Picturing something fried is one way to understand terms related to asbestos in roofing and siding. Fried foods or burnt materials are dry, crumbly or crispy and rough around the edges. They are usually easy to break up or apart. Something "nonfriable" is not easy to break down because its fibers are strong and tightly held together. A nonfriable material can become "friable" with wear and tear, though, and can come apart with applied pressure [sources: Merriam-Webster, MDH].
Most cement or asphalt composites used in roofing and siding are generally considered nonfriable, but those with a large paper make up are friable because they come apart with pressure. Both types release breathable particles of asbestos when cut into or removed by tearing and pose a health hazard [source: MDH].
Checking materials for asbestos is sometimes just a matter of looking for markings or product numbers and researching. With care and help from trained professionals, siding and roofing with asbestos products can be removed or covered, but they typically pose a low risk if intact and left alone [source: Woods].