How To Cut and Install Fiber-Cement Siding

Fiber-cement siding combines the strength of cement with the flexibility of wood fibers, resulting in a product that’s more durable and cost-effective than traditional wood varieties. It also has natural insulating properties, so many homeowners use it to improve their energy efficiency.

Watch This Old House‘s Tom Silva and Kevin O’Connor demonstrate cutting and installation techniques for fiber-cement siding, and learn some tips on how to keep it looking at its best.

Why Install Fiber-Cement Siding?

Fiber-cement siding offers several advantages over traditional siding materials, including these:

• Cost-effectiveness: Fiber-cement materials are about 30% to 40% less expensive than cedar and redwood.
• Durability: Fiber-cement siding is a hard material that withstands dents and impacts.
• Energy-efficiency: Fiber-cement can help keep heat and cool inside your home in the busy seasons. By cutting down on how much work your HVAC system has to do, you could save more on your energy bills.
• Versatility: You can find fiber-cement siding in various finishes, ranging from wood grain to smooth.
• Low maintenance: The paint finish applied at the factory can last 10–20 years, so you won’t need to repaint it as often.
• Resilience: Cement used in the siding provides excellent fire protection for your home. It also makes your home’s exterior less susceptible to damage from wood-boring insects like termites.

Safety Precautions When Installing Fiber-Cement Siding

Fiber-cement siding is made from a mixture of cement, cellulose fibers, and sand, which can create fine dust particles when it’s cut. Inhaling the dust, even inadvertently, can harm your health. It’s best to take these safety precautions when you work with it:

• Use eye protection to guard against flying debris.
• Wear a dust mask or respirator when cutting so you don’t breathe in the dust.
• Wear gloves to protect your hands from the abrasive material.

Cutting Fiber-Cement Siding

To cut fiber-cement siding, you’ll need specific techniques that improve precision and minimize dust. Which method you use will depend on your dust control preferences and your project’s scale.

Circular Saw Method

Using a circular saw is a common and accessible way to cut fiber-cement siding. Use a blade with only four or six teeth, designed specifically for fiber cement. Mark your lines, put on your safety equipment, then cut slowly and steadily. Don’t try to force the saw through the material—instead, let the blade do the work for you. 

To minimize dust, Silva grabs a 5-gallon bucket and connects the saw to it with a specially designed hood. The saw’s fan directs dust through a hose and into the bucket. If that sounds too complex or you’re only making a few minor cuts, you can also attach a dust collection bag to your saw.

Power Shears Method

Power shears are a bit slower to use, but they can help you make straight cuts while generating barely any airborne dust. Sometimes, the shears are their own tool. Other times, you attach them to a drill/driver. Either way, they’re ideal for working in tight and enclosed spaces.

As you cut, follow your marked line. Support the siding properly so it doesn’t crack or chip.

Fiber-Cement Siding Installation Techniques

With your siding cut, you’re ready to start installing. Follow these instructions to do the job well:

Preparing the Surface

There’s no such thing as too much when it comes to protecting your home from water damage. Plan your layout to use materials efficiently and minimize seams. Then, before you start nailing away, prepare the area by installing a weather barrier over the wall surface. Apply metal flashing around windows, doors, and other openings.

Nailing Techniques

Proper nailing makes your installation more secure. You can hand-nail or use a nail gun for the job, but do not overnail. This can weaken the structure of the panels and compromise their durability.

If you’re hand-nailing the siding to your wall, use hot-dipped galvanized nails. Don’t drive the nail heads below the siding surface.

For larger projects, or if you’d rather work a little faster, you can use a pneumatic nail gun. Opt for ring-shank stainless steel nails that are more likely to stay secure. Adjust the depth setting so the nails go in flush with the surface. 

Caulking

Caulking seals your siding’s joints so water can’t get inside. Leave a small gap at the ends of each siding piece for the caulk so the siding and trim can still expand and contract with the rest of your house.

Apply caulk to the joints both before and after you install the siding. Place flashing behind all end joints where two pieces of siding meet, and confirm that each piece overlaps the siding course below so water can drain properly. 

Painting and Finishing

Many fiber-cement products come pre-primed, pre-painted, or both. However, a touch-up or two may still be necessary.

To protect your siding’s finish, use a type of paint that the manufacturer recommends for touch-ups. Apply it to the cut edges to prevent moisture absorption.

Maintenance

To keep your fiber-cement siding looking its best, clean it at least once yearly with a soft brush and mild detergent. Inspect for any loose or damaged sections as you go, and reapply caulk to joints as necessary to keep the seal watertight.