Repair of cracks and voids in plaster


After removing the paint and cleaning the walls and ceiling, you need to check, if there are no cracks or gaps in the plaster. Most of the problems appear at the preparation stage, however, some may be invisible at first. A frequent problem is plaster detaching from the wall. When we knock on such a place with a finger, we will hear a characteristic empty sound. It would be best to chuck off the protruding fragment and patch the resulting hole with new material, for example, gypsum putty. Admittedly, plastering a room is a complicated job, requiring a lot of skill, it is quite easy to repair minor cavities by yourself.

Gaps between woodwork and walls

Usually quite a few cracks in the plaster are in places, where the wall meets the door and window frames. Gaps also appear between the walls and baseboards. They are usually caused by the movements of the wood, when the indoor humidity and temperature change. Use a small spatula to remove any loose material from cracks and cracks, and then we fill them with acrylic sealant dispensed with a gun. This preparation withstands small deformations much better than putties. The filler must touch both surfaces of the fracture. If it is very broad, you can insert a piece of wood or polystyrene in the appropriate shape.

Cracks between the wall and the ceiling

The contact points of walls and ceilings rarely remain without cracks, and this is due to slight movements of the building. The easiest way to patch them with acrylic sealant. However, the best solution may be to use stucco or other decorative elements, which will cover them. Stucco is available in many types and sizes. They are most often made of plaster or polystyrene, painted or ready to be painted.

Cracks and cavities in the walls

Fill small cracks with acrylic putty, and bigger – plaster, in the form of a paste or a dry mix (tooth. pictures on the opposite page). If we use a dry mix, clean water is used to mix plaster.

After each use of a plaster, the vessel should be thoroughly cleaned, in which the material was processed, because the residues remaining in it shorten the setting time of subsequent batches and thus weaken them.

If the cracks are large or deep, we fill them in in stages. Subsequent layers, they should not be thicker than a centimeter. The surface of each of them should be scratched, so that the next one is easier to bond with it - we put it on, when the previous one has hardened, but not completely dry yet. Let's remember, that a place covered with plaster absorbs more paint or wallpaper glue than old plaster, so they need to be primed before painting 1-2 layers of universal primer.

If we have to fill a large hole in the wall, stuffing it with putty will be a waste. It is best to insert pieces of brick into the hole and grout the gaps, which will record the whole – small 5 kg packages of cement for such small works are already available. So it is not necessary to buy large ones, 25-kg of bags. When we fill the hole to the depth 5 cm from the wall surface, you can apply a cement-lime or gypsum mortar.

If we are plastering large surfaces, it is good to attach temporary guiding rails to the wall. This will allow you to keep an even surface throughout the summer. Before the plaster is completely set, we remove the slats and fill the grooves with plaster, to be equal to the rest of the summer.

Filling the crack

1 We begin by carefully removing any loose material from the inside of the crack with a spatula or knife.

2 Use a small brush to soak the crack with water or a universal primer. This will protect the putty against drying too quickly.

3 We apply the mass with a spatula in small portions. We press it into the crack. We repeat this action, until the crack is gone. The putty should protrude slightly above the wall surface.

4 We leave the mass to harden, and then sand its excess with fine-grained sandpaper or a trowel with a stretched abrasive mesh.

Patching drywall

1 We cut dad a little larger than the hole to be patched. We tie a string to the pushpin and thread it through the hole in the dad. We put gypsum glue on the edges.

2 We put the cut piece through the hole in the plate and pull the string tightly, until its surface is flush with the surface of the plate. When the plaster solidifies, cut off the string and fill the resulting hole.

3 To fix the corner, nail a wooden strip on one side flush with the corner and fill the other part with plaster.

When the plaster hardens, we change the position of the slat and repeat the operation on the other side of the corner.