A wonder siding: Fiber cement could be your home's best option

This Old House
A wonder siding: Why fiber cement might be your home's best option
.

View photo

This siding looks like wood clapboard, but it's fiber cement from CertainTeed.

Picking the right siding for your house is a delicate balancing act between good looks, durability, maintenance and affordability. With wood, vinyl, stone, brick or stucco, you might get only two or three of these. But with fiber cement, a resilient mix of wood pulp and portland cement, you get all four. It's the only siding that combines the performance of masonry—minimal upkeep; rot-, fire-, and termite-proof; unaffected by wind or cold—with the look of painted wood clapboards, shingles, even stone or brick.

Yet fiber cement goes for just a fraction of the cost of these other materials (except vinyl; more on that in a moment). No wonder nearly 15 percent of new homes are clad with the stuff. Read about the basics of fiber cement here on Yahoo! Homes, then go to This Old House to learn even more.

THE VITALS

What's it made of? The basic recipe for fiber cement has just four ingredients: water, which dissolves the wood pulp and activates and hardens the cement; wood pulp, which improves flexibility and resilience; fly ash, which acts as a filler (some makers use silica sand instead); and portland cement, which binds the ingredients and is made with limestone, clay and iron.

What's it cost? Fiber cement averages about $1.70 a square foot, depending on finish, size, and where it's sold. That's compared with wood, brick or stone at around $5 to $10 a square foot or aluminum or stucco at around $3 a square foot. Vinyl siding beats out fiber cement in terms of price (70 cents a square foot) as well as popularity (vinyl has about twice the market share). But vinyl is vulnerable to fire and high winds, and it doesn't mimic the wood look as well as fiber cement does.

DIY or hire a pro? Because of its weight—about 2½ pounds per square foot—its tendency to crack if mishandled, and the specialized tools needed to cut and nail it, fiber-cement installation is best left to pros.

[Need help installing siding on your house? Click to find the right contractor now.]

How long does it last? Warranties against defects range from 25 years to limited lifetime. Factory finishes carry a 15-year warranty against flaking and fading.

How much care does it need? As with wood siding, spray it with a garden hose every 6 to 12 months; inspect caulked joints every few years, and be sure to keep foundation plants pruned back so that siding can dry out.

FINISH AND TRIM

Fiber cement has to be painted or stained. This can be done before it's installed—either by the manufacturer or by a paint shop hired by the lumberyard where you order the siding—or after it's up. Manufacturers charge about $1 per square foot and offer a 15-year warranty, but color choice is limited and you get only one coat. Paint shops provide two coats, 25-year warranties, and hundreds of hues for about $2 per square foot, not including the cost to ship your order to and from the lumberyard. On-site painters generally offer one- or two-year warranties on their work.

For minimal maintenance, use trim made of fiber cement or cellular PVC. Both are rot-proof and come in standard ¾- and 1-inch thicknesses for use as corner, frieze and fascia boards. Crown moldings are also available. You can also use wood trim with fiber-cement siding. Wherever trim and siding meet, there should be a 1/8-inch gap, concealed with caulk.

LAYOUT AND INSTALLATION

Fiber-cement panels butt together at the edges, making layout a no-brainer. With clapboards and shingles, each course overlaps the next by at least 1¼ inches. The portion that's visible—not overlapped—is called the exposure. (A 6¼-inch-wide clapboard with a 1¼-inch overlap has a 5-inch exposure.) Exposure has to be decided before you order because it determines how wide your siding will be, how much you will need, and how it will look once it's installed.

Make sure your contractor uses rustproof stainless-steel nails, primes all cuts, and caulks joints with a paintable exterior-grade sealant that will remain flexible. To reduce water absorption, fiber cement has to be installed at least 2 inches above steps, decks, and roofs, and at least 6 inches above grade. Check joints every few years and recaulk as needed.

[Thinking about installing new siding on your home? Click to find the right contractor now.]

(Credit: This Old House)

(Credit: This Old House)

HOW MUCH
TO BUY

The calculation varies based on the type of siding.

For panels, simply divide the total square footage of your exterior walls—including windows and doors, which account for waste—by the number of square feet in one piece.

There isn't an easy equation for shingles, so it's best to have your supplier do the math.

For clapboards, use the formula shown here, which factors in how much of each board is exposed.

FIBER CEMENT VS. MOTHER NATURE

This durable material outperforms many of its siding competitors in a range of climates.

Out west: In arid locales that are prone to wildfires, particularly in the western U.S., some insurance companies offer a discount for homes sided in fiber cement because it's noncombustible. It's also unaffected by the strong UV radiation typical at high altitudes.

On the coast: Salt air, high humidity, and bright sun are constant challenges in seaside environments but have no effect on this siding. With a proper nailing pattern, it will also withstand winds up to 130 mph.

Down south: Termites and fungi thrive in the warmth and moisture of the southeastern U.S., such as in New Orleans, but they get no nourishment from fiber cement.

Up north: Unlike vinyl, fiber cement doesn't become brittle in cold weather. It easily withstands below-zero temperatures and won't crack because of freeze-thaw cycles.

Read more about fiber-cement siding at ThisOldHouse.com.

View Comments