1. Why Cracks Are More Common in Autumn and Winter
As humidity decreases, the evaporation of moisture from walls causes volume contraction, leading to fine cracks. These cracks are usually as thin as a hair strand, evenly distributed and uniform in color, which is a phenomenon of plaster layer dry shrinkage and does not affect structural safety. Additionally, the building's concrete and metal components expand and contract with temperature changes. If different materials have inconsistent expansion and contraction rates, gaps can easily form at joints, commonly seen around windows, door frames, and beam bottoms. However, if cracks are accompanied by wall blistering, darkening, or signs of water seepage, the problem is not just dry shrinkage; it may be related to external wall leakage or pipe leaks. Prolonged moisture can cause the plaster layer to loosen or even spall, requiring prompt attention.
Two: How to Identify the Nature of Cracks
The most common dry shrinkage cracks usually only affect the surface; clean them and then fill with repair paste and repaint; seam cracks that appear near doors or windows are often caused by thermal expansion and contraction, and should be repaired with flexible sealant to allow the wall to expand and contract slightly; if the crack is darker in color and accompanied by water stains or peeling, it is a water seepage crack, and the water source must be identified before repair; when the crack width exceeds three millimeters, runs diagonally through the wall, or is located in structural positions such as columns, beams, or floor slabs, it may be a structural crack, which should not be repaired on your own and requires immediate inspection by a professional engineer.
Three, Home Self-Inspection Three-Step Method
Step One, observe the location and direction of the crack. Cracks in the center of the wall are mostly due to surface drying shrinkage; those near windows or bathroom exterior walls require attention to rainwater or pipe seepage; if cracks span multiple walls or extend to the ceiling, be highly alert.Step Two, record the length and changes of the crack. Lightly mark both ends of the crack and write the date; if the crack significantly widens within a few weeks, it indicates the problem is still developing.Step Three, maintain stable humidity and temperature differences. Excessive dehumidification can cause the plaster layer to become too dry and contract; it is recommended to keep indoor relative humidity between 45% and 60%; when using heating, avoid excessive temperature differences to reduce repeated expansion and contraction of the wall.
4. Repair and Prevention Recommendations
For minor cracks, first remove dust with a soft brush, then apply repair paste or flexible paint after drying; if the wall needs repainting, it's advisable to choose latex paint with moisture and mildew resistance. For seam cracks, repair with acrylic or silicone caulk, avoiding overly hard materials that could cause re-cracking. If water seepage is suspected, check window sills, exterior wall tiles, and bathroom corners for gaps or seepage marks; if wall-internal pipe leakage is suspected, have it inspected by a registered plumber or engineer—do not rely solely on plastering to conceal, as this may delay resolution.
Wall Repair First Choice: Wall Repair Paste
- Form: Paste/mud-like wall repair material.
- Advantages:
- Relatively affordable price.
- Easy to use, suitable for DIY beginners.
- Considerations/Disadvantages:
- Effectiveness or durability may not be as long-lasting as professional large-scale plastering materials (such as base coat plaster).
- If the wall substrate or water leakage/structural issues are not resolved, relying solely on repair material may only address the symptoms, not the root cause.
- Suitable for shallow cracks or holes, not recommended for large areas of water leakage/structural cracks.
5. When to Seek Professional Assistance
If the crack width exceeds three millimeters, is accompanied by wall deformation or signs of water seepage and odor, or appears on load-bearing walls, beams, or columns, you should promptly contact qualified professionals or the Buildings Department for assessment. Early intervention can prevent further structural damage and avoid larger repair costs in the future. During the transition from autumn to winter, as the home environment shifts from humid to dry, minor cracks on walls are not uncommon. As long as they are confirmed to be surface-level issues, repairs can be postponed until the climate stabilizes. However, if cracks continue to widen or are accompanied by water seepage, it is essential to identify the source as soon as possible. Maintaining balanced indoor humidity and regularly inspecting wall conditions are the best maintenance practices to slow down wall aging and prevent water seepage, ensuring your home remains sturdy and fresh even in the dry season.