Which masonry bond is considered the weakest?

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

Answer: (A)

The strength of a masonry wall comes from how bricks are tied together across courses. When bricks are stacked directly on top of each other with all vertical joints aligned, as in a stack bond, there is little resistance to sliding or cracking along those joints. The wall relies mainly on the mortar to carry loads, and there’s no interlocking between courses. This makes stack bond the weakest among common bonds, especially for load-bearing walls or under lateral forces. Other bonds interrupt the vertical joints to create interlock: running bond staggers joints so no continuous vertical joint runs the full height; English bond alternates courses of headers and stretchers for strong interlock; Flemish bond blends headers and stretchers within each course for good shear resistance. So stack bond is considered the weakest.