What is the maximum spacing of control joints in driveways?

What is the maximum spacing of control joints in driveways?

• A. 30 feet
• B. 20 feet
• C. 10 feet
• D. 15 feet

Answer: (B)

Control joints are placed in a concrete driveway to guide where cracks will form as the concrete shrinks and expands with temperature changes. By scheduling joints at appropriate intervals, you keep cracking along the joints rather than randomly across the slab, which preserves appearance and durability. For driveways, the commonly accepted maximum spacing is about 20 feet. If joints are spaced farther apart, a crack is more likely to form in the middle of the slab, which is undesirable. Choosing a tighter spacing, like 10 or 15 feet, adds more joints and cost without providing additional practical benefit. So 20 feet balances effective crack control with practical installation. Joint depth is typically about one-quarter the slab thickness to be effective.

Control joints are placed in a concrete driveway to guide where cracks will form as the concrete shrinks and expands with temperature changes. By scheduling joints at appropriate intervals, you keep cracking along the joints rather than randomly across the slab, which preserves appearance and durability. For driveways, the commonly accepted maximum spacing is about 20 feet. If joints are spaced farther apart, a crack is more likely to form in the middle of the slab, which is undesirable. Choosing a tighter spacing, like 10 or 15 feet, adds more joints and cost without providing additional practical benefit. So 20 feet balances effective crack control with practical installation. Joint depth is typically about one-quarter the slab thickness to be effective.