What sanding is needed between coats of paint on Ottawa interior walls?

Great question -- and one that separates a paint job that looks good on day one from one that still looks flawless five years later. Sanding between coats is a step many homeowners skip, but Ottawa painters treat it as non-negotiable for a professional-grade finish.

Why Sanding Between Coats Matters

Paint doesn't bond to a perfectly smooth, sealed surface nearly as well as it does to one with a slight mechanical tooth. When your first coat dries, tiny imperfections -- dust nibs, roller stipple, dried drips -- get locked in. If you simply roll the next coat over top, those flaws compound and the final surface looks bumpy under raking light. Ottawa's dry winter heating creates static that pulls dust onto wet walls, making this even more of an issue from November through March.

The Right Grit and Technique

For between-coat sanding on drywall, you want 220-grit sandpaper or a fine sanding sponge (3M makes excellent ones in the $6-$9 range at any Ottawa hardware store). The goal is a light scuff, not aggressive material removal:

• Wait for full cure -- latex interior paint needs at least 2-4 hours in a well-ventilated room at 18-22 degrees Celsius. In Ottawa's humid summer months, give it closer to 4 hours. In winter with forced-air heat running, 2 hours is usually sufficient.
• Use light, even pressure in long strokes. You're knocking down nibs and creating micro-scratches for adhesion, not sanding through the coat.
• A sanding pole (about $15-$25 at Home Depot Innes Road or the Hunt Club RONA) saves your shoulders on large walls and gives more even pressure than hand-sanding.
• Wipe down with a tack cloth or damp microfibre after sanding. Every particle of dust you leave behind becomes a visible bump under the next coat.

When to Sand More Aggressively

If your first coat reveals raised drywall texture, visible joint compound ridges, or screw pops, you'll need to address those with 150-grit before moving to 220. Many older Ottawa homes -- particularly in neighbourhoods like the Glebe, Centretown, and Old Ottawa South -- have plaster walls with imperfections that only become visible after the first coat of paint goes on. This is normal and fixable with a skim coat of lightweight compound ($12-$18 per box), a 120-grit sand, then re-prime before continuing.

Primer Coat Sanding

The sand between primer and first topcoat is actually the most important one. Primer is designed to be slightly porous and rough, and a light 220-grit pass smooths it without removing its adhesion properties. If you're using a high-build primer (common for covering texture or old wallpaper residue), you can go to 180-grit on the primer coat since it's thicker.

What Ottawa Pros Typically Charge for This

When you hire a professional painter, between-coat sanding is generally included in the per-room price. For a standard 12x12 room in Ottawa, expect $350-$550 for two coats of quality paint on walls and ceiling, sanding included. That's roughly 10-15% below what you'd pay in the GTA for equivalent work. If a painter quotes you a price and then says sanding is extra, that's a red flag -- it's a fundamental part of the process.

Final Tips

• Never use steel wool between latex paint coats -- fragments can embed and rust, leaving brown spots.
• Don't sand if humidity is above 70% -- the paint may not be fully cured even if it feels dry to the touch. Ottawa's July and August humidity can push indoor levels past this threshold without a dehumidifier running.
• For ceilings, a pole sander is essential. Hand-sanding overhead is exhausting and produces uneven results.
• Between the final two coats, use 320-grit if you want an ultra-smooth finish, particularly on trim and doors.

If you're looking for painters in Ottawa who take sanding and prep seriously, browse the Ottawa Construction Network directory to connect with experienced local painting contractors. And if you've got questions about a specific wall condition in your home, feel free to ask here on Ottawa Paint Contractors' Paint IQ -- we're happy to walk you through it.