Lightweight Bricks Crack After Installation? Here's the Cause and Solution

Lightweight bricks are known as a modern building material that is strong, lightweight, and easy to install. However, in practice, it is not uncommon for lightweight brick walls to crack after installation. These cracks can be as thin as hairs or even clearly visible and long.
To avoid further damage, it is important to understand the causes and how to properly address them.

1. Causes of Lightweight Brick Cracks After Installation
a. Inappropriate Mortar
Using an inappropriate mortar—for example, one that is too thin or too thick—can weaken the bond between lightweight bricks. This makes the wall structure unstable and prone to cracking.
It is recommended to use a special mortar for lightweight bricks that has high adhesion and flexibility.

b. Plastering Too Quickly
Many workers apply plaster immediately after installing lightweight bricks, even though the material is not yet completely dry and stable.
As a result, when the bricks shrink due to water loss, the plaster will also crack.

c. Movement of Building Structures
Cracks can also be caused by movement of the foundation or an unstable building structure. Changes in load or vibrations from the ground can cause pressure on walls, resulting in small cracks.

d. Lack of Expansion Joints
In large building construction, expansion joints should be present to withstand pressure from temperature changes and building movement. Without these joints, walls will easily crack when temperatures change drastically.

e. Low-Quality Lightweight Bricks
Low-quality lightweight bricks have large pores and weak compressive strength. When exposed to changes in temperature or pressure, these bricks easily break and crack.

2. Solutions for Cracked Lightweight Brick Walls
a. Use Mortar and Plaster Specifically for Lightweight Bricks
Use instant mortar formulated for lightweight bricks for optimal adhesion and greater resistance to cracks.
Ensure the mixture has the right water content—not too runny or too dry.

b. Allow Lightweight Bricks to Dry Before Sanding or Plastering
After installation, let the lightweight brick walls dry for at least 1–2 days before plastering. This will allow natural shrinkage to complete and the surface to be more stable.

c. Add Wire Mesh or Fiber Mesh to the Plaster
To prevent hairline cracks, use wire mesh or fiber mesh at the joints between walls or around door and window frames.

d. Use SNI-Quality Lightweight Bricks
Make sure you purchase lightweight bricks from a trusted distributor that sells SNI-standard products. Quality lightweight bricks have uniform density, a smooth surface, and are not easily broken.

e. Check the Foundation Condition Regularly
If cracks appear consistently, there may be a problem with the foundation. Consult a structural engineer immediately to ensure there is no soil shifting or excessive load.

3. Tips for Preventing Future Cracks
Use adhesives and plaster recommended by the lightweight brick manufacturer.

Avoid installation during very hot weather or heavy rain.

Ensure each joint between walls is reinforced with additional reinforcement, such as wire mesh.

Use a moisture-resistant protective paint to prevent excessive water absorption.

Conclusion
Cracks in lightweight bricks do not necessarily indicate poor building quality; they are often the result of technical errors during the installation and finishing process. By choosing the right materials, following proper work procedures, and using quality products from trusted suppliers, you can prevent these problems from the start.

To get SNI-certified lightweight bricks and other building materials with guaranteed strength, trust PT Intisumber Bajasakti (ISBS) — a trusted supplier in Indonesia.

📞 Phone: 021-66675999
🌐 Web: intisumberbajasakti.com
✉️ Email: info@intisumberbajasakti.com

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