What Is Hardie Board?
Independent — we don't sell or install siding · Last updated September 2026 · Data as of August 2026
The short answer
Hardie board is James Hardie's brand of fiber cement siding: boards made from cement, sand and cellulose (wood) fibers, formed into planks, panels and shingles that look like painted wood. It won't burn, rot or feed termites, lasts about 30 to 50 years, and costs roughly $6–$14 per square foot installed.
What Hardie board is made of
Four ingredients: Portland cement for hardness, sand (silica) as filler, cellulose fibers from wood pulp for reinforcement, and water. The mix is formed into boards, pressed with a smooth or wood-grain face, and cured. The fibers are what stop a thin cement board from snapping — and what replaced the asbestos fibers used in cement siding decades ago.
“Hardie board” is the brand name; fiber cement is the material. James Hardie is by far the largest maker, so the terms get used interchangeably. It also sells climate-specific formulations (HardieZone HZ5 for freeze-thaw regions, HZ10 for hot, humid ones).
Hardie product lines and finishes
| Product | What it is | Installed / sq ft |
|---|---|---|
| HardiePlank | Horizontal lap siding — the product most people mean by “Hardie board.” Smooth or wood-grain faces, several widths. | $6–$12 |
| HardiePanel | 4 × 8 ft and larger vertical sheets, often with battens over the joints for board and batten. | $6–$12 |
| HardieShingle | Shingle-look panels and individual pieces for gables and accents. | $8–$14 |
| HardieTrim / HardieSoffit | Matching fiber cement trim boards, fascia and soffit, so the whole exterior shares one material. | Priced per linear ft |
Every line comes in two finishes, and the choice matters more than it looks:
| Primed (field-painted) | ColorPlus (factory finish) | |
|---|---|---|
| Extra cost | Painting ≈ $1.50–$4 / sq ft (plus repaints) | ≈ $0.75–$2 / sq ft over primed |
| Next repaint | ≈ every 12 years | 15+ years (finish warranty) |
| Colour choice | Any paint colour | The factory palette |
How Hardie board goes on the wall
HardiePlank is hung one course at a time over a water-resistive barrier, each plank lapping the one below and nailed where the next course hides the nail. The details in the drawing are the ones that decide whether it lasts 30 to 50 years or fails early.
- 1Wall framing and sheathing.
- 2Water-resistive barrier (housewrap or felt) — the real waterproofing layer; siding only sheds most of the rain.
- 3HardiePlank: about 5/16″ thick, the same thickness top to bottom, hung one course at a time.
- 4Blind nail near the top edge, hidden by the next course — the preferred method.
- 5Minimum 1¼″ lap over the course below.
- 6A starter strip kicks the first course out to the same angle as the rest.
- 7At least 6″ above finished grade, with the ground sloping away.
- 8Butt joints are staggered and backed with a strip of joint flashing.
Two clearances don't fit in the drawing: keep the bottom edge about 2″ above roofs, decks, patios and driveways, and leave a ¼″ gap above horizontal flashing that is not caulked shut. Where siding meets a roof, a kickout flashing sends water away from the wall. These are the points a warranty claim is judged on.
Pros and cons
Pros
- Non-combustible — suits wildfire areas
- Won't rot, swell or feed termites
- Convincing painted-wood look; crisp lines
- 30 to 50-year life; 30-year board warranty
- Most siding crews know it
Cons
- Costs more than vinyl, and labor is a big share
- Heavy; not a DIY material
- Silica dust when cut
- Needs repainting unless ColorPlus
- Unforgiving of sloppy installation
What Hardie board costs and how long it lasts
Planning range: about $6–$14 per square foot installed, of which $2.50–$5 is material. It typically lasts 30 to 50 years. James Hardie backs the board with a 30-year non-prorated warranty and ColorPlus finishes with a separate 15-year finish warranty — both conditional on installation to its instructions. Totals by home size are on the fiber cement siding cost page; what the warranty excludes is in the warranty checker. For whether the brand is worth it, see our James Hardie siding review.
When Hardie board is the wrong choice
Fiber cement is a strong default for a long-term home, which is exactly why it gets recommended where it doesn't fit. Skip it when:
| If… | Consider | Why |
|---|---|---|
| You'll sell within about five years | Vinyl | Fiber cement runs $6–$14/sq ft installed against $4–$12 for vinyl; a short hold rarely earns the gap back. |
| You plan to install it yourself | Vinyl | Planks are heavy and brittle before they're fastened, cutting makes silica dust, and the warranty depends on installing to James Hardie's instructions. |
| Hail is the main threat and you want a painted-wood look | Engineered wood | Engineered wood takes impact better; fiber cement can chip or crack at edges and corners. |
| You never want to repaint and won't pay for ColorPlus | Vinyl | Field-painted fiber cement needs repainting about every 12 years; vinyl never does. |
| A historic review requires real wood | Wood clapboard | Some districts accept fiber cement, many don't — ask before you price it. |
| Your installer hasn't hung much fiber cement | A different crew | Most Hardie failures trace to clearances, flashing and fastening, not the board. |
Weighing it against the other wood-look option? LP SmartSide vs Hardie. Against the budget option? Vinyl vs fiber cement.
Cutting it safely: silica dust
The sand in fiber cement is crystalline silica, and cutting, grinding or sanding boards releases respirable dust that can scar the lungs with repeated exposure. OSHA's construction silica standard lists fiber-cement saws specifically: cut outdoors with a saw fitted with a dust-collection system. Score-and-snap tools and shears make far less dust than a bare circular saw.
If a crew is dry-cutting Hardie board with an ordinary saw in a cloud of dust next to your open windows, that tells you something about the rest of the install too.
Is Hardie board asbestos?
No. Modern fiber cement uses cellulose fibers. But a different, older product — asbestos-cement siding, usually rigid 12 × 24-inch shingles — was common on houses built or re-sided from about the 1920s to the 1980s and looks similar. If your house is that age and has cement shingles, test before cutting or removing anything: asbestos siding: test, cover or remove.
Where to go next
Fiber cement comes as lap, clapboard and board and batten, and it's a strong pick for cold climates. Not sure it's the right material? The siding selector checks it against your house.
Keep going
Frequently asked questions
- Is Hardie board the same as fiber cement?
- It's a brand of fiber cement — the biggest one, so its name gets used for the whole category. Other brands are the same basic material.
- What's the difference between Hardie board and cement board?
- Hardie siding is exterior cladding. Cement board — including James Hardie's HardieBacker — is a backer panel for tile indoors. Different products; not interchangeable.
- What are the downsides of Hardie board?
- Higher installed cost, heavy and crew-dependent, silica dust when cut, repainting unless you buy ColorPlus, and it fails when clearances and flashing are skipped.
- Is Hardie board better than vinyl?
- Tougher, non-combustible and more wood-like; vinyl is cheaper and paint-free. Vinyl vs fiber cement
- Is Hardie board better than wood?
- On rot, fire, termites and repaint interval, yes. Real wood still wins on authenticity. Fiber cement vs cedar
- Does Hardie board contain asbestos?
- Modern Hardie board doesn't — it uses wood fibers. Older asbestos-cement siding (about the 1920s–1980s) is a different product. Asbestos siding
- How long does Hardie board last?
- Typically 30 to 50 years, with a 30-year non-prorated board warranty; the paint is what needs renewing.
Cost figures are independent 2026 planning estimates and vary by home, region and installer. Installation details summarise James Hardie's published instructions; always follow the current version for your product.