How to deal with the cracking of the external wall of commercial housing? In our life, some owners will find cracks in the wall when they buy new houses for decoration. Cracks in the wall are generally caused by improper construction by developers. The following details how to deal with the cracking of the external wall of commercial housing.
How to deal with cracks in the external wall of commercial housing? 1 how to deal with cracks in external walls?
First, the primary reason is that grass-roots treatment is not in place. Solution:
1, the obvious concave and convex parts on the concrete surface should be leveled in advance or filled with 1: 3 polymer cement mortar.
2. Before painting or chemical roughening, the dirt on the wall surface should be removed, and the surface should be watered and wetted in advance (the inner wet surface is dry).
3. The concrete base should be treated by manual or chemical roughening; Measures such as chemical roughening or full laying of meshes should be taken to strengthen the bonding force of lightweight block base.
4, the outer wall foot hand hole and the hole should be layered compaction, and brush a waterproof enhancement layer on the outside of the hole.
5, different materials matrix junction, must be laid anti-crack net or glass fiber net, and the lap width between the matrix should not be less than150 mm. ..
Second, the external wall plastering may not notice. Solution:
1, the surface coating should be mixed with polypropylene anti-crack fiber.
2, plaster surface must be set frame joints.
3. It has no influence on the structural safety, but it is hard to say that the wall is watertight, and it will definitely leak.
4, solutions, such as rain or external wall water spray, find out the leakage point, to repair. The exterior wall has been redecorated.
5. I don't know if the external wall is insulated. If it's insulated, it's more complicated, and there's no leakage position at all.
What are the causes of cracks in the external wall?
There are many reasons for the leakage of the external wall of residential projects, such as design mistakes, improper material selection, irregular construction technology, careless details, improper decoration after delivery, and the influence of natural environmental conditions. Specifically, there are the following aspects:
1) Design and maintenance of external wall downpipe;
2) The reserved hole in the external wall is poorly sealed;
3) The production and installation of aluminum alloy or plastic steel windows are not standardized;
4) The external wall brick base is not thoroughly cleaned, the paste mortar is not full, and there is water or accumulated water between the wall and the brick;
5) Exterior wall plastering cracks;
6) uneven settlement of foundation leads to wall cracking;
7) In the second decoration stage of the house, the wall cracks due to structural changes caused by disorderly construction;
8) Temperature cracks on the external wall of the top surface of the building.
First, the causes of cement mortar cracks
1, improper selection of raw materials and ingredients.
(1) Some construction units chose better cement and aggregate for the beams and columns of buildings during construction, but mistook low-grade cement and fine aggregate for painting, without considering the structural safety, resulting in large shrinkage and cracking of cement mortar.
(2) Simply adding gypsum or lime powder to the ingredients of cement mortar will improve the workability, but the mortar strength will decrease, the shear strength and bond strength will also decrease, and it is easy to shell (empty drum) and crack.
2, improper construction technology or not according to the specification requirements.
(1) The distribution of frame bars in mortar plastering is unreasonable or embedded too deeply, which destroys the integrity of the bottom of the external wall.
(2) The jointing mortar on the wall is not strong enough, the thickness is not enough, the density is uneven, and the mortar is mixed unevenly or manually.
(3) Improper construction technology of mortar external painting, insufficient or excessive watering by maintenance personnel (too wet or too dry at the grass-roots level) will cause the surface to fall off or dry.
④ The materials and properties of different wall materials, such as red brick, hollow clay brick, cement hollow block and aerated concrete block, have not been mastered, so different operation methods should be adopted for painting.
(5) In the process of wall masonry, the mortar strength is poor, the cohesive force is not enough, it is not dense enough, the masonry integrity is poor or the masonry method is wrong, resulting in cracks, empty joints and blind joints.
⑥ Operators usually hold a brick in their left hand and put cement mortar on the brick in their right hand at work, which will easily lead to the absence of cement mortar in the part where the brick is held in their left hand, and the empty drum will cause leakage when pasting.
3. Cracks caused by structural deformation of the wall: uneven settlement of the foundation, excessive spacing between transverse walls, insufficient reinforcement at the corner stress concentration of brick walls, too large openings in doors and windows, improper setting of deformation joints and other reasons lead to structural deformation cracks in the wall due to insufficient strength, rigidity and stability, which leads to cracks in the mortar layer.
