Repair of old plaster

But first, we need to take a close look at the facade before jumping to its defense. Traditional plasters peel, crack, and become dirty after many years of use. The kind and degree of coating damage determines the best course of action for surface repair. The damage assessment should ideally be completed by a specialist who can identify the type and state of any paint coating, as well as the plaster’s strength, load-bearing capacity, and absorbency.

Abrasion and peeling of plaster

Places where the plaster peels off from the gypsum base (colloquially called rubbing).) the acoustic method is searched for by tapping on the facade with a hammer. When the plaster is “deaf” or comes off when hit, it needs to be chipped. If there are few such poorly held pieces of plaster, you can be content with small, local additions to the expedition. However, if the plaster is rubbed on a large area, then there will be no need for its local pothole repair – then it is better to decide on a comprehensive repair of the entire.
Whether we are repairing the entire plaster or repairing it on site, we must remember that the exposed wall must be primed with an emulsion, which reduces its absorbency and improves the adhesion of the new layer of plaster.

How to repair a facade?

Applying new plaster so that the junction with the old one is not visible, and matching the color of the new layer to the one that remained on the facade and was exposed to sunlight for years is a very difficult task, almost impossible. . Usually after renovation the facade does not look good. Its surface must be uniform so that the new and old pieces of plaster form a single whole. This is best done by filling entire walls with a contact mortar containing short elastic fibers (often the same reinforcing mortars used in insulation systems) and embedding a mesh into them. The putty layer should be 3-4 mm thick. If you skillfully erase it, it resembles a fine -grained stucco molding. It can be painted or covered with thin -layer decorative plaster.

Watch the video to see how to create a low-cost, brick-like facade with your own hands.

Any damage to the plaster must be removed before painting the facade. If not, the repair will not hold up.

Pleshin coat

Because of the dampness of plaster, they appear there; consequently, their causes must be identified and removed. Poorly made castings, leaky gutters, window sills without sill plates, inadequate wall-to-balcony sealing, flimsy basement plaster, and moisture-sensitive paint are a few examples. After using a hard brush to eliminate any mold, apply fungicide to clean the plaster, let it dry, and apply paint.

Examination of paint

To be able to assess the condition of the old paint coating, the walls should first be washed with water under pressure (it should have the highest possible temperature – the maximum permitted by the manufacturer of the device) or with steam. In addition to removing all contaminants such as dust, grime, soot, bird droppings, flowers and algae, it also exposes all weak points and removes paints that are not sufficiently bonded to the plaster and are not water-resistant.
Once the wall has been washed and dried, the adhesion of the façade paint to the plaster can be assessed. It is a shallow cut of a small surface of the plaster in a checkerboard pattern.
A very sharp tool (e.g. a wallpaper knife) is used for cutting .If the chips along the cuts are small or absent, then the paint adheres well to the plaster. If the paint does not adhere well, then even whole cut squares of the checkerboard (5×5 mm) will fall off. Then it must be completely removed (scraped off with a spatula or sanded).
The dust-free, cleaned, repaired and primed plaster is repainted again. Usually it is necessary to paint the entire wall, since the new paint, if applied only locally, will be too different from the old, faded coating.

Scattering and sprinkling plaster

Poorly made plaster eventually exfoliates ("sands") or gets dusty if, for example, there was too little binding in it or the binding was filtered, too long, or too dry. As a result, you must apply a primer to it, strengthening the surface. These medications are used on the already-washed exterior.

Moisture

Water vapor should be avoided, but the facade plaster should not get wet. Sadly, plastered mixtures made on the job site—that is, "squeezed" mixtures made of sand, cement, lime, and water in a concrete mixer—do not have waterproof properties; the only sources of waterproof plasters are contemporary dry mixtures made in factories. It is possible to coat outdated plasters with a unique liquid that repels water. It is important that you carefully follow the manufacturer’s instructions because too much liquid can affect the plaster’s vapor permeability and adhesion, making future painting impossible.

Scratches and cracks

The appearance of scratches on the plaster means that sooner or later we will have new problems (moisture can penetrate deep into the wall, which will lead to further damage). Therefore, cracks in facade plaster should be repaired as quickly as possible.
When scratches appear? Simply put – when the plaster cannot behave as desired. That is, when its deformations were caused by something. Therefore, scratches occur as a result of swelling or shrinkage of the base (for example, plaster on walls made of materials that swell under the influence of moisture), poor preparation of the walls before plastering, or the use of too strong plaster. The plaster can be scratched on the surface or cracked throughout its thickness.

Repairing cracks that arise solely from stress and compression in the plaster layer—that is, not from wall cracks—is relatively easy. The scratches from relatively insignificant damage and plaster flaws are shown below:

• baggy – usually runs horizontally in the form of a bulge about 20 cm long and 3 mm wide;
• mesh about 0.5 mm wide, form a grid image with a distance between nodes of about 20 cm;
• shrinkage – they have the form of a grid or web, partially reaching the ground, which often leads to peeling of the plaster.

It is more difficult to fix scratches:

• diagonal – runs diagonally, in the corners of window and door openings;
• groove – appear in the joints of the walls, resulting in deformation of the outer layer of the wall structure or a bad joint. These are more difficult to repair, since they are due to the characteristics of the base;
• Structural

Caused not by cracks in the building, but, for example, by its uneven shrinkage, they appear in the area of ​​the ring rims in the form of one or two long cracks with a direction corresponding to the structure of the building. They arise as a result of temperature differences in the materials used to construct structures and fill walls. For a specialist assessing the condition of facade plaster, not only the type of cracks is important, but also their width (measured with a calibrated magnifying glass) and depth (to measure it, you need a sample of plaster cut from a scratch). age of scratches also matters – this is determined by the degree of contamination of its edges. After studying the scratches, determining their type and size, the best method for removing them is selected.

Following the crack’s wedge expansion, dust it off, prime it with a strengthening impregnation, and then fill it with an elastic solution. This technique gets rid of some construction and diagonal scratches;

A 20 cm wide strip, 10 cm on each side of the scratch, is cut out of the old plaster. After attaching a metal mesh and a felt relief mat to the base, two layers of plaster solution are applied. This technique is applied when creating growing scratches;

If you have horizontal or vertical scratches, you can fill them with elastic sealing putty after widening them to about 8 mm across the plaster’s thickness and priming with a reinforcing agent; foam can then be pressed into the gap.

Additionally appropriate for filling any cracks brought on by plaster flaws are elastic dispersion paints. They can be applied with or without fiberglass mesh in two or three layers. But gypsum with a high lime content shouldn’t be treated with these organic systems;

Heat-insulating plaster, which consists of an outer waterproof layer and an insulating layer, can also be used to cover scratches in walls. As a result, we will improve the building’s thermal comfort in addition to updating the facade. Furthermore, scratched surfaces can be successfully restored using the conventional insulation system, which was renamed ETICS (lightweight wet method, later BSO) and involves applying a thin layer of plaster to mineral wool or polystyrene;

• use of liquid paint systems;

In order to restore a smooth, even surface, old plaster repair entails carefully evaluating the damaged areas, removing loose or crumbling material, and applying fresh plaster. This procedure preserves the structural integrity of your house and helps to stop additional damage in addition to making your walls look better for longer.

They fill and seal cracks rather than sealing them shut. The main uses for them are to get rid of shrinkage, baggy, and mesh scratches.

Video on the topic

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