Understanding the reported concern
NGS was asked to evaluate an existing two-story residence for evidence of potential soil movement. The initial visit considered visible distress, drainage conditions, evidence of erosion and the building’s relationship to the surrounding ground.
The observations included exterior and interior cracking, drainage features needing maintenance and areas where runoff could collect near the building. NGS documented those conditions and recommended a floor-level survey to provide additional information.
Adding measurements to the observations
NGS performed the subsequent floor-level survey using a manometer, or water level, to measure relative elevations on the first and second floors. The measurements documented differences across the building, including a localized difference near an addition.
The survey report used those measurements with the earlier observations to develop recommendations. At that time, NGS did not consider foundation releveling or underpinning warranted and recommended structural evaluation of the second-story elevation difference.
Updating the assessment with new evidence
Later photographs showed that an area initially perceived as a foundation crack was a crack in the stucco. NGS issued a follow-up report documenting that no foundation crack was visible in that area after the stucco was removed and that the stucco had been repaired.
The follow-up illustrates why an investigation must distinguish a visible finish defect from damage to the underlying foundation. The later evidence changed the interpretation of that specific observation.
A focused scope and a clear record
The assignment consisted of engineering observations, relative floor-elevation measurements and review of subsequent information. It provided a record of the conditions evaluated and recommendations appropriate to those findings.
NGS’s current forensic engineering services also use floor-elevation measurements to help document patterns of unevenness. The appropriate scope depends on the reported concern, available records and whether further subsurface investigation is needed.
Engineering services by Noorzay Geotechnical Services, Inc. Meet Maihan Noorzay, M.S., P.E., G.E.