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.

Unfortunately, asbestos is not easily identified and can often be hidden in plain sight in your home. While it can look like fluffy fibers, tiny pieces can also appear in materials like plastic or cement, making it impossible to identify on your own properly.

Plus, since asbestos is so dangerous when disturbed, you should never root around to try and find it. This job is best for a professional who can test for the material properly.

If you hire a dedicated asbestos inspector near you in addition to your local home inspector, it will cost between $200 and $800. If, however, your general home inspector happens to be certified as an asbestos inspector, they can charge you a smaller fee and tack on the cost to the home inspection. In general, home inspectors do not do physical testing, but will provide a visual assessment so you know what you are working with.

If you know your popcorn ceiling has asbestos, you should not attempt to clean it. It simply is not possible to learn how to clean asbestos safely without potentially releasing microscopic fibers into the air that could lead to severe illness in the future. Avoid disturbing or cleaning the ceiling until the asbestos removal company can get rid of the popcorn ceiling.