Each week we’re bringing you an in-depth look at one of the standard conditions we encounter and document during inspections of buildings and civil structures.
Part 5: Surface Loss
Surface loss describes the disappearance of material at the outer faces of masonry units or concrete, and includes erosion, delamination, exfoliation, chipping, glaze loss and face spalling. Surface loss can lead to the material becoming friable. Exfoliation may also be referred to as blistering.
Erosion of concrete and masonry materials can occur due to scouring by wind and water, or abrasion by other materials. Delamination applies only to natural stone, and results from the separation of layers along bedding planes.
Exfoliation is the loss of the outer surface of a material in thin layers. Water infiltration is a major cause of delamination and exfoliation.
Chipping refers to shallow surface loss, typically at the edge of a masonry unit. Glaze loss applies only to terra cotta, resulting from water infiltration or poor glaze-body “fit”. Face spalling generally applies only to brick, and can result from thermal expansion forces resisted by inappropriately-hard mortars.
A material is described as friable when a loss of cohesion within the unit or concrete, caused by water infiltration, has rendered it powdery or crumbly. Inappropriate surface treatments or cleaning techniques can contribute to several types of surface loss.
Next in this series: Failed Joints in Masonry