What is the maximum allowable crack in an expansion joint?

• A. 1/4 inch
• B. 1/16 inch
• C. 3/8 inch
• D. 1/2 inch

Answer: (C)

Expansion joints are built to absorb movement from temperature changes and soil shifts, so the width of a crack in the joint indicates how much movement can still be accommodated while keeping a seal. The largest crack width that keeps the joint functioning properly is three-eighths of an inch. This size allows the filler or sealant to flex without pulling away, helping prevent water intrusion, weed and root intrusion, and damage from freeze-thaw cycles. Cracks larger than this, like a half inch, signal the joint isn’t performing and needs repair or replacement. Very small gaps, such as a sixteenth or quarter inch, don’t leave enough room for normal seasonal movement and can lead to binding or future cracking.