The Ontario Building Code | Subsurface Investigation
4.2.4.2. Subsurface Investigation
(1) A subsurface investigation shall be carried out to the depth and extent to which the building or excavation will significantly change the stress in the soil or rock, or to such a depth and extent as to provide all the necessary information for the design andconstruction of the excavationor the foundations.
In Plain Language
A subsurface investigation must extend to the depth and area over which the proposed building or excavation will significantly change the stress state in the ground, ensuring the investigation actually covers what matters for the design.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.