What project managers need to know about geotechnical investigations in the case of housing developments

Johannesburg, South Africa georgef@uj.ac.za Geotechnical investigations for housing developments are critical. Often, these are either not carried out or conducted inadequately, negatively affecting the project across the planning, design, construction, and post- construction phases. In addition, there is an apparent disconnect between geotechnical information and project management activities, which may result in delays, cost overruns, design modifications, and even poor construction (leading to cracking of walls, buckling of door and window frames, other defects, or even failure, resulting in a loss of serviceability). This paper employed a qualitative secondary research methodology to provide an overview of geotechnical investigation requirements for housing developments, in accordance with the relevant South African codes and specifications. In this context, it includes the extent of the field investigation, the appropriate tests to be conducted, the minimum number of tests, and the quality control (acceptance or rejection) of results from commercial laboratories. Thereafter, the types of problem soils in South Africa and their potential negative consequences on housing foundations are discussed. This includes their geographical occurrence, identification and nature. The appropriate methods of analysis are also summarised, leading to the classification of soils according to the National Home Builders Registration Council (NHBRC) Site Classes. Finally, the founding options for the different classifications are presented. Other important information not covered by the guidelines that Project Managers need to be aware of is also highlighted. The information in this paper is intended to give project managers an overview of geotechnical investigation requirements and problem soils, with the aim of improving decision-making throughout the project life cycle, thereby reducing uncertainty, project time overruns, and costs, and increasing housing quality. Residents' Acceptance of Incremental and Modular Housing, Lagos State, Nigeria Olatunde Daniel Babalola1 and Ayodeji Samuel Aremu1* Department of Architecture, Covenant University, Ota, Ogun State, Nigeria ayodeji.a