Chapter 7: Evaluation and Identification of Building Cracks

Customers frequently ask a variety of questions during my home inspection. This article addresses some common concerns shared by many: crack origin and identification.

Cracks are very common in buildings, often on interior or exterior walls, ceilings and cement floors. Cracks are categorized into the following:

  1. Shrinkage cracks caused by water evaporation and loss in construction materials. These cracks often appear on the surface of interior walls, or joints of interior walls. (Shrinkage Cracks)
  2. Structural cracks caused by uneven settlement of foundation. (Structural Cracks)
  3. Heaving cracks caused by instability of the foundation soil, partial heaves or twists. (Structural Cracks)
  4. Cracks caused by lateral force. (Structural Cracks)

Building itself is not static. With constantly changing external conditions, such as ambient temperature, unusual snowfall, rainfall, artificial changes of dead load in the original design and live load changes based on people’s different lifestyles, foundation will change, resulting in damages in the structure. Some changes are benign and some may pose serious safety hazards. Cracks are symptoms of building structure change. An experienced home inspector will determine the condition and stability of the foundation and structure based upon the shape, size and location of the cracks, then provide opinions and recommendations to the customer.

Given the complexity of crack origin, crack evaluation and identification of all categories will be individually addressed in future series. This column will describe cracks caused by uneven settlement of foundation.

The prominent difference between shrinkage cracks and structural cracks is that shrinkage cracks are more random with no typical characteristics. On the contrary, structural cracks will have characteristics in shape, location and size. Additionally, inter-related cracks must exist somewhere else. For example, cracks on exterior wall must have cracks on interior walls correspondingly, or reflect in other locations.

Most structural cracks are in vertical shape, or 45 degree diagonally originated from the corner of an opening. Openings are the weakest spots in a building. In general, any uneven settlement of foundation will exhibit cracks in the vicinity of openings. The foundation and structure may have more serious problem when cracks wider than 1/8″ are observed on exterior walls.

When multiple parallel diagonal cracks are observed on exterior walls, even if the size is less than 1/16″, it could still indicate foundation deficiency. Some cracks in the shape of pyramid originated from a corner of exterior walls also indicate uneven foundation settlement.

Uneven foundation settlement will not only affect the structure of a building, also cause potential hazards to electrical systems, gas supply systems and plumbing systems. It is a vital task of a home inspector to correctly evaluate cracks and draw a relatively reliable conclusion on the performance of building foundation and structure.

Recent News:

US Consumer Product Safety Commission recently recalled the following merchandise:

Genie Recalls Garage Door Openers Due to Fire Hazard.

Consumers should immediately stop using and unplug the recalled garage car opener and contact Genie to receive a free repair kit, which includes a new control board and installation instructions.

Genie serial number: 11214, 11215, 11235, 11256, 11298, 11311, 11312, 11313, 11326, 11327, 11336, 11332, 11347, 11348, 12006, 12009, 12018, 12019, 12026, 12027, 12034, 12036, 12037, 12038, 12058, 11214, 11313, 11332, 11336, 11347, 11348, 11349.

By Michael Zhang

Published in the April edition of Texas Capital News, 2014