If your home was built before 1980 and still has its original siding, there’s a real chance it’s asbestos. You usually can’t confirm it by looking, and the wrong move, like pressure washing or scraping it, is exactly what turns a stable material into a health risk.
Here’s the short answer on how to identify asbestos siding: look for hard, brittle, cement-like shingles roughly 12 inches by 24 inches, often with a wavy or grooved bottom edge and two or three nail holes along the base. If that describes your siding on a home of that age, treat it as asbestos until a lab test proves otherwise.
What Asbestos Siding Actually Is
Asbestos siding is exterior cladding made from asbestos-cement, a mix of Portland cement and asbestos fibers added for strength and fire resistance. Common from the 1920s through the 1970s because it was cheap, rigid, and nearly fireproof, it still sits on older homes across Delaware, Chester, Montgomery, and Bucks counties in Pennsylvania, and Camden, Burlington, and Gloucester counties in New Jersey. It was phased out as the health risks became clear.
You’ll see it described three ways, and the differences matter:
- Asbestos shingles siding: the most common form. Small rectangular pieces, around 12 inches by 24 inches, in overlapping rows, often with a wavy, scalloped, or grooved bottom edge. It is sometimes called transite siding, after a common asbestos-cement brand.
- Asbestos siding panels: larger flat sheets that cover more area with fewer seams, common on additions, gables, and some commercial buildings.
- Asbestos siding: the umbrella term for any exterior asbestos-cement cladding, shingle or panel.
What Does Asbestos Siding Look Like?
No single sign is proof, but several of these together point to asbestos:
- Age. Asbestos-cement siding went up mostly between the 1940s and the 1970s. Original siding from that era is the first thing to question.
- Size and shape. Most shingles measure about 12 inches by 24 inches and sit in tidy, uniform rows.
- Bottom edge. Look for a wavy, scalloped, or vertically grooved edge. Straight-cut edges exist too, so this is a clue, not a rule.
- Nail pattern. Each shingle is usually face-nailed with two or three visible nail holes along the bottom.
- Feel. The material is hard, dense, and brittle. It doesn’t flex like vinyl or show wood grain, and it cracks rather than dents.
Here’s the part most guides skip: you cannot confirm asbestos by sight alone. Vinyl, wood, and fiber cement can all mimic the look. The only reliable way to know is a lab test of a small sample, collected by a licensed professional so no fibers are released.
When to Stop Guessing and Call a Professional
If any of these are true, stop investigating on your own and get the siding tested before you touch it.
- The material is cracked, broken, crumbling, or shedding a chalky powder
- Shingles are loose, missing, or shifted out of line
- You’re planning a project that would cut, drill, sand, scrape, or pressure wash the siding
- You’re not sure what it is and the home predates 1980
That third point catches homeowners off guard. A routine repaint or pressure wash can disturb asbestos siding and release fibers into the air around your home.
Why Damaged Asbestos Siding Spreads Hidden Problems
Intact, painted asbestos siding that no one disturbs is generally low risk. The problem starts when it breaks down, and on a home 50 or more years old, it usually has. Cracked shingles release microscopic fibers, and those airborne fibers are the real hazard, not the siding sitting quietly on your wall.
The bigger problem is the one you can’t see. Once shingles crack, shift, or fall away, water gets in behind the cladding. In southeastern Pennsylvania and South Jersey, freeze-thaw cycles widen those cracks every winter and push moisture into the sheathing and framing. By the time a homeowner notices, the repair is no longer just siding. It’s rot, and sometimes structural damage, under a material no one wanted to touch.
What to Do If You Have Asbestos Siding
You have three honest paths, and the right one depends on the condition of the siding and your plans for the home.
- Leave it and monitor. If the siding is intact, painted, and undisturbed, it can often stay safely. Check it once a year for damage.
- Encapsulate it. Sealing and painting intact siding locks fibers in place and buys time at a lower cost.
- Remove and replace it. When the siding is deteriorating, or when you’re ready to re-side, removal by a licensed asbestos abatement contractor is the permanent fix.
Whatever you choose, a few rules never change. Don’t sand it, break it, or blast it with a pressure washer, and never remove it yourself. Removal and disposal are regulated, and the EPA is clear that this is work for trained professionals.
Cost depends on home size, wall prep, framing repairs, and disposal, so figures vary by project. For current estimates, see our siding cost guide, then reach out for a written evaluation of your home.
See It Before You Commit
Thinking past removal to a new exterior? Use our free 3D Design Preview tool to see fiber cement colors and profiles on a model of your own home.
The Modern Replacement for Asbestos Siding
If replacement is on the table, there’s a fitting piece of history here. Modern fiber cement siding is the direct descendant of asbestos-cement: the same cement-based durability and fire resistance, but the asbestos is gone, replaced by cellulose fibers that carry none of the health risk.
James Hardie is the most common fiber cement brand in our market, with products like HardiePlank® lap siding and HardiePanel® vertical siding. As a James Hardie Elite Contractor, Porter Family Exteriors installs to manufacturer specifications, so your new siding is done right the first time. We are the only company in the Northeast to win both the James Hardie President’s Club and the James Hardie Service Excellence Award, two years running. Every fiber cement installation is backed by James Hardie’s 30-year non-prorated product warranty. For homeowners replacing old asbestos shingles, it’s the closest thing to a like-for-like upgrade, without the material that caused the problem. See the siding options we install, or download our James Hardie siding guide, when you’re ready to plan a replacement.
Frequently Asked Questions About Asbestos Siding
Is asbestos siding dangerous if I leave it alone? Intact, undisturbed, painted asbestos siding is generally low risk. The danger comes from fibers released when it’s cut, broken, sanded, or pressure washed. Leave intact siding alone and have it tested before any work.
Can I tell if my siding is asbestos without testing? You can spot strong clues, like age, shingles around 12 inches by 24 inches, a wavy bottom edge, and a hard cement feel, but you cannot confirm it by sight. Only a lab test of a professionally collected sample is definitive.
Can I remove asbestos siding myself? No. Removal and disposal are regulated, and doing it yourself releases fibers and can create disposal violations. Always use a licensed asbestos abatement contractor.
Schedule an Exterior Evaluation
If you suspect asbestos siding on your home, the smartest first step is a professional look before anyone disturbs it. Our team has been helping homeowners across southeastern Pennsylvania and South Jersey make safe, informed siding decisions since 1976. Read about our asbestos siding removal process, or reach out to Porter Family Exteriors today for a free, written evaluation.
