How to fill cracks and holes before painting.

5 min read · Sandwich Painter

Helpful video reference. The video above is "How To Fill Cracks and Holes In Walls Before Painting" from Paint Like A Pro, demonstrating the cleaning, filling and sanding sequence described above.

Clean the crack or hole before filling

Lightly sand or scrape any loose material, flaking paint, or crumbling plaster out of the crack first, filler applied over loose debris will fail as soon as that debris shifts underneath it. Wipe away dust with a damp cloth and let the area dry fully before filling.

For small nail and screw holes this is quick, but for hairline cracks caused by settlement or movement, it's worth opening the crack very slightly with a scraper first so the filler has something to key into rather than just sitting on the surface.

Choose the right filler for the job

A standard non-shrinking filler works for small holes and minor cracks on plaster or drywall. For a genuine structural or movement crack (as opposed to a cosmetic surface one), a flexible filler designed to accommodate slight ongoing movement holds up better than a rigid one, which can crack again along the same line.

Apply with a putty knife, slightly overfilling proud of the surface since most fillers shrink a little as they dry. A single thin skin rarely fills a deeper crack properly, better to build it in two thin passes than force one thick one that cracks as it cures.

Sand smooth and prime before painting

Once fully dry, sand the filled area smooth and flush with the surrounding wall using medium-grit sandpaper, checking by running a hand over it rather than relying on sight alone, uneven filler shows clearly once paint's on.

Spot-prime the filled patch before the main coats. Filler is more absorbent than the surrounding painted surface, and skipping the primer step is the most common reason a filled patch shows through as a slightly different sheen once the topcoat's dry.