Causes of External and Internal Plaster Cracks: A Comprehensive Guide
Cracks in external and internal plaster are common issues in buildings, often caused by structural errors, thermal expansion, or poor construction practices. This article explores the main reasons behind these cracks and how to prevent them. We’ll discuss cracks that occur where beams meet walls, vertical cracks at column-wall junctions, and the importance of following proper construction guidelines. Practical solutions will also be provided to help avoid these problems in future projects.
1. Cracks at Beam-Wall Junctions
One of the most frequent types of cracks occurs where concrete beams meet brick walls. These cracks usually appear due to improper filling of gaps between the beam and the top of the wall during construction.
- Causes:
- Leaving a gap between the beam and the wall without proper filling.
- Differences in thermal expansion coefficients between concrete and brick materials.
- Rapid drying and shrinkage of mortar used to fill small gaps.
- Solutions:
- Cut small pieces of bricks to fully fill the gaps.
- Install a fiberglass mesh (20 cm wide) to bridge the area between the beam and the wall.
- Use triangular wooden supports to reinforce the space between the beam and the wall.
2. Vertical Cracks at Column-Wall Junctions
Vertical cracks often form where concrete columns meet brick walls. While these cracks are not structurally dangerous, they indicate underlying construction flaws.
- Causes:
- Lack of connection between the columns and walls.
- Thermal expansion differences between concrete and brick materials.
- Solutions:
- Install metal connectors between the columns and walls every 40 to 50 cm.
- Use fiberglass mesh (20 cm wide) to reduce the effects of expansion and contraction.
3. Key Construction Guidelines to Prevent Cracks
To minimize the risk of cracks, it is essential to follow specific construction practices. These guidelines ensure structural stability and reduce stress on walls.
- Allow Concrete Sufficient Time to Cure:
Concrete should be given at least 28 days to reach its full strength before proceeding with other construction activities. - Avoid Building Walls Before Completing the Structural Frame:
Walls should only be constructed after the structural frame, including beams and columns, is fully completed. This minimizes pressure on the walls and reduces crack formation. - Allow the Structure to Settle Before Finishing Work:
After completing the structural frame, it is advisable to wait three months before starting finishing works like plastering. This allows the building to stabilize.
| Construction Phase | Recommended Timeframe |
|---|---|
| Pouring Concrete | 28 days |
| Building Walls | After structural completion |
| Starting Finishing Works | After 3 months |
4. The Role of Painting and Final Treatments in Reducing Cracks
After completing interior finishes, apply paint and sealants to minimize the appearance of cracks. For example, use gypsum putty or textured coatings to fill minor cracks. However, ensure the structure is stable before taking these steps.
Frequently Asked Questions (FAQ)
1. What are the main causes of plaster cracks?
Plaster cracks often result from thermal expansion differences between materials or construction mistakes like leaving gaps between beams and walls.
2. Are plaster cracks dangerous?
Most cracks are not dangerous but may indicate structural issues if left unaddressed.
3. How can cracks be avoided during construction?
To avoid cracks, ensure gaps are properly filled, allow sufficient curing time for concrete, and let the structure settle before finishing work.
4. Can existing cracks be repaired?
Yes, cracks can be repaired using gypsum putty or sealant paint, but the root cause must first be addressed.
Summary Table of Key Points
| Topic | Details |
|---|---|
| Cracks at beam-wall junctions | Caused by thermal expansion differences and unfilled gaps between beams and walls. |
| Vertical cracks at columns | Result from a lack of connection between columns and walls and material differences. |
| Construction guidelines | Allow concrete to cure for 28 days, wait for structural stability, and fill gaps properly. |
| Role of painting and treatments | Use gypsum putty or sealant paint to reduce crack visibility after structural stability is ensured. |
Conclusion
Addressing plaster cracks requires a thorough understanding of their root causes. Whether the cracks result from construction errors or natural factors like thermal expansion, practical solutions always begin with identifying and resolving the underlying issue. By following proper construction practices and applying effective techniques, the likelihood of these problems can be significantly reduced. With careful planning and execution, builders can ensure durable and crack-free plaster finishes.
