More than a hundred years ago manufacturers were drawn to the fire- and chemical-resistant properties as well as the flexibility and strength of the silicate rock asbestos. In the postwar U.S. building boom, hundreds of thousands of houses were sided or re-sided using asbestos cement siding — asbestos mixed with Portland cement — in board or shingle form. Then, in the 1960s and ’70s, as scientists and the public became aware of the relationship between asbestos and various forms of cancer, use of asbestos in building materials was restricted and finally banned.

Experts say that, left intact, the old asbestos siding presents no danger. What can be dangerous is its removal. Breaking or otherwise damaging the siding — sawing, drilling, or dropping it — can release asbestos fibers into the air.

Most states and some cities have rules about removal. In many areas, homeowners are free to do the removal themselves if they follow certain precautions. But when it comes to asbestos removal by professionals, it’s another story. In many states a contractor re-siding a house that has asbestos siding must be certified in asbestos abatement or bring in a certified abatement contractor.

Cover It Up

Siding contractors are experienced at siding over the old asbestos. “Most times we leave it intact,” says Chris Zorzy, owner of A&A Services, in Salem, Mass. “You have to put an insulation panel over the asbestos, then run the vinyl over that. It encapsulates it and keeps it stationary.”

Since, in many cases, the asbestos siding went on over the home’s original wood siding, the bigger challenge is installing trim that makes the house look appealing while wearing three layers of siding. “I tell my customers that what makes a siding job pop is how well the trim is done, that it looks natural and has a nice reveal,” Zorzy says.

But if siding over isn’t practical, or the homeowner insists that the asbestos siding be removed, it’s important to know whether or not your state requires a certified asbestos contractor to do the removal. In Maine, for example, regulations allow a homeowner in a single-family home to remove their own siding, but you must hire a licensed asbestos abatement contractor if you want anyone else to remove your asbestos siding for you. Ditto Georgia. In Atlanta, Exovations refers customers for fiber cement re-siding to an abatement contractor. When he is finished, the company returns to install, owner Roone Unger says.

New Jersey, on the other hand, does not require a licensed asbestos abatement contractor to remove existing asbestos siding. But whoever does remove it must bag and send the material to a special landfill. New Jersey lists nine landfills approved to accept asbestos waste.