Can Andersen Fibrex Windows Be Painted?

Fibrex — Andersen's proprietary composite material, blending reclaimed wood fiber with a polymer — is specifically formulated to be more paint-receptive than pure vinyl window frames, which is one of its stated advantages as a window material. That said, it still has a factory finish that needs proper prep before repainting, following the same core logic as any other factory-finished window material.

1. Why Fibrex is genuinely more paint-friendly than pure vinyl

The wood fiber content in Fibrex gives it more surface porosity and paint receptivity than a purely synthetic vinyl window frame — this is a real, material-level advantage Andersen specifically markets, and it means Fibrex generally needs somewhat less aggressive surface prep than the more paint-resistant pure vinyl or the harder anodized aluminum covered elsewhere.

2. Check the warranty before repainting

As with composite decking, checking Andersen's specific warranty language for Fibrex windows regarding repainting is worth doing before starting — some factory finishes and warranties have specific guidance or restrictions around field-applied paint that's worth knowing about before committing to the project.

3. Clean thoroughly

Wash with soap and water or a degreasing cleaner to remove accumulated dirt, grime, and any residue from the window's years of outdoor exposure and handling.

4. Light sanding or deglossing of the factory finish

Even with Fibrex's more paint-receptive nature, the factory finish still has some sheen that benefits from a light scuff-sand or liquid deglosser treatment before new paint is applied — this remains a worthwhile step rather than an optional one, even though Fibrex needs less aggressive treatment than harder materials like anodized aluminum.

5. Prime with a product compatible with the specific finish

A bonding primer suited to composite or factory-finished window materials gives the new paint a more reliable base — checking for a primer specifically compatible with Fibrex or similar wood-polymer composites, rather than assuming any general-purpose primer performs identically, is worth the extra care given how visible and weather-exposed window frames are.

6. Choosing the topcoat

A quality 100% acrylic exterior paint, in a color within any published guidance from the manufacturer (similar to the LRV considerations covered for PVC trim, since Fibrex also has some heat sensitivity from its polymer content), is the standard topcoat choice.

7. Masking hardware and weatherstripping carefully

Window hardware, locks, and weatherstripping should be masked or removed before painting — paint on functional hardware or weatherstripping can interfere with smooth window operation and sealing, not just look messy, which matters more for a window than for many other painted surfaces given its functional sealing role.