Cracking from Lintel Lift on a Single-Family Dwelling
The above photograph shows a pronounced stairstep crack emanating from the upper corner of a window in a brick wall on the gable end of a single-family dwelling. By pronounced I mean obvious, easily seen.
In the subject case, a closer look at the cracking showed that the edges of the cracking are worn and the fracture surfaces are discolored (Figure xx). The worn edges and discoloration on the cracking indicate that the cracking has been present for some time.
A closer look into the cracking disclosed steel lintels that exhibit corrosion that is so severe that the thickness of the steel has expanded (Figures xx and xx). The expansion of the steel lintel has lifted the brick resting on top the steel lintel, hence the term “lintel lift.”
Lintel lift is not an uncommon phenomenon in residential structures built with clay brick walls. When unpainted, inadequately painted, or inadequately maintained steel lintels are repeatedly exposed to excessive moisture, they corrode. Although the masonry (brick and mortar) provides some protection to the steel from rainfall and wall runoff, the masonry is not water tight. Repeated exposure to wetness causes the corrosion to progress until the steel is consumed or the lintel is removed from the wall. The subject dwelling in our photos was 50 to 60 years old when this photo was taken.
One of the last stages of steel corrosion is the expanding of the steel material. It is similar to the expansion of ice during frost heave in the winter. It is unstoppable and it will lift just about anything above it.
In the subject case, the brick above the lintel has been lifted off the wall. Repointing the crack is not an adequate repair. Repair usually requires temporary shoring of the brick, removal and replacement of the lintel with a hot-dip galvanized or stainless steel lintel, lowering of the brick onto the lintel, replacement of fractured brick units, and routing and repointing of the mortar.
One phenomenon that often accompanies expansion from lintel lift is the outward buckling of the brick wall. Because of this and other conditions that could develop a qualified mason (or in some situations a structural engineer) should examine and evaluate the condition of the ties that hold the brick back to the backup wall, having them replaced as required, and should evaluate the condition of the masonry, recommending additional repair, repointing, or replacement as necessary.