Although the use of asbestos has declined since the 1980s, it remains in several different types of building construction materials for insulation and as a fire retardant. Typically, asbestos can be found in materials such as ceiling and floor tiles, heat-resistant fabrics and coatings, and roof shingles. You may also find asbestos in textured paint and patching compounds.

Unlike some home problems, such as water damage or pest infestations, asbestos can be very difficult to spot. Asbestos is a mineral in the form of microscopic fibers and was previously used in building materials for its bonding and fireproofing abilities. Insulation, roof shingles, ceiling tiles, floor tiles, pipe wrappings, soundproofing materials, and textured paint features like popcorn ceilings are common sources of asbestos, particularly in homes built before 1980.

Age is perhaps the biggest indicator of asbestos, as legislation passed in the 1970s labeled asbestos as dangerous and regulated its use in building materials. Signs of age in the form of wear and tear or material degradation are also indicators that asbestos fibers may be leaking into the air, but ultimately, it’s difficult to detect with the naked eye. If you have reason to suspect asbestos in your home, it’s best to hire a certified asbestos inspector.

Federal law doesn’t require homeowners to disclose the presence of asbestos in their home, but some states and local municipalities may require it. That is why it’s important to test an older home for asbestos and other health hazards before moving forward with a sale.

Knob and tube wiring is an older type of electrical wiring that's no longer used and generally not considered safe. However, some homes still have it, or may have a knob and tube wiring system that was incorrectly modified or rigged to work with a modern electrical system. Knob and tube wiring may contain asbestos insulation, but the only way to know is to have the material professionally tested.