Isolation joints separate slabs from walls and columns; what is the term used for these joints?

Isolation joints separate slabs from walls and columns; what is the term used for these joints?

• A. Isolation
• B. Expansion
• C. Control
• D. Construction

Answer: (A)

Isolation joints are used where a concrete slab must move independently from adjacent structural elements like walls or columns. They create a gap filled with flexible material so the slab can shrink, settle, or expand without transferring movement or cracks into the wall or column. This exact purpose is what defines the joint as isolation. Expansion joints, by contrast, are for thermal expansion and contraction between elements; control joints are placed within slabs to control where cracks will form; construction joints connect pours.

Isolation joints are used where a concrete slab must move independently from adjacent structural elements like walls or columns. They create a gap filled with flexible material so the slab can shrink, settle, or expand without transferring movement or cracks into the wall or column. This exact purpose is what defines the joint as isolation.

Expansion joints, by contrast, are for thermal expansion and contraction between elements; control joints are placed within slabs to control where cracks will form; construction joints connect pours.