What roller nap thickness should I use for different surfaces when painting walls and ceilings?

Roller nap thickness — also called pile or nap length — is matched to surface texture: smooth surfaces need short nap (6-10mm), standard drywall walls need 10mm (3/8 inch), and rough or textured exterior surfaces need 15-20mm (5/8 to 3/4 inch). Getting this right is one of those small details that separates a professional-looking result from a frustrating, uneven one.

Smooth surfaces — cabinets, interior doors, trim, and furniture — need a 6mm (1/4 inch) micro-fibre roller or foam roller. The short, tight nap lays paint on smoothly without adding texture. Even a small amount of extra nap on a cabinet door will leave a stippled orange-peel texture you will see every time light catches the surface. If you are rolling trim or cabinet doors and want a near-spray finish, a 4mm foam roller is the right tool.

Standard interior walls — drywall, plaster, and previously painted surfaces in good condition — are best covered with a 10mm (3/8 inch) nap. This is the most common roller in NB painters' kits, and it works well for flat, eggshell, and satin latex paints on most residential walls. It holds enough paint to cover efficiently without depositing so much texture that the wall looks rough. If your walls have light texture (common in many 1980s-1990s NB homes with a light knockdown or orange-peel finish from the builder), a 12-13mm roller gives a little extra paint to fill the valleys.

Ceilings — especially stippled or acoustic ceilings common in NB homes — need at least a 15mm (5/8 inch) nap, and sometimes 18-20mm for heavily textured stipple. A short-nap roller on a stippled ceiling barely touches the raised peaks without filling the valleys, leaving an uneven, streaky finish. The longer nap presses deep into the texture for full coverage. Be prepared for more spatter with longer nap on ceilings — use a good drop cloth and wear a hat.

Exterior surfaces — clapboard siding, cedar shingles, rough-sawn wood, concrete block — need a 18-20mm (3/4 inch) nap to push paint into the irregular surface. NB clapboard siding especially has grooves, laps, and rough wood that swallow paint quickly. A short nap roller will skim the surface without penetrating into gaps, leaving bare wood in crevices that will allow moisture infiltration and paint failure within a season or two.

Always buy roller covers that match your paint type. Cheaper polyester covers work adequately for latex paints. For alkyd or oil-based paints (now rare for interior use but still used for trim in some older NB homes), use a lambswool or natural cover. Many paint stores in Moncton and Fredericton stock Purdy and Wooster roller covers — these hold more paint, shed less lint, and give a more uniform texture than budget covers.

When to hire a pro: If you are painting ceilings with stipple or other texture, getting the roller nap right is critical for even coverage. Professional painters often have an extensive selection of roller covers and know which works best for each surface — their experience with NB housing stock across different construction eras makes a real difference in the final result.

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