How Fiber Cement Siding Is Installed: Steps & Requirements
Fiber cement is one of the most durable siding materials available, but only when it is installed the way the manufacturer requires. Most fiber cement problems, such as cracked boards, failed paint, swollen joints, or water behind the wall, trace back to installation shortcuts rather than the product.
Manufacturers also tie their warranties to their installation instructions, so a careless job can void coverage. TheRemodelers works with licensed siding contractors to help homeowners understand what a correct fiber cement installation looks like, so they can hire well and check the work. For what the material itself costs and how it compares, see our fiber cement siding guide.
Fiber Cement Installation at a Glance
Step | What a Correct Job Looks Like |
|---|
Weather barrier and flashing | House wrap over the sheathing; flashing at every window, door, and roof-wall joint, including kickout flashing |
Clearances | About 6 inches above grade, about 2 inches above roofs, decks, and walkways, and a small gap above horizontal flashing |
Fastening | Blind nailing (hidden by the course above) is preferred for lap siding; nails snug, not overdriven |
Butt joints | Boards in moderate contact with joint flashing behind them, or treated as the instructions specify |
Cutting | Dust-controlled tools and respirators for crystalline silica |
Cut edges | Sealed with caulk, paint, or primer |
Painting | Primed boards painted with 100% acrylic paint; James Hardie requires within 180 days |
Before Installation: Handling and Product Choice
Fiber cement boards are heavy and can crack if handled carelessly. They should be stored flat, off the ground, and covered. Installing boards that are wet or saturated can lead to shrinkage at the butt joints as they dry.
Confirm the product suits your climate. James Hardie sells climate-specific "HardieZone" versions and states that installing a product outside its zone voids the warranty.
How Fiber Cement Siding Is Installed
1. Weather Barrier and Flashing
A water-resistive barrier, usually house wrap, goes over the sheathing as building codes require. Flashing goes around every window and door and at every roof-to-wall intersection.
Kickout flashing at the bottom of each roof-wall joint is critical, because it diverts the water running off the roof away from the siding instead of behind it. For the full set of parts behind a siding job, see our guide to parts of a siding system.
2. Clearances
Fiber cement must not sit in water or touch the ground. Typical requirements are about 6 inches between the bottom of the siding and finished grade, about 2 inches above roofs, decks, and walkways, and a small gap above horizontal flashing. Check the manufacturer’s instructions and your local code for the exact figures.
3. Starter Strip and First Course
A starter strip at the bottom of the wall sets the angle and level of the first course. If it is off, every course above it will be off too.
4. Fastening
Lap siding is fastened into the wall framing with corrosion-resistant nails. Blind nailing, where the nail is hidden by the course above, is James Hardie’s preferred method for its lap siding; face nailing is used in some situations, such as high-wind zones.
Nails should be snug against the board, not overdriven, since a sunk nail head weakens its hold. Spacing and placement follow the manufacturer’s fastening schedule.
5. Butt Joints
Where two boards meet end to end, they are installed in moderate contact. James Hardie recommends joint flashing behind each butt joint, which keeps water off the wall without relying on caulk. Some products and finishes allow caulked joints instead; the instructions say which.
6. Cutting and Dust Control
Cutting fiber cement releases crystalline silica, which is hazardous to breathe. Crews should use shears, score-and-snap tools, or saws with dust collection, work outdoors, and wear respirators that meet NIOSH requirements.
Every cut edge should be sealed with caulk, paint, or primer so it does not absorb water.
7. Trim and Corners
Corners, windows, and doors get trim boards, with the siding finished against them according to the manufacturer’s details. Gaps between siding and trim are sealed with a quality exterior sealant where the instructions call for it.
8. Painting and Touch-Up
Primed boards are painted with a quality 100 percent acrylic exterior paint; James Hardie requires its primed products to be painted within 180 days and does not allow stain or oil-based paint.
Factory-finished boards need only touch-up on nicks, cut edges, and scrapes. On factory-finished products, nail heads are not caulked.
Common Installation Mistakes
Siding touching the ground, roofs, or decks without the required clearance
Missing kickout flashing at roof-wall intersections
Overdriven nails or wrong fasteners
Butt joints without flashing or proper treatment
Unsealed cut edges
Installing wet boards
Leaving primed boards unpainted too long
Using a product made for a different climate zone
How Long Installation Takes
On a typical 2,000-square-foot home, fiber cement takes about 5 to 10 days, longer than vinyl because the boards are heavy, cutting is slower, and fastening is precise. On-site painting adds 1 to 3 days. For timelines by material, see how long siding installation takes, and for what each day looks like, our guide to the siding installation process.
Can You Install Fiber Cement Yourself?
It is not a beginner project. The boards are heavy and brittle, cutting requires silica dust control, and the warranty depends on following detailed clearance, flashing, and fastening rules. Most homeowners are better served hiring a crew that installs it regularly. See DIY siding installation vs. hiring a contractor for how to decide.
Questions to Ask Your Installer
Are you certified by the manufacturer, and do you follow its installation instructions?
Which nailing method will you use, and what fasteners?
How will you treat butt joints?
What clearances will you keep at the ground, roofs, and decks?
Will you install kickout flashing at every roof-wall intersection?
How do you control silica dust?
Who paints primed boards, and when?
What labor warranty do you offer on the installation?
Final Thoughts
A fiber cement job lasts decades when the details are right: a proper weather barrier, kickout flashing, correct clearances, careful fastening, flashed joints, sealed edges, and timely paint. Knowing those details lets you ask the right questions and spot shortcuts before they cost you. For guides on every siding material, visit our siding project hub.
Want installers who do it right? Home Upgrade Pros connects homeowners with licensed, experienced siding contractors for free estimates, or call (725) 745-8553 to set one up.
Frequently Asked Questions
Is fiber cement siding blind nailed or face nailed?
Blind nailing, hidden by the course above, is James Hardie’s preferred method for its lap siding. Face nailing is used in some situations, such as high-wind areas, as the instructions specify.
How far above the ground should fiber cement siding be?
Typically about 6 inches above finished grade, and about 2 inches above roofs, decks, and walkways. Check the manufacturer’s instructions and local code.
Do fiber cement butt joints need caulk?
Not necessarily. Boards meet in moderate contact, and James Hardie recommends joint flashing behind each butt joint. Some products allow caulked joints; the instructions say which.
How soon does fiber cement siding need to be painted?
James Hardie requires its primed products to be painted within 180 days of installation, using 100 percent acrylic paint. Factory-finished boards need only touch-up.
How long does fiber cement installation take?
About 5 to 10 days on a typical 2,000-square-foot home, plus 1 to 3 days for on-site painting.
Can fiber cement be installed over old siding?
Usually not. Fiber cement generally requires removing the old siding so it can be fastened properly and the weather barrier and flashing can be done right.
