Differential Settlement of a Single-Story House

Project Overview

The subject property is a 20 year old single story residence with a basement. Cracking was first observed on interior partition walls and has since progressed to portions of the exterior walls. The two car garage slab exhibited localized depressions accompanied by areas of concrete spalling. Water staining was also noted along the basement foundation walls, suggesting potential moisture related concerns.

Scope of Services

Geotechnical Engineering

• Performed a comprehensive subsurface investigation to evaluate underlying soil conditions contributing to settlement distress.
• Advanced five soil borings at critical locations to depths of approximately 10 to 15 feet using a drilling rig.
• Collected representative soil samples for laboratory classification and index property testing.
• Conducted Standard Penetration Testing (SPT) to assess in‑situ soil strength and bearing capacity beneath existing footings.
• Completed plasticity testing, confirming the presence of highly plastic marine clays underlying the foundation.
• Determined that differential settlement resulted from uneven swelling of the marine clay soils caused by localized moisture variations.

Structural Engineering

• Evaluated the impact of soil‑related movement on the existing foundation system and associated structural components.
• Assessed the adequacy of existing footing depths relative to the active moisture zone within the underlying clay soils.
• Developed structural remediation recommendations, including underpinning the rear foundation wall by extending footings approximately five feet deeper to reach more stable bearing strata.
• Recommended improvements to site drainage to minimize water accumulation near foundation walls and reduce future moisture‑induced soil movement.