Shingles with Asbestos
Shingles with asbestos—commonly marketed throughout the twentieth century under trade names such as Transite, Johns-Manville, Keasbey & Mattison, and Flintkote—were among the most popular exterior cladding and roofing products installed between the 1920s and late 1970s. Valued by builders for their exceptional fire resistance, rot immunity, and structural rigidity, these cement-composite shingles remain common on millions of older residential and commercial properties today.
Identification, Visual Characteristics, and Historical Manufacturers
Identifying shingles with asbestos begins with recognizing their distinct physical properties and aesthetic hallmarks. Unlike modern vinyl or lightweight aluminum siding, asbestos-cement shingles possess a rigid, ceramic-like density, typically measuring approximately 12 by 24 inches or 9 by 18 inches with a thickness of roughly 1/8 to 3/16 inch. When tapped lightly with a metal tool, they produce a distinctive brittle clinking sound similar to slate or earthenware rather than the hollow resonance of plastic or wood.
Manufacturers produced these exterior shingles in numerous decorative patterns designed to mimic natural cedar shakes or stone tiles. Common aesthetic profiles include wavy, scalloped, or straight-cut bottom edges, often embossed with deep vertical woodgrain striations. Major industrial corporations—including Johns-Manville (under the trade name Transite), Keasbey & Mattison, Flintkote, Celotex, and GAF Ruberoid—manufactured millions of tons of these composite products, formulating them with 15% to 30% chrysotile mineral fibers bound in dense Portland cement.
| Manufacturer / Brand Name | Primary Product Format | Typical Asbestos Concentration | Distinguishing Aesthetic Features | Peak Manufacturing Era |
|---|---|---|---|---|
| Johns-Manville (Transite) | Exterior wall siding & roofing shingles | 15% to 25% Chrysotile | Embossed woodgrain striations, wavy bottoms | 1925 to 1978 |
| Keasbey & Mattison (Century) | Fireproof roofing slate & siding tiles | 20% to 30% Chrysotile / Amosite | Smooth chamfered edges, slate-gray coloration | 1930 to 1968 |
| Flintkote Building Materials | Weather-tight siding shingles | 15% to 20% Chrysotile | Straight butt edges with staggered vertical texture | 1940 to 1976 |
| Celotex Corporation | Insulated exterior siding panels | 10% to 25% Chrysotile | Thick composite backing with mineral-cement face | 1935 to 1975 |
| GAF Ruberoid Division | Mineral-surfaced roofing shingles | 15% to 25% Chrysotile | Granule-coated surface mimicking asphalt shingle | 1945 to 1979 |
Management Strategies: Overlay Encapsulation vs Professional Abatement
When discovering shingles with asbestos on a property, homeowners must evaluate management options based on physical condition. Intact asbestos-cement shingles are classified under federal EPA NESHAP regulations as Category II non-friable materials. This means that as long as the shingles remain unbroken, sound, and securely fastened to structural sheathing, they do not release respirable fibers. Immediate removal is rarely mandated by building codes unless the materials are crumbling, broken, or slated for complete demolition.
One of the most cost-effective and legally accepted management techniques is siding overlay encapsulation. Instead of stripping the existing shingles, siding contractors install foam backer board insulation directly over the asbestos-cement cladding, subsequently securing modern vinyl, aluminum, or composite fiber siding on top. This approach completely encapsulates the hazardous material, enhances residential thermal energy efficiency, and eliminates the substantial expense and disposal logistics of full abatement, provided installers pre-drill carefully or use pneumatic fastening systems that avoid shattering the shingles.
| Evaluation Parameter | Siding Overlay / Encapsulation | Complete Professional Shingle Removal |
|---|---|---|
| Typical Project Cost | $5 to $10 per square foot installed | $8 to $16 per square foot removal only |
| Hazardous Waste Disposal Fees | $0 (Materials remain on structure) | High ($1,500 to $4,000+ landfill tipping fees) |
| Occupant & Environmental Risk | Extremely low; zero fiber disturbance | Moderate during active unfastening and handling |
| Regulatory Permitting Burden | Standard residential building permit | Mandatory 10-day state environmental notice |
| Permanent Hazard Resolution | Encapsulated; requires future disclosure | Permanent 100% elimination of hazardous minerals |
When shingles are severely damaged by freeze-thaw cycles, cracked by tree impacts, or must be removed for major structural additions, removal must be executed with non-destructive wet techniques. Workers must continuously mist the siding with surfactant-treated water, gently unfasten individual nails using specialized shingle pullers, and avoid power-sawing, sanding, breaking, or dropping the shingles from ladders into dumpsters.
Disposal of exterior shingles is strictly regulated. Property owners and contractors cannot place asbestos shingles into municipal curbside trash or standard construction debris roll-off dumpsters. The shingles must be packaged in lined dumpsters or heavy 6-mil poly bags, accompanied by an EPA waste shipment manifest, and transported to a licensed solid waste landfill permitted to receive non-friable Category II asbestos materials.
How to Safely Handle and Manage Shingles with Asbestos
Step-by-step roadmap for homeowners inspecting, maintaining, or replacing exterior asbestos-cement shingles.
Perform a Visual Inspection for Structural Damage
Examine exterior walls to determine if shingles are intact and flat, or if they exhibit extensive cracking, chipping, and weathering.
Confirm Mineral Composition with an Accredited Lab
Collect a small broken corner piece under wet conditions and submit it for certified Polarized Light Microscopy analysis.
Evaluate Siding Overlay Encapsulation Options
Consult professional siding contractors about installing foam insulation backer boards and modern vinyl siding directly over the shingles.
Execute Professional Removal Using Wet Non-Destructive Methods
If removal is necessary, hire licensed abatement contractors who utilize wet unfastening techniques and certified hazardous disposal.
Frequently Asked Questions (8 Questions Answered)
Q1: How can I tell if my exterior shingles have asbestos?
Asbestos shingles are rigid, brittle cement-like tiles measuring 12x24 inches with wavy or straight edges, installed prior to 1980.
Q2: Are shingles with asbestos dangerous if left alone?
No, intact non-friable shingles pose no health risk as long as they are not sawed, broken, power-washed, or sanded.
Q3: Can I install new vinyl siding over asbestos shingles?
Yes, installing foam insulation backer board and vinyl siding directly over intact shingles is an approved, common encapsulation method.
Q4: Can I pressure wash shingles with asbestos?
No, power-washing erodes the cement matrix, dislodging millions of carcinogenic fibers into the air and surrounding soil.
Q5: How much does it cost to remove asbestos siding shingles?
Professional removal typically costs $8 to $16 per square foot, totaling $8,000 to $18,000 for an entire residential home.
Q6: Can homeowners legally remove asbestos shingles themselves?
In some states homeowners may remove non-friable exterior shingles, but many states mandate licensed abatement contractors.
Q7: Where can asbestos siding shingles be disposed of?
Shingles must be delivered to a licensed municipal or private landfill specifically permitted to accept non-friable asbestos waste.
Q8: What were asbestos shingles made of?
Asbestos shingles consist of approximately 15% to 30% chrysotile mineral fibers compressed tightly into a Portland cement binder.
Final Thoughts & Key Takeaways
Encountering shingles with asbestos on residential or commercial buildings should not cause panic. Because the hazardous mineral fibers are locked securely within a dense Portland cement matrix, intact shingles pose virtually zero health risks to building occupants. By implementing protective vinyl siding overlays or contracting certified abatement teams for non-destructive wet removal, property owners ensure long-term architectural beauty and environmental compliance.