· by Michael Blair, Nashville's Siding
Most fiber cement in Middle Tennessee is James Hardie board, and it leaves the factory one of two ways: primed, waiting for paint, or finished with ColorPlus, Hardie’s baked-on factory color. The question we hear on fiber cement siding jobs is some version of the same thing. Can it be painted, does it have to be, and what goes on it? The answers are in James Hardie’s own documents, and they are more specific than most people expect, including one deadline that catches new construction out.
Can you paint Hardie siding?
Yes, and if it was installed primed, it has to be. The James Hardie FAQ says all Hardie siding is available primed and ready for painting, and that pre-primed board should get an acrylic top coat. The primer is a base for paint, not a finish meant to face the weather on its own.
Board with the ColorPlus factory finish is a different case. It does not need paint, and the same FAQ says it can be repainted if you decide to change colors after installation. The trade-off is that the factory finish carries its own 15-year limited warranty covering paint and labor against peeling, cracking and chipping, while a field coat is covered by whoever made and applied the paint. Hardie also notes that finishes applied in the field can dull substantially over time, which is the main reason people choose ColorPlus in the first place, and one of the choices we walk through before a fiber cement installation.
How soon does primed Hardie board have to be painted?
Within 180 days of installation. James Hardie’s HardiePanel vertical siding installation instructions (HS1237) state that factory-primed products must be painted within that window, and the same wording appears in Hardie’s other installation sheets. Primed siding that sits through a summer and a winter unpainted is outside the instructions the warranty is tied to.
The same sheet sets a few conditions on the work. Every field-cut edge gets caulked, painted or primed, because a raw cut is where the board takes on water. Siding is not painted while it is wet, and when it is sprayed, back-rolling is recommended so the paint is worked into the surface. Here, that last rule matters more than it sounds. Heavy morning dew is common much of the year, so the wall that looks dry from the street at nine in the morning can still be damp on the shaded side, and we wait for it.
What paint goes on fiber cement, and what never should?
A 100% acrylic exterior topcoat. HS1237 recommends it for repainting ColorPlus, and the Hardie FAQ calls for acrylic over primed board. On ColorPlus, the sheet says repriming is normally not necessary, as long as the surface is clean, dry and free of any dust, dirt or mildew.
The list of what not to use is short and firm. HS1237 says not to use stain, oil or alkyd base paint, or powder coating on James Hardie products, and James Hardie’s Homeowner Care & Maintenance Guide repeats the stain and oil-based warning. For a primed wall that was painted after installation, the guide points you back to the paint maker’s own recommendations for when to recoat.
Mildew is the step people skip. North walls and walls under trees here grow it in our humid summers, and paint over it does not hold. The care guide asks for a wash every 6 to 12 months with a garden hose and a soft brush, warns against acid and high-pressure washing, and if a pressure washer is used, calls for a wide fan tip held at least 6 feet from the wall at under 1,500 psi. How we take the green off without harming the finish is in cleaning green mildew off siding.
- Wash the wall and let it dry fully, shaded sides included.
- Re-caulk worn joints at trim and penetrations before painting.
- Use a 100% acrylic exterior topcoat.
- No stain, no oil or alkyd paint, no powder coating.
- Back-roll if the paint is sprayed.
When is it a repaint, a touch-up or a new board?
It depends on the size of the damage and the finish. For ColorPlus, the installation sheet says James Hardie touch-up kits are required, and the FAQ says each kit holds a pint of paint, a touch-up pen and edge sealer. The care guide limits touch-up to nicks, scrapes and nail holes. If the damaged area is larger than a dime, it recommends replacing the section, not painting over it. That is the rule we use after a hailstorm, when ColorPlus walls come back with chips across one elevation; how that kind of loss is handled is in hail-damaged siding and what insurance covers, and replacing single boards is part of our siding repair work.
Caulk is part of every repaint. The care guide says to re-apply it wherever it shows wear, at penetrations and where planks meet trim, using an elastomeric sealant meeting ASTM C920 Grade NS Class 25 or higher, or a latex sealant meeting ASTM C834. Joints at windows and corners are usually on the trim and soffit side of the house, and that is where we look first.
Older houses add one more check. When fiber cement went on over, or next to, older painted wood trim, prep can mean scraping that paint. The EPA’s Renovation, Repair and Painting Program applies to paid work that disturbs painted surfaces in homes built before 1978, and it requires certified firms and lead-safe practices.
If your Hardie siding is due for paint, or you are not sure whether a damaged wall can be touched up, ask for a free estimate. We look at the finish, the caulk and the condition of each board, and tell you which parts need paint and which need replacing.
Sources
- James Hardie, Hardie FAQ — Primed siding takes an acrylic topcoat; ColorPlus can be repainted; 15-year ColorPlus finish warranty; touch-up kit contents; field finishes can dull over time.
- James Hardie, HardiePanel Vertical Siding Installation Instructions (HS1237) — Primed products painted within 180 days; 100% acrylic topcoats; no stain, oil/alkyd paint or powder coating; do not paint when wet; back-roll when spraying; seal cut edges; touch-up kits required for ColorPlus.
- James Hardie, Homeowner Care & Maintenance Guide — Washing interval and pressure-washing limits; no stains or oil-based paints; touch-up only for damage smaller than a dime; caulk specifications.
- U.S. EPA, Renovation, Repair and Painting Program — Lead-safe rules for paid work that disturbs paint in homes built before 1978.
FAQ
Painting Hardie Siding: Primed, ColorPlus and Repaint — questions
Can you paint Hardie siding?
Yes. All Hardie siding is available primed and ready for paint, and primed board should get an acrylic topcoat. Factory ColorPlus siding does not need paint, but James Hardie says it can be repainted if you want a different color later. The paint should be a 100% acrylic exterior topcoat on a clean, dry wall.
How soon after installation must primed Hardie siding be painted?
James Hardie’s installation instructions say factory-primed board must be painted within 180 days of installation. Field-cut edges should be caulked, painted or primed, and the siding should not be painted while it is wet. Leaving primed board unpainted past that window falls outside the instructions the product warranty is tied to.
What is the best paint for Hardie board siding?
James Hardie recommends a 100% acrylic exterior topcoat, both over factory primer and when repainting ColorPlus. Repriming ColorPlus is normally not necessary if the surface is clean, dry and free of dirt and mildew. Stains, oil or alkyd paints and powder coating should not be used on any James Hardie product.
Can you repaint ColorPlus Hardie siding?
Yes. James Hardie says ColorPlus can be repainted if you choose to change colors after installation. Wash the wall, let it dry, and apply a 100% acrylic topcoat; repriming is normally not needed. Small nicks before a repaint are touched up with a James Hardie kit, and a chip larger than a dime means replacing that piece.
Can you stain Hardie siding?
No. James Hardie’s instructions say not to use stain, oil or alkyd base paint, or powder coating on its products, and its homeowner care guide repeats the warning about stains and oil-based paints. Painting the board with a 100% acrylic exterior topcoat is the finish Hardie’s own instructions call for.
How do you touch up scratches on pre-finished Hardie siding?
Use a James Hardie touch-up kit, which holds a pint of matched paint, a touch-up pen and edge sealer; Hardie requires the kits for ColorPlus. Touch-up is meant for nicks, scrapes and nail holes. When damage is larger than a dime, the care guide recommends replacing that section of siding instead.