How to deal with the cracking of the external wall of commercial housing II. What if the wall of the house is cracked?
1. If the cracks are caused by excessive temperature difference, the insulation layer is basically not finished. At this time, we need to add insulation layer outside the wall, which can control the temperature rise of the wall and prevent cracks from appearing on the wall.
2. If the cracks are caused by unqualified construction or building materials, pressure grouting should be used to repair the cracks, and putty powder should be applied after it is dry. If the foundation is unstable and the cracks are caused by its falling, we can also use cement to fill the cracks at this time. Wait until it is dry before applying putty powder. Finally, check the repair situation.
Second, why does the wall crack?
1. If the joint is cracked, it may be influenced by the surrounding environment or caused by external forces. It may be that the surrounding decoration house, people hit the wall too hard, resulting in a little crack in the joint. It is also possible that gypsum boards or floors have shortened changes. Generally speaking, the cracks at the joints are usually vertical or horizontal. It is possible that the foundation settlement is unstable, or the temperature difference is too large to cause cracks.
2. It may be that the temperature difference is too large, which causes thermal expansion and cold contraction, or that the construction or building materials are unqualified, or that the foundation is unstable.
3, it is also possible that the cement ratio is not appropriate, and the brush is too thick when brushing the ash layer and putty layer, which leads to unreasonable wall joints and small cracks. Or unqualified decoration materials are used during construction, which will lead to cracks after construction.
How to deal with cracks in the external wall of commercial housing? Cracks appear on three sides. Including two cases, one is that the original wall itself has cracks, and no appropriate treatment measures have been taken in the later decoration process; Secondly, the original wall did not crack at the time of decoration, and cracks appeared in the later stage due to uneven settlement of foundation and great temperature change.
Treatment: this kind of crack can't be repaired by ordinary decoration methods, so we must find professional building structural personnel to take corresponding measures according to the actual situation.
2. Cracking at the joint
Cracking at the root of the wall joint will lead to cracking on the wall surface. Cracks at joints mainly occur at the joints between reinforced concrete shear wall and ceramsite brick, reinforced concrete beam and ceramsite brick, back-blocked door opening, gypsum board partition wall and original wall. Cracking at joints is mainly due to the shrinkage and position change of gypsum board, precast partition board and precast floor due to the influence of surrounding environment or external force, which leads to cracks at joints, generally vertical or horizontal.
Treatment: It is suggested to repair the whole building after the deformation tends to be stable, and the repair in a short time is prone to be repeated.
3, putty layer cracking
Scraping putty on the wall can make the wall more smooth and delicate, and the flatness is much higher than that of cement wall, which makes the wall paint better and saves paint. If the putty layer cracks, it is easy to cause the surface layer to crack. Therefore, attention should be paid to avoid cracks in the putty layer during construction.
Treatment method: If the cracks have penetrated into the putty layer, first use sharp tools to enlarge the cracks to the size of a screwdriver, fill in the caulking gypsum, grind it flat, paste grid cloth or kraft paper, then level it with putty, and finally paint or paste wallpaper according to the normal process.
4, plaster layer cracking
Cracks in wall plastering layer can be divided into normal cracks and abnormal cracks. Normal cracking mainly refers to cracks in plastering layer caused by shrinkage of cement mortar. Abnormal cracking is mainly caused by improper materials or construction technology. Normal cracking is hard to avoid, but abnormal cracking can be avoided.
Treatment: If there is a large area of hollowing in the plastering layer, the original plastering layer should be knocked off, and the cement mortar plastering layer should be made again. After leveling, it should be painted according to the normal process. However, the cost will be relatively high after this treatment. If there is only a small area of cracking, there is no sand turning, hollowing and falling off, you can stick dacron cloth all over the wall and then paint it according to the normal process.
Does the crack in the wall of the house matter?
It depends on the cracking situation. If there is a big crack in the wall, the impact is still great, and there are many security risks. The owner needs to find someone to find the reason and repair it. However, if there is only a slight crack in the wall, the impact is not great, which may be caused by improper decoration and construction. Just scrape the putty again or pour latex paint into the crack to repair it.