Asbestos Siding vs. Fiber Cement Siding: How to Tell the Difference

If you’re preparing to replace your home’s fiber cement siding, you’re likely eager to dig into the project. However, if you have an older home, you should pause to determine whether your siding contains asbestos. 

American homes built in the 1980s and earlier could have asbestos-based siding. Ripping it loose would expose you to dangerous airborne fibers. Cement fiber siding and asbestos siding have similar appearances, so before you start tearing into the project, learn how to tell the difference between asbestos siding and fiber cement siding.

What Are the Differences Between Asbestos and Fiber Cement Siding?

When comparing these types of siding, you may notice some visual differences. Fiber cement siding has longer individual boards and a nail pattern on the top of the board, while asbestos siding has shorter boards and a nail pattern on the bottom.

However, these visual differences are subtle. The only way to tell for sure whether you have asbestos siding or fiber cement siding is through testing from a local asbestos testing inspector.

Asbestos Siding vs. Fiber Cement Siding: Differences in Appearance

Asbestos siding and fiber cement siding may look different in a few ways. However, it can be difficult for homeowners to notice these differences themselves, meaning you should rely on testing to know for sure.

Brand Marking

If you can see a stamp on the pieces of siding with the manufacturer’s name, this is a key clue. Companies that manufactured fiber cement board that contained asbestos in the 1980s and earlier include:

• Celotex

• CertainTeed

• Eagle-Pitcher

• GAF Corporation

• Garlock

• Johns Manville

• Keasbey & Mattison

• National Gypsum

Some smaller companies also made asbestos siding, so do an internet search if your siding’s brand is not on this list. Some manufacturers made both asbestos siding and asbestos-free siding. If your siding’s brand marking is from a company that made asbestos siding, you should have a professional test it.

Manufacturing Code

When manufacturers stopped making asbestos siding in the 1980s, they began stamping a code on the back of fiber cement boards to indicate they did not contain asbestos. If you can see the code on a loose piece of your siding, you don’t have asbestos siding.

Faded Colors

Because of its age, asbestos siding will have significant fading. Home builders and siding installers stopped using asbestos siding in the 1980s, so any asbestos siding on your home will be relatively old. 

Chalky Texture

Asbestos siding has a noticeable chalky texture. Painted fiber cement siding can develop a chalky texture as it ages, too, but not always. If you see a chalky texture, you should have a professional test the material.

Length of Siding Boards

Modern fiber cement siding boards can be as long as 12 feet, while older asbestos siding boards are significantly shorter, often maxing out at 6 feet. However, your installer may have chosen shorter fiber cement boards, so you should consider other identifying factors before ruling out a test.

Nail Hole Location

Most asbestos siding boards have nail holes at the bottom of the board. Depending on the brand of fiber cement siding that was installed, the nail holes are more likely to be across the top.

Paint Layers

Because of the age of asbestos siding, previous homeowners may have painted the boards multiple times. Fiber cement siding is newer and requires less frequent painting, so it should have only a couple of layers of paint on it. 

Brittle Material

Asbestos siding becomes quite brittle as it ages, meaning it’ll crack or break off with just a little pressure. Fiber cement siding tends to maintain flexibility as it ages, as long as it’s a high-quality product. Lower-cost fiber cement siding boards may become brittle as they age, though.

Asbestos Siding vs. Fiber Cement Siding: Removal Differences

If testing shows that you have asbestos siding, there are a few different methods to address it. However, it’s more costly and complex than removing regular cement fiber siding. 

Removing Asbestos Siding

Safely removing asbestos siding requires careful action from a professional. Some of the extra steps required to prevent dangerous asbestos fibers from becoming airborne during the siding removal process include:

• Obtaining any necessary permits

• Setting up plastic protective barriers

• Wearing personal protective equipment

• Prying individual boards loose carefully

• Loading debris into enclosed containers for proper disposal

You should not try to remove it on your own. When wondering who to call for asbestos removal for siding, an asbestos abatement professional near you is the best option. These experts have the safety gear and know-how to do the job properly.

If you do not want to remove it, you could cover the asbestos siding with new siding materials. You must follow multiple preparation steps before you can install the new siding layer, though. Because of the danger of releasing asbestos fibers into the air during this process, you should hire a pro to do the work.

Asbestos Encapsulation

If your asbestos siding is still in good condition—it's not damaged or deteriorating—you can encapsulate it instead of remove it.

Asbestos siding encapsulation seals the material in place to prevent release of the dangerous fibers. Asbestos encapsulation is less expensive than removing it, at a cost of about $2 to $6 per square foot.

To encapsulate your siding, an abatement professional will apply a sealant or barrier to create a protective coating. Once complete, you'll still want to check up on it regularly to make sure it's not disturbed. 

Removing Fiber Cement Siding

Removing fiber cement siding is a far easier task than removing asbestos siding. Just pull the nails or screws from each board and pop the board loose. Work your way down the side of the home, taking each overlapping board down.

As long as you're sure the fiber cement siding does not contain asbestos, you don't have to take any precautionary steps to remove it other than wearing safety goggles, a mask, and gloves.