What Is an Expansion Joint?

An expansion joint (dilation joint) is a deliberately created gap between two adjacent structures. The separated elements or their fragments independently bear anticipated loads, deformations, and displacements caused by various factors, such as:

• Temperature changes,
• Uneven building settlement,
• Shrinkage or expansion of building materials.

Types of Expansion Joints

Expansion joints are categorized into:

• Structural Expansion Joints – Separate sections of a building, forming an independent static system. Used in cases of changes in foundation type, construction layout, large load differences, and extensive horizontal building dimensions.
• Thermal Expansion Joints – Designed to eliminate the impact of large stresses that could cause thermal deformations due to material expansion, such as in railway or tram tracks.
• Technological Expansion Joints – Counteract shrinkage or expansion of materials used in construction elements.
• Anti-Vibration Expansion Joints – Reduce or eliminate vibration effects and shocks between structural elements. Used between machines and their foundations, in flooring under vibrating machinery (e.g., hammers), and in areas prone to earthquakes or mining damage.

The best product for floor expansion joints is Bostik P795 SEAL’N’FLEX PREMIUM.

When Is an Expansion Joint Used in a Building?

An expansion joint is a versatile solution widely applied in construction and interior finishing. Different types of joints correspond to specific applications.

In single-family housing, expansion joints:

Increase durability and prevent structural damage,
Prevent cracking and surface defects,
Are crucial in large buildings, homes with long walls, and row houses or semi-detached buildings.

One of the most common applications is floor screed expansion joints, which are essential for preventing cracks. If a screed crack is left unprotected, it can later cause damage to the finished flooring.