By RenoWorks Hampshire · Published 28/10/2026
Decide whether the defect is cosmetic
A shallow knock from furniture is different from a crack that is widening, recurring or accompanied by sticking doors. Photograph uncertain cracks with a date and ask a competent building professional about movement before filling them. Do not drill or cut into a wall to explore a hole; hidden services may be nearby. Older coatings and textured backgrounds need hazard assessment before sanding or scraping.
Match filler to the background
Check whether you are repairing plaster, plasterboard, timber or masonry. Read the filler's permitted depth, interior or exterior use, working time and finishing instructions. A fine surface filler is not automatically suitable for a deep void, and rigid filler is not a universal answer to a moving junction. Do not fill ventilation openings, drainage paths or essential access gaps simply because they look untidy.
Prepare a small, sound repair area
Protect the floor, clean the area and remove only material that is already loose from an assessed safe surface. Avoid enlarging a hole without understanding what lies behind it. Follow any preparation requirements for the particular filler. Mix only the quantity you can use within its stated working time and use clean tools. Old hardened fragments in a mixing container can drag grooves through a fresh repair.
Apply controlled amounts
Press the material into a shallow defect with a suitable filling knife so it contacts the edges rather than bridging across an empty pocket. Build deep repairs in the stages permitted by the product. Draw the knife over the surface to leave a manageable finish, avoiding a broad unnecessary ridge around the hole. Allow drying or setting as specified; a firm skin does not prove the centre is ready.
Blend the repair before decorating
Once ready, level the repair using the recommended finishing method and remove dust appropriately. Check it with side light and against the wall with a straight edge. Prime or seal the repaired area as the chosen paint system directs, then inspect after drying. If a crack immediately reappears, stop treating it as a filling problem. Keep photographs and ask for an assessment of movement or an unsuitable background.
Related questions
Can decorating caulk replace wall filler?
They serve different purposes. A suitable flexible caulk may suit some small trim junctions; a wall repair may need a sandable filler. Follow the product's substrate and gap guidance rather than using one tube everywhere.
Why is my filled patch visible after painting?
It may be proud, hollow, differently textured or more absorbent than the wall. Let everything dry, check level and preparation, and use the paint manufacturer's recommended treatment for repaired patches.
Further reading
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