam installed incorrectly or "off-ratio" could potentially off-gas indefinitely.
Signs that it's safe to return home
Determining when it's truly safe to re-enter requires careful assessment. Primarily, follow the manufacturer's recommended re-occupancy time—typically 24 hours with proper ventilation. Additionally, these signs indicate safe re-entry:
Complete absence of chemical odors
No respiratory symptoms or irritation upon brief entry
Proper ventilation has been maintained throughout the curing period
Air quality testing shows acceptable VOC levels
Should occupants experience concerning symptoms after returning home—primarily respiratory problems, eye irritation, or persistent unusual odors—they should immediately leave the premises and seek medical attention. Furthermore, contacting the contractor or an independent air quality expert may be necessary to diagnose potential problems.
Remember that spray foam safety depends heavily on proper installation. For optimal safety, ensure your contractor is properly certified and follows all manufacturer guidelines regarding installation and recommended re-entry times.
Long-Term Health Considerations
Many homeowners wonder about the long-term safety of spray foam insulation once it has fully cured. Unlike the immediate installation risks, long-term health considerations remain an area where scientific research continues to evolve.
Is spray foam insulation safe after it cures?
Once properly cured, spray foam insulation is typically considered relatively inert. However, this safety depends heavily on correct installation. Properly mixed and applied foam generally completes its chemical reaction within 24-72 hours, after which most manufacturers consider it safe. Yet, important safety distinctions exist between proper and improper installations.
Spray foam that continues off-gassing beyond the normal curing period often indicates an improper installation—specifically, when the components weren't mixed in the correct 1:1 ratio. In these cases, unreacted chemicals may continue releasing harmful compounds indefinitely.
Potential ongoing emissions
Even correctly installed spray foam may emit certain chemicals over time. Research has identified several concerning emissions:
Flame retardants like TCPP (tris(1-chloro-2-propyl) phosphate), which has been classified by the EPA as having a high hazard for reproductive and developmental effects
VOCs (volatile organic compounds) that can cause headaches and nausea during acute exposure and possibly link to cancer with prolonged exposure
Formaldehyde, a known carcinogen that irritates the eyes, nose, and throat
Temperature significantly affects these emissions—one study found TCPP concentrations were 3.4 times higher at elevated temperatures compared to typical basement temperatures. This suggests emissions may increase during warmer seasons or when heating systems operate.
Research on long-term exposure effects
Research on long-term health impacts presents concerning findings. Workers regularly exposed to spray foam components have developed chronic conditions including asthma and other respiratory issues. Additionally, a particularly troubling condition called "sensitization" can occur—after enough exposure, affected individuals become more sensitive to other air contaminants like dust or pollen, experiencing respiratory issues more easily.
Primarily, the Environmental Protection Agency (EPA) acknowledges that "the potential for off-gassing of volatile chemicals from spray polyurethane foam is not fully understood and is an area where more research is needed". Essentially, this underscores the scientific uncertainty surrounding these materials' long-term safety.
For homeowners with existing spray foam, adequate ventilation remains crucial for minimizing potential risks. Additionally, avoiding activities that might disturb the foam—such as heating, cutting, or grinding—can prevent the release of toxic emissions, as cured polyurethane can release isocyanates when heated or burned.
Special Safety Considerations for Vulnerable Groups
Certain populations face heightened risks from spray foam insulation exposure. Understanding these specific vulnerabilities can help families make informed safety decisions.
Is spray foam insulation safe for pets?
Pets face unique dangers from spray foam insulation. During installation, animals must be completely removed from the premises as they cannot wear protective equipment and are particularly vulnerable to chemical fumes. After application, vapors may linger until properly ventilated and thoroughly cleaned.
Household pets should never have access to uncured spray foam. If ingested, spray foam products can expand in the stomach, potentially forming large masses requiring surgical removal. Additionally, cured particles can cause severe gastrointestinal and respiratory irritation in animals.
Following installation, pets should remain away from treated areas for at least 24-48 hours, depending on manufacturer recommendations. Even after curing, it's best to prevent pets from directly contacting or chewing on insulated areas.
Considerations for children and elderly
Children and elderly individuals typically have more sensitive respiratory systems and developing or compromised immune responses. Throughout the installation process, these vulnerable groups must be temporarily relocated to a safe location.
The Environmental Protection Agency (EPA) explicitly warns that spray polyurethane foam products are inappropriate for "creative" uses such as science or art projects and should not be used around children.
Prior to returning home, parents should ensure the space has been thoroughly ventilated and all installation debris properly removed. Older individuals with existing health conditions should exercise particular caution regarding re-entry timeframes.
People with respiratory conditions or chemical sensitivities
Individuals with respiratory issues or chemical sensitivities face the most serious risks. The EPA emphasizes that people with "a history of skin conditions, respiratory allergies, asthma, or prior isocyanate sensitization should carefully review product information when considering SPF products and may want to consider alternatives".
For sensitized individuals, there is no recognized safe level of exposure to isocyanates. Even after curing, some spray foams retain residual odors that can trigger reactions in sensitive people. Isocyanates have been identified as "a leading attributable chemical cause of asthma in the workplace".
Primarily, those with existing health vulnerabilities should consider non-spray insulation alternatives like blown cellulose, fiberglass, or mineral wool that introduce fewer chemicals into the living environment.
Conclusion
Final Safety Considerations
Spray foam insulation presents significant advantages for energy efficiency, though safety remains paramount throughout its lifecycle. Professional installation by certified contractors stands essential, as improper application can lead to persistent off-gassing and potential health risks.
Homeowners must carefully weigh the benefits against safety considerations, particularly regarding vulnerable household members. Though properly cured spray foam generally proves safe, certain groups face heightened risks that warrant extra precaution or alternative insulation choices.
Safety protocols demand strict adherence during installation, including mandatory evacuation periods and proper ventilation. Certified installers must follow manufacturer guidelines precisely, ensuring optimal curing conditions and minimizing potential health hazards.
Research continues regarding long-term health effects, especially concerning chemical emissions and sensitization risks. Homeowners should maintain proper ventilation systems and avoid disturbing installed foam through cutting or heating, which could release harmful compounds.
The decision to use spray foam insulation requires thorough consideration of all safety aspects, from initial installation through long-term occupancy. Consulting qualified professionals helps ensure appropriate safety measures protect everyone in the household.
