What Are Bowing Walls?
A bowing wall is distinct from a leaning wall, in that the top and bottom of the wall remain in the same plane while the middle of the wall protrudes from the rest of the structure. Bowing walls can have the same appearance as a bulging wall, but both tend to be a result of different environmental factors.
Bowing walls are often the result of a wall being loaded above their capacity (either because of an original design defect or later being used beyond their design limit), although can also just occur as a result of a poor connection back to the original structure, perhaps because of wall tie failure.
In addition, external environmental factors, such as nearby heavy traffic causing small vibrations in the ground, can cause a wall to be subjected to unexpected lateral loads, causing it to fail.
The effect of a bowing wall can be repeated by holding a flexible ruler upright on a table and gently pressing on the top.