Ask an Expert: Drought & Settlement

Ask An Expert is a question-and-answer column designed to address common questions related to forensic investigation and property damage. Each month we’ll feature one or two questions submitted by you – our readers and customers – and provide detailed, easy-to-understand answers. Email your questions to [email protected] or submit your questions here.

Question #1: Can you differentiate between consolidation from vibration and from drought compaction?

Rich Grimshaw, P.E.: Yes.  Consolidation from vibration is more prevalent in sands and loams than it is in clays.  Additionally, consolidation from vibration can occur without any change in soil moisture content.

Compare this to drought compaction which requires: 1) the presence of clay soils (not sand or loam) that are prone to significant volume change with moisture content, and 2) a significant change in moisture content; that is, going from wet or moist to very, very dry (desiccated) clay soils.

Question #2: What is the repair for settlement cracks?

Rich Grimshaw, P.E.: Many repair techniques are available, and choosing the best one will depend on the unique conditions of each location.  First, the root cause of the settlement should be remedied before repairing any cracks.  Once that is done, cracks can be repaired.

Cracks in interior and exterior concrete slabs can be filled with epoxy.  Cracks in mortar joints in brick and block walls can be ground out and repointed.  Cracked bricks have to be individually removed and replaced.   Small cracks in gypsum board (a.k.a. drywall or sheetrock) can be taped and patched, but larger cracks are better repaired by removing and replacing the gypsum board around the cracked area.

Learn more by attending an upcoming webinar or viewing other resources at


About the Expert

Richard Grimshaw joined Donan in 2009 and currently serves as a forensic engineer and training manager based out of the firm’s Atlanta, Georgia office. Mr. Grimshaw has worked in the following industries: residential and light commercial construction, and steel and concrete structure design for institutions, power plants, warehouses and manufacturing facilities. His areas of expertise are residential construction/quality standards, mold origin and cause, wood decks, and water intrusion. Mr. Grimshaw’s other project capabilities include roof inspections and structural impact losses, among others.

Mr. Grimshaw is a licensed professional engineer in Alabama, Georgia, South Carolina and Tennessee, and a licensed residential/ general contractor in Georgia. He holds a Bachelor’s degree in Civil Engineering from the Georgia Institute of Technology, and a Master of Business Administration from Georgia State University.

View Rich’s full professional profile here.

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