The topic of roofing felt toxicity often centers on asphalt-based felts used in many residential and commercial roofs. While modern roofing felts are designed to be safe for installers and occupants, there are important considerations around potential toxins, fumes during application, and the historical use of asbestos in some older products. This guide explains what roofing felt is, what substances may be involved, potential health risks, and how to choose safer, compliant options for current projects in the United States.
What Is Roofing Felt
Roofing felt, also called underlayment, is a protective layer installed between the roof deck and shingles or other roofing materials. The most common type in the United States is asphalt roofing felt, made from a mat of fiberglass or organic fibers coated with asphalt and mineral granules or a laminated layer. This material provides weather resistance, acts as a secondary moisture barrier, and helps extend roof life. Some cold-applied or self-adhesive felts use bitumen with synthetic binders. Understanding the composition helps identify potential toxic components and safer installation practices.
Possible Toxic Substances Involved
In modern asphalt roofing felts, the primary chemical exposure concerns relate to asphalt and solvents used in production or installed during hot applications. Volatile organic compounds (VOCs) can be emitted when heated during installation, and some felts may release small amounts of polycyclic aromatic hydrocarbons (PAHs) as the asphalt cures. Older, pre-1980s felts sometimes contained asbestos or asbestos-containing materials as part of the felt’s reinforcement. Any suspicion of asbestos requires professional testing and abatement. Always review the product data sheet (PDS) and Material Safety Data Sheet (MSDS) for specifics on a particular brand and lot.
Health Risks At A Glance
For most homeowners and contractors, exposure risks are tied to installation and handling rather than long-term contact once a roof is sealed. During installation, hot asphalt felts can emit fumes that may irritate the eyes, nose, and throat, and in poorly ventilated spaces can cause dizziness or headaches. Prolonged, high-level exposure to solvents and VOCs may have more serious health implications, though modern products are designed to minimize emissions. For aging or damaged felts, skin contact with wet asphalt can cause dermatitis in sensitive individuals. If asbestos is present, inhaling fibers poses a significant long-term risk and requires professional intervention.
During Installation Versus After Installation
After installation, roofing felt generally poses minimal risk. Once the underlayment is covered and sealed, fumes dissipate, and the material remains inert under normal conditions. Ventilation during installation is crucial to minimize exposure to fumes. Keep workers informed about weather conditions; high temperatures can increase solvent volatility. If residents will be present, consider scheduling work during cooler parts of the day or using quick-setting materials to reduce exposure time. For those with respiratory sensitivities, using lighter-weight or synthetic underlayment options can help reduce irritant exposure.
Older Felts And Asbestos
Asbestos was historically used in some building products and roofing felts due to its durability and heat resistance. Asbestos-containing felts are a concern when dealing with very old roofs or repair materials. If suspect, do not disturb the material; contact a licensed asbestos professional to perform preliminary testing and, if needed, safe removal. Modern roofing felts in the United States are largely asbestos-free, but mislabeling or legacy materials can occur in some installations. When purchasing or inspecting materials, ask for clear documentation confirming the absence of asbestos and verify compatibility with local regulations.
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Environmental Impact And Disposal
Disposal of used roofing felt should follow local regulations for construction debris and hazardous waste, especially if the material contains asbestos or solvents. Recycling options are limited for asphalt-containing felts, but some facilities accept clean, dry felt for grinding into asphalt extensions or for energy recovery where permitted. Burning felts is generally discouraged due to toxic smoke and environmental harm. Proper disposal helps prevent soil and water contamination and reduces air pollution from exposed solvents and PAHs.
How To Handle Safely
Safe handling practices reduce health risks during installation and removal. Always wear proper personal protective equipment (PPE), including gloves, eye protection, and a respirator or well-fitted mask in dusty or hot conditions. Ensure adequate ventilation when applying hot asphalt felts and avoid work in enclosed spaces. Keep heat sources away from vulnerable materials and follow manufacturer guidelines for temperature limits. If an asbestos concern is suspected, cease work and contact a licensed environmental professional for testing and abatement guidance. Store unused materials in sealed containers and keep them away from children and pets.
Choosing Safer Roofing Felt Options
For projects aiming to minimize toxicity and emissions, consider the following safer choices. Look for felts with low VOC emissions and products that specify a low-odor formulation. Opt for non-asbestos underlayment and verify product certifications such as ASTM standards and manufacturer compliance. Evaluate alternative underlayments like synthetic or non-bitumen membranes when appropriate for weather conditions, climate, and roof design. Always request up-to-date MSDS or PDS from suppliers and consult local building codes to ensure chosen materials meet fire resistance and moisture protection requirements. Regular inspections after installation help confirm that the underlayment remains intact and effective over time.