A small hole from a rawlplug, a crack along the door frame, a hairline split near the ceiling — these appear in every flat sooner or later. Before calling anyone, it helps to know what you can fix yourself and what warrants a professional look.
Hole vs crack — why the distinction matters
A hole from a screw or anchor bolt is a local defect — fill it in an afternoon. A crack is a different story. It may be superficial (plaster shrinkage, temperature change) or it may indicate a structural issue. If a crack is getting wider over time, is several centimetres deep, or runs across multiple floors of the building — get a professional assessment before you reach for the filler.
What you will need
- Ready-mixed filler — gypsum-based or polymer
- Steel or plastic filling knife
- Sandpaper (120–180 grit) or a damp sanding sponge
- Primer (for larger repairs)
- Fibreglass mesh tape (for cracks wider than 2–3 mm)
How to fill a wall hole — step by step
1. Prepare the surface. Remove loose plaster and dust from inside the hole. Dampen it with water — dry substrate pulls moisture out of the filler and causes cracking as it dries.
2. For deeper holes, build up in layers. Do not pack all the filler in at once. Fill to two-thirds of the depth first, let it dry (usually a few hours), then top up to the wall surface and smooth flush.
3. Reinforce cracks with mesh tape. Apply the tape along the crack before filling — it stops the crack from re-opening after drying. Apply filler diagonally across the tape to embed it properly.
4. Sand only when fully dry. Do not rush — damp filler just smears. Sand in circular motions and check the surface with a torch held at a low angle to spot any unevenness.
5. Prime before painting. Filler absorbs paint differently from the surrounding plaster — without primer, the repaired patch will show through even after two coats.
Common mistakes to avoid
- Filling without dampening — the filler dries too fast and cracks
- Too thick a layer in one go — the inside stays wet while the surface skins over
- Skipping the mesh tape on cracks — the crack reappears within weeks
- Painting without primer — a visible patch, different sheen from the rest of the wall
When to call a professional
Widespread cracking, cracks that return after repair, or damage accompanied by damp patches and plaster falling away over a large area — these all need a specialist’s eye. In older Warsaw buildings, those symptoms often point to water ingress or a problem behind the wall surface.
If you are not sure about the scope of the repair or want it done right before repainting, leave a request through the form on our site. We will assess the wall on-site and carry out the repair properly. Cost depends on the size of the damage and the type of substrate.