If there is a common problem in a house, it is the appearance of cracks on the walls or facade. To correctly repair a crack, it is necessary to determine its type: inert crack or moving crack?
Moving cracks on walls and facades
Moving cracks: definition
Also called live or active cracksthese crevices in the wall or façade evolve over time. They change as they get bigger when the house moves. It is important to follow their evolution so that they can be repaired correctly and determine their level of danger.
Cracks can appear for several reasons: freezing and thawing, drought or overflow of rain, ground movements or a lack of performance. Although common, it is necessary to watch them.
The risks associated with moving cracks
There are 3 levels of danger of cracks: microcracks, fine cracks and dangerous cracks. In general, microcracks are too small (less than 0.2 mm) to have a negative impact on the structure of the house. Fine cracks (0.2 to 2 mm wide) are only potentially dangerous if they are moving or multiplying. Finally, dangerous cracks or cracks have a width greater than 2 mm and can be through, ie they pass through the wall.
How to seal a moving crack?
Since cracks are constantly changing, you have to use a flexible coating, who will follow the movements of the house, without cracking himself.
1. Clean the crack
First, you have to clean the crack. With a hard brush, remove all that moves: lichen and moss, dust and rubble. This will facilitate the adhesion of the plaster in the crack. It is also possible to apply a treatment against mosses and lichens before resealing the crack.
2. Enlarge the crack
You have to start by widening the crack. Use a triangular scraper (mason's scraper or special cracks) or a knife for filling to form a gutter. This facilitates the application of the coating in step 3. The gutter must be neat. Clean a second time.
3. Clog the crack with a suitable coating
Fill the crack with the plaster: be generous on the dose and check that the plaster occupies the full depth of the crack. There are different colors of coating, which allows you to choose a shade closest to that of your facade.
4. Treat the finishes
Use a smoother and sponge any traces of plaster around the crack and wait for the plaster to dry.
In any case: do not take any risk, a crack can very quickly become dangerous. Seek a building professional for advice and assistance.