How to fill holes and cracks in a wall, step by step

To fill holes and cracks in a wall, clean the area, fill it with filler, let it dry, sand it and only then paint. For small holes, such as wall plug holes, a filling knife and a little filler are enough. For cracks, you need to open them up slightly so the filler goes in properly. The secret is to be patient and apply thin coats.

What you will need

Small holes (wall plugs and nails)

  1. Remove the wall plug or nail and scrape away any rough edges around the hole with the knife.
  2. Wipe off the dust with a dry cloth.
  3. Using the knife, fill the hole with filler. Press so that the filler goes in well.
  4. Smooth the surface with one firm stroke and wipe the knife clean.
  5. Let it dry. Filler shrinks a little as it dries, so you may need a second coat.
  6. Sand lightly until the area is level with the wall.

If the hole is deep, fill it in two or three thin coats. A very thick coat can crack or stay soft inside.

Fine cracks

Fine cracks often appear because of small movements in the building or changes in temperature and humidity. If the crack is only in the plaster or the paint, you can fill it.

  1. Using the tip of a knife or a utility knife, open the crack up slightly into a V shape. It sounds odd, but the filler grips better.
  2. Remove the dust with a dry brush and wipe with a damp cloth.
  3. Apply the filler and press it into the crack.
  4. Smooth it, let it dry and sand.
  5. If the crack is still visible, repeat with a thin coat.

Long cracks or cracks that come back

If the crack is long, or if you have already filled it and it has reappeared, filler alone may not be enough. In this case, stick mesh tape over the crack and cover it with filler. The tape helps to hold the repair together.

Wide cracks, stepped cracks (where one side sticks out further than the other) or cracks near windows and corners may point to a problem with the structure or the plaster. It is a good idea to get a professional's opinion before painting over them.

Large holes

For larger holes, such as those left by an old socket or a large fixing, ordinary filler on its own will not do. First fill the bottom of the hole with a suitable filling material, or a thicker repair filler, and only finish with fine filler.

Sanding and finishing

Once dry, sand with gentle circular movements. Run your hand over it: you should not feel any steps. If you still do, apply another thin coat and sand again. Finally, wipe off the dust with a damp cloth.

Filled areas absorb paint differently from the surrounding wall. If you paint without primer, you may see those areas as duller or flatter patches, even after two coats. So dab a little primer on the repairs only.

Tip: Do not rush to paint. Filler can look dry on the surface and still be damp inside, especially in thick coats or on humid days. Follow the time given on the packaging and, if in doubt, wait a little longer.

See also