When excavation support becomes a geotechnical issue
Excavation for basements, retaining walls, pools and building platforms can expose soils, fill or rock that require project-specific assessment. The need for temporary or permanent support depends on excavation geometry, ground conditions, adjacent structures and the proposed construction methodology.
An excavation close to a boundary or neighbouring footing should not be assessed solely by depth. Ground variability, groundwater and existing loads can all influence the information needed by the structural or temporary-works designer.
A suitable investigation may consider the subsurface profile, potential founding levels, excavation conditions, groundwater observations and site-specific geotechnical parameters where appropriate to the agreed scope.
Shoring, retaining and structural design should be completed by the appropriately engaged designer. A geotechnical report provides ground-related information and recommendations within its agreed scope; it does not automatically constitute a completed shoring design.
What to provide before excavation starts
Provide proposed excavation and basement drawings, boundary setbacks, available survey, nearby-building details and any existing geotechnical information. If a council, certifier or structural engineer has requested specific assessment, send the original wording.
Early ground assessment can help the project team consider practical constraints before an excavation method or support arrangement is finalised.
Common questions
Excavation and shoring assessment: common questions
Does excavation depth alone determine whether shoring is needed?+
No. Support requirements depend on the actual ground conditions, excavation geometry, water, nearby structures, construction methodology and relevant design or regulatory requirements.
Is a geotechnical report the same as a shoring design?+
No. Geotechnical information can inform design, while shoring or structural design must be undertaken by the appropriate engaged design professional.
Should nearby buildings be considered in an excavation assessment?+
Yes. Neighbouring structures, foundations, boundaries and existing retaining features can be relevant to project-specific excavation and support planning.
Need Discuss your excavation assessment in Sydney?
Get a scope matched to the project
Send the site address, proposed works, current plans and any request from your builder, engineer, council or certifier. Sydney Geotechnical will review the information and confirm an appropriate scope and fee.
This guide provides general information only and is not a substitute for investigation, engineering advice, footing design or approval advice for a particular property. Project requirements and ground conditions must be assessed site by site.
