Should You Remove Cement-Asbestos Siding?

Cement-Asbestos Siding Tiles
Cement-Asbestos Siding Tiles. GeoStock / Getty Images

If you have cement-asbestos siding, take a moment to consider before you begin ripping it off.  Because it contains asbestos, it is potentially dangerous if disturbed.

Yet asbestos, if left alone, is not dangerous. It is when you start sanding, sawing, ripping, or otherwise demolishing an asbestos product that you start to run into problems.

Bottom Line

Cement-asbestos siding tiles do not need to be removed simply because they contain asbestos.
Cutting, sanding, or breaking these tiles, though, is a health hazard.  These actions release asbestos fibers into the air, and breathing these fibers is dangerous.
This type of siding is usually found on houses built between 1905 and the 1960s.  Many of these houses still exist.
These tiles have the benefit of being fireproof.  Only the tiles are fireproof, not the underlying structure.
Removal can be done either by the homeowner or by an abatement company.
Cement-asbestos siding should not be confused with a product that sounds similar, fiber-cement siding.  Fiber-cement siding contains no asbestos, making it safe to remove.

Why Remove It?

Consider this carefully. If it's your intention to reside your house, first speak to the siding company. Most siding companies are well-experienced at siding over existing siding.

Removing the asbestos cement siding, in addition to the health hazards, only adds more work to your project and will cost that much more.  Removal of existing siding is not part of most siding companies' estimates.  Even if they do agree to do this, it will be an added cost and the company will most likely contract out the job to a demolition company.

Keep in mind that removing asbestos cement siding is not a simple matter of calling up a local contractor. Depending on your locality, chances are good that you'll need to obtain special permits and have a special asbestos abatement company perform the work.

Why It's On Your House In The First Place

Asbestos-cement is a mixture of portland cement reinforced with asbestos fibers.

The portland cement binds asbestos fibers into a hard mass.

Asbestos cement was first developed in 1905 by the Johns-Manville company, who became one of the premier manufacturers of cement-asbestos materials.

It was used in places where fire or extreme heat needed to be contained: chimneys, dormer windows, skylights, scuppers, shingles, and nail holes on roofs, and for protecting beams, posts, walls, and ceilings.

It was natural that the next step would be to find a way to manufacture this into siding shingles for residences.

Good Points

  • Highly fire resistant.  In fact, asbestos is one material that completely resists fire because it is a mineral.
  • Resists termite damage and rot.
  • Easy to clean (though beware of using pressure washers, as this may crack the product).
  • Easy to paint because it does not soak up paint as quickly as more porous siding, such as wood clapboard.
  • One-for-one replacement:  because cement siding comes in tiles, much like ceramic floor tiles, they can be replaced individually if one should break.  Contrast this with fiber-cement lap siding or vinyl siding which would require replacement of an entire siding plank.

Bad Points

  • Very brittle.  In fact, you can crack it just by hitting it with a lawnmower.
  • Dangerous if pulverized by sawing, sanding, breaking, etc.
  • Difficult to find replacements.
  • Cannot be refurbished. For example, wood clapboard can be sanded and repainted, or cedar shake siding can be sandblasted and re-stained. Can't do this with asbestos cement siding.
  • Lowers resale value as many buyers consider it unattractive.  You will be hard pressed to find anyone who has a soft spot in his or her heart for asbestos cement siding.