This situation should be that there is something wrong with the quality of the wall, and it will be dangerous if it is not treated. Check the previous house design first to see how the house is planned. Take a look at the distribution of steel bars on the wall under the windowsill and see how many there are. If there are steel bars, there is basically no danger. If there is no steel bar, it is very dangerous. The reason for this situation is: 1, clay hollow brick and clay solid brick have been restricted and prohibited, and various blocks are widely used in building construction. The wet expansion and dry shrinkage of cement blocks are quite obvious, and the most prominent thing is that cracks and water seepage generally occur in the external walls using cement blocks. When the cement block shrinks greatly after drying, cracks will occur in the wall. 2. Wall blocks are affected by the physical properties of thermal expansion and cold contraction, which will also cause wall cracking. The change of temperature will cause uneven shrinkage of wall blocks, or the expansion and contraction of wall blocks will be unevenly constrained, and the temperature stress exceeding the strength of wall blocks will cause wall cracks. 3. Uneven settlement of building foundation will also cause wall cracking. All the weight of the building is transferred to the foundation through the foundation. Because of the diffusion principle of stress, the foundation ash will settle unevenly. 4. When the surface temperature drops below 0℃, the upper part of the foundation begins to freeze, and the water in the lower part of the foundation will form ice crystals in the frozen layer due to capillary action, which will continue to rise. Volume expansion will also crack the wall bulge.