Which masonry bond is typically backed with rigid steel ties due to its relatively weak bond strength?

• A. Flemish
• B. Running
• C. Common
• D. Stack

Answer: (D)

Bond strength in masonry comes from how well bricks or blocks lock together across joints. The key difference is how each course overlaps the one below it. In stack bond, bricks are laid directly over one another with joints aligned in every course, so there’s almost no horizontal overlap and very little interlock between courses. That makes the overall bond relatively weak in resisting bending and shear. To compensate for this weaker inherent strength, walls laid in this bond are commonly backed with rigid steel ties to connect layers or wythes and keep the structure behaving as a single unit. Other bonds, like Flemish, Running, or Common, achieve greater interlock through staggered joints, giving them stronger natural bond and often not requiring the same reinforcement for basic stability.