Issue 38 – May 2012
The Department of Building and Housing has published technical guidance for repairing and rebuilding foundations in Technical Category 3 (TC3) areas of Canterbury.
Appendix C – Interim guidance for repairing and rebuilding foundations in Technical Category 3 provides information and criteria to help engineers, building control officials, and insurance assessors to determine if foundations can be repaired or need to be replaced, and provides options for repair and replacement. The guidance is an appendix to DBH's November 2011 Revised guidance on repairing and rebuilding houses affected by the Canterbury earthquake sequence.
For properties where new or replacement foundations are required, three foundation types are outlined. These are: deep piles, site ground improvements, and surface structures with shallow foundations.
Each of these foundation types have different capabilities to accommodate various levels of vertical settlement and lateral spreading, and place different constraints on the type of dwelling that the foundation can support.
Chartered Professional Geotechnical Engineers will be able to determine what foundation type is appropriate for each property based on information obtained from site-specific geotechnical assessments.
It is anticipated that this guidance will be updated over time to reflect new innovations, knowledge, and practical experience.
Summarised from information supplied by DBH.