If you own a home built before 1980, there's a good chance it contains asbestos cement board — a durable building material that was once considered a construction marvel. Also known by the brand name Transite, this material was widely used throughout the 20th century for its fire resistance, strength, and affordability. Today, millions of American homes still contain these materials, and understanding what you're dealing with is the first step toward keeping your family safe.
What Is Asbestos Cement Board?
Asbestos cement board is a composite material made by mixing asite fibers with Portland cement. The asbestos fibers — typically chrysotile (white asbestos) — gave the material remarkable durability and heat resistance. Transite was a popular brand name that became almost synonymous with asbestos cement products, much like how "Kleenex" became shorthand for tissues.
Manufacturers produced asbestos cement board from the early 1900s through the late 1970s, when regulations began restricting asbestos use. The material was prized because it wouldn't burn, resisted rot and pests, and could last for decades with minimal maintenance.
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Asbestos cement products were used in many areas of residential construction. Here are the most common places to look:
- Exterior siding: Asbestos cement shingles and flat panels were extremely popular for home siding. They often have a wood-grain texture or appear as overlapping shingles.
- Roofing shingles: Flat or corrugated asbestos cement roofing was common on homes, garages, and sheds.
- Soffit and fascia boards: The areas under roof overhangs often contain asbestos cement panels.
- Ductwork and flue pipes: Transite was frequently used for HVAC ducts, furnace flues, and chimney pipes due to its heat resistance.
- Water and sewer pipes: Some older homes have Transite pipes for water supply or drainage lines.
- Foundation walls and crawl spaces: Asbestos cement panels sometimes lined basement walls or served as vapor barriers.
When Does Asbestos Cement Board Become Dangerous?
Asbestos cement board that remains intact and undisturbed generally poses minimal risk. The asbestos fibers are locked within the cement matrix, which prevents them from becoming airborne. According to the EPA, asbestos-containing materials in good condition are often best left alone.
The danger arises when the material is disturbed. Activities that can release asbestos fibers include:
- Cutting, drilling, or sawing through asbestos cement board
- Sanding or scraping the surface
- Breaking or crumbling damaged sections
- Pressure washing asbestos cement siding
- Demolition work without proper precautions
- Natural weathering that causes the material to become friable (crumbly)
When asbestos fibers become airborne, they can be inhaled and may cause serious health problems over time. This is why identifying whether your home contains asbestos cement board matters — especially before any renovation or repair project.
How to Identify Asbestos Cement Board
You cannot identify asbestos just by looking at a material. However, certain visual clues can suggest the presence of asbestos cement board:
- Age: If your home was built before 1980, suspect materials should be tested.
- Appearance: Asbestos cement siding often looks like thick, rigid shingles in gray, white, or muted colors. It may have a slightly grainy texture.
- Weight: Asbestos cement is notably heavier than modern fiber cement or vinyl siding.
- Sound: Tapping asbestos cement produces a solid, almost stone-like sound rather than a hollow plastic tone.
The only way to confirm whether a material contains asbestos is through laboratory testing. A sample of the material is analyzed under specialized microscopy to detect and identify asbestos fibers.
What to Do If You Suspect Asbestos Cement Board
If you think your home has asbestos cement board, follow these guidelines:
- Don't disturb it. Leave the material alone until you know what you're dealing with.
- Get it tested. Before any renovation, repair, or demolition, test suspect materials.
- Hire professionals for removal. If testing confirms asbestos and the material needs to be removed, work with licensed asbestos abatement contractors.
- Consider encapsulation. In some cases, intact asbestos cement siding can be safely covered with new siding rather than removed.
Frequently Asked Questions
Can I remove asbestos cement siding myself?
Many states allow homeowners to remove small amounts of asbestos-containing materials from their own single-family homes, but regulations vary widely. Even where it's legal, DIY removal is risky without proper safety equipment and disposal procedures. Most experts recommend hiring a licensed abatement professional, especially for larger projects.
Is it safe to live in a house with asbestos cement siding?
Yes, in most cases. When asbestos cement board is intact and undisturbed, the fibers remain bound within the cement and don't pose a health risk. The concern arises when the material is damaged, deteriorating, or disturbed through cutting, drilling, or demolition. Regular inspection for damage is a sensible precaution.
How much does it cost to test for asbestos in my home?
Professional asbestos inspections typically cost between $200 and $800 depending on your location and the number of samples taken. DIY test kits offer a more affordable option — you collect the sample yourself and mail it to an accredited laboratory for analysis, receiving certified results at a fraction of the cost.
Know What's in Your Home
If you're planning a renovation, dealing with damaged siding, or simply want peace of mind about an older home, testing is the smart first step. The MycoTest DIY Asbestos Test lets you collect a small material sample yourself and send it to a certified laboratory for analysis — no inspector appointment needed, with clear results delivered in days.
Disclaimer: This article is for informational purposes only and does not constitute medical, legal, or professional advice. MycoTest DIY kits are screening tools. For confirmed contamination, consult a certified environmental professional.